巴西专利BR102012003529B1 STEEL PIPE AND METHOD FOR THE SAME PRODUCTION

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专利摘要:
Embodiments of the present disclosure comprise carbon steels and manufacturing methods. In one embodiment, the quenching and quick cooling procedure is performed in which a selected steel composition is shaped and heat treated to give a lightly tempered microstructure having a fine carbide distribution. In another embodiment, a dual austenitization procedure is disclosed in which a selected steel composition is shaped and subjected to heat treatment to refine the microstructure of the steel. In one embodiment, the heat treatment may comprise austentinization and rapid cooling of the formed steel composition a selected number of times (e.g. 2) prior to quenching. in another embodiment, the heat treatment may comprise subjecting the shaped steel composition to austentinization, rapid cooling, and quenching for a selected number of times (e.g., 2). steel products formed from embodiments of the steel composition in this manner (eg, pipe bars and seamless pipes) will have high yield strength, for example at least about 1138 mpa (165 ksi) while maintaining a good hardness.
公开号:BR102012003529B1
申请号:R102012003529-4
申请日:2012-02-16
公开日:2019-05-14
发明作者:Eduardo Altschuler；Tereza Perez；Edgardo Lopez；Constantino Espinosa；Gonzalo Gomez
申请人:Siderca Saic；
IPC主号:

专利说明:

STEEL TUBE AND METHOD FOR THE PRODUCTION OF THE SAME
RELATED ORDER [0001] This order is related to the applicant's copending order entitled ULTRA HIGH TENACITY STEEL HAVING GOOD HARDNESS, serial number 13/031133, filed on February 18, 2011, the entire amount of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
Field of the invention [0002] The present invention generally relates to the production of metals and, in some embodiments, concerns methods of producing metal tubular bars having high toughness while simultaneously having good hardness.
Description of the state of the art [0003] Seamless steel tubes are widely used in a variety of industrial applications. Due to the requirements for greater load-bearing capacity, dynamic stress situations and the need for lighter components, there is an increasing demand for the development of steel tubes that have increased toughness and toughness.
[0004] In the oil industry, drill guns made of steel tubes containing explosive charges are used to deliver explosive charges to selected locations
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2/40 wells. The steel tubes used as conveyors for drilling guns are subjected to very high external collapse loads that are exerted by the hydrostatic pressure of the well. On the other hand, during blasting, steel tubes are also subject to very high dynamic loads.
To solve this problem, efforts have been directed towards the development of steel tubes with high toughness, while at the same time, very good impact hardness is maintained.
[0005] At this moment, the highest grade of steel available on the market has a minimum yield stress of around 155 ksi. As a result, thick-walled tubes are often used in certain formations to withstand the high collapse pressures present. However, the use of thick-walled tubes significantly reduces the working space available for explosive charges, which can limit the range of applications in which the tubes can be used.
[0006] From the above, then, there are an need in best compositions for tubular bars metallic and, in Special, systems and methods for bar production tubular metallic with a combination in properties in
high traction and hardness.
SUMMARY OF THE INVENTION [0007] Embodiments of the invention are directed to steel tubes and methods of manufacturing them. In one embodiment, a quenching and tempering procedure is
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3/40 made in which a steel composition is shaped and heat treated to produce a lightly tempered microstructure having a good carbide distribution. In another embodiment, a double austenitization procedure is disclosed in which a selected steel composition is formed and subjected to heat treatment to refine the steel microstructure. In one embodiment, the heat treatment may include austenitizing and tempering the steel composition formed a number of times (e.g., 2) before tempering. In another embodiment, the heat treatment may include subjecting the formed steel composition to austenitization, tempering and tempering a number of times (for example, 2). Steel products, formed from embodiments of the steel composition in this way (for example, seamless tubular bars and tubes) will have high yield strength, for example, at least approximately 165 ksi, while maintaining good hardness.
[0008] In one embodiment, a steel tube is provided. The steel tube comprises:
fencecarbon; in 0, 20% in Weight The fence in 0, 30% in Weight in fencemanganese; in 0, 30% in Weight The fence in 0, 70% in Weight in fence in 0, 10% in Weight The fence in 0, 30% in Weight in
silicon;
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fence in 0.90% in weight a fence in 1.50% in Weight in chrome;fencemolybdenum; in 0.60% in weight a fence in 1.00% in Weight in fenceniobium and in 0.020% by weight about 0 .40% in Weight in fence in 0.01% in weight a fence in 0.04% in Weight in
aluminum;
where the steel pipe is processed to have a yield stress greater than approximately 165 ksi and where the V-notched Charpy energy is greater than or equal to about 80 J / cm ² in the longitudinal direction and greater than or equal at about 60 J / cm ² in the transverse direction around room temperature.
[0009] In another embodiment, a method for making a steel tube is provided. The method comprises providing a carbon steel composition. The method also comprises forming the steel composition in a tube. The method also comprises heating the shaped steel tube in a first heating operation to a first temperature. The method further comprises quenching the steel tube formed in a first temperature quenching operation at a first rate such that the microstructure of the quenched steel is greater than or equal to approximately 95% of martensite by volume. The method also comprises tempering the shaped steel tube after the quenching operation by heating the shaped steel tube to a second temperature less than about
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5/40 of 550 ° C. The steel tube after tempering has a yield stress greater than about 165 ksi and the Charpy energy with a V-notch is greater than or equal to about 80 J / cm ² in the longitudinal direction and 60J / cm ² in the long cross the temperature close to the environment.
[0010]
In another embodiment, a method of forming a steel tube is provided.
The method comprises providing a steel bar.
The steel bar comprises about 0.20% carbon;
about 0.30% manganese;
about 0.10% silicon;
about 0.90% chromium;
about 0.60% molybdenum;
about 0.020% niobium; and about 0.01 by weight to about by weight to about by weight to about by weight to about by weight to about by weight to about% by weight to about
0.30% by weight of
0.70% by weight of
0.30% by weight of
1.50% by weight of
1.00% by weight of
0.140% by weight of
0.04% by weight of aluminum;
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6/40 [0011] The method also comprises forming the steel bar in a tube in a hot forming operation at a temperature of about 1,200 ° C to 1,300 ° C. The method also comprises heating the shaped steel tube in a heating operation to a first temperature of about 880 ° C to 950 ° C for about 10 to 30 minutes. The method also comprises quenching the shaped steel tube in a quenching operation after the first heating operation at a rate such that the microstructure of the quenched steel is greater than or equal to about 95% of martensite. The method also comprises tempering the shaped steel tube after the second tempering operation by heating the shaped steel tube to a temperature between about 450 ° C to about 550 ° C for between about 5 minutes to about 30 minutes in such a way that the final structure has about 95% of martensite with the rest essentially consisting of bainite. The microstructure, after quenching, can also contain spherical carbides having a dimension less than or equal to about 150 pm. The steel tube after quenching has a yield strength greater than about 165 ksi and where the V-notch Charpy energy is greater than or equal to about 80 J / cm ² in the longitudinal direction and about 60 J / cm ² in the transverse direction at a temperature close to the environment.
BRIEF DESCRIPTION OF THE FIGURES [0012] Figures 1A-1C are embodiments of high hardness steel forming methods; [0013] Figures 2A-2B are micrographs of an embodiment of the steel composition after thermal treatments of austenitization, tempering and tempering; and
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7/40 [0014] Figure 3 is a graph of impact energy of
Charpy (CVN) versus voltage limit of flow for steels conformed from in achievements of gift disclosure. DETAILED DESCRIPTION [0015] Achievements gives gift disclosure provide
steel compositions, tubular bars (for example, tubes) formed using steel compositions, and the respective manufacturing methods. Tubular bars can be used, for example, as conveyors for drilling guns for the oil and gas industry. It can be understood, however, that the tubular bars comprise an example of articles of manufacture that can be conformed to embodiments of the steels of the present disclosure, and should in no way be interpreted to limit the applicability of the disclosed embodiments.
[0016] The term bar, as used in this document, is a broad term and includes its common dictionary meaning and also refers to a generally hollow, elongated member that can be straight or have folds or curves and be shaped into a shape predetermined, and any conformation necessary to protect the shaped tubular bar at its desired location. The bar may be tubular, having a substantially circular outer surface and an inner surface, although other shapes and cross sections are also contemplated. In this document, the term tubular refers to any elongated, hollow shape that does not have to be circular or cylindrical.
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8/40 [0017] The terms approximately, approximately ”and substantially, as used in this document, represent an amount close to that declared that still performs a desired function or achieves a desired result. For example, the terms approximately, about and substantially may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1 % of and within less than 0.01% of the declared quantity.
[0018] The term room temperature, as used in this document, has its usual meaning as known to those skilled in the art and can include temperatures within the range of approximately 16 ° C (60 ° F) to about 32 ° C ( 90 ° F).
[0019] In general, embodiments of the present disclosure include carbon steels and manufacturing methods. In one embodiment, a selected steel composition is shaped and subjected to heat treatment to refine the steel microstructure. In one embodiment, the steel composition can be shaped and subjected to heat treatment including austenitization, quenching and tempering. The microstructure at the end of the quench includes about 95% of martensite by volume. Subsequent tempering can be carried out within the range of about 450 ° C to about 550 ° C. The resulting microstructure after quenching includes a good carbide distribution, where the carbide particles are relatively small in size due to the relatively low tempering temperatures. This microstructure provides relatively high toughness and toughness.
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For example, yield strengths greater than 165 ksi and V-notch Charpy energies of at least 80 J / cm ² in the LC direction and at least about 60 J / cm ² in the CL direction.
[0020] In other embodiments, the heat treatment may include austenitizing and tempering the steel composition conformed a certain number of times (for example, 2) to refine the grain size of the final microstructure. This refinement can improve the strength and hardness of the shaped steel composition. The repetition of austenitization and tempering operations twice can be referred to here as double austenitization. It can be understood, however, that austenitizing and tempering operations can be performed any number of times, without limit, to achieve the desired microstructure and mechanical properties. In another embodiment, heat treatment may include subjecting the formed steel composition to austenitizing, tempering and tempering operations a specified number of times (for example, 2), with the tempering performed after each tempering operation.
[0021] It is anticipated that embodiments of articles formed from steel compositions selected in this way (for example, tubular bars and tubes) will have a high yield strength, at least approximately 165 ksi (about 1,138 MPa), as measured by the ASTM E8 standard maintaining good hardness. For example, the experiments discussed in this document illustrate that steels formed from embodiments of the disclosed composition can still exhibit V-notch Charpy impact energies greater than approximately 80 J / cm ² in the LC direction and about 60 J / cm ² at
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10/40 CL direction, as measured according to the ASTM E23 standard. As discussed in more detail below, these improvements in properties are achieved, at least in part, due to the refinement of the microstructure of shaped steel compositions (for example, grain size, package size and average carbide size) as a result the variation in temperatures of the respective austenitization operations.
[0022] For example, in one embodiment, repeated austenitizing and quenching operations at different temperatures can be used to refine the grain size and package size of the shaped steel tube with the aim of improving the hardness of the steel tube . The grain size of the tube can also be reduced by lowering the austenitization temperature, since grain growth is a controlled diffusion process that can be delayed, reducing the austenitization temperature. However, the austenitization temperature must also be high enough to decompose substantially all of the iron carbides (cementite) in the steel composition. If the austenitization temperature is not high enough, large cementite particles can remain in the final microstructure of the steel, which decreases the hardness of the steel. Thus, to improve the hardness of the steel, the austenitizing temperature is preferably selected to be just above the minimum value that is necessary to dissolve the cementite. Although temperatures higher than this minimum can guarantee cementite decomposition, they can produce excessive grain growth.
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11/40 [0023] For this reason, a preferred temperature range for austenitization is provided in each condition. The preferred range depends on the iron carbide size of the initial microstructure. In one embodiment, if the steel is in a hot-rolled condition (for example, the case for the first austenitizing treatment), the minimum temperature will preferably be high enough to dissolve the large carbides that appear in the initial microstructure (for example, about 900 ° C to about 950 ° C). If the material is in the tempering condition (for example, the case of a second austenitization carried out without intermediate tempering), there are substantially no cementite carbides present in the initial microstructure, thus, the minimum austenitization temperature is preferably lower (for example, about 880 ° C to about 930 ° C).
[0024] These observations can be used to reduce the austenitization temperature for the refining of the steel microstructure. If an intermediate temper is performed, cementite carbides can be precipitated during the temper, resulting in a minimum increase in austenitization temperature compared to the ideal case of the quench condition without cementite carbides substantially.
[0025] However, during industrial processing, it is not possible or feasible to perform a double austenitization and tempering procedure without intermediate tempering. Therefore, austenitizing, tempering and tempering operations can be repeated instead. When performing a
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12/40 tempering, reducing the tempering temperature is desirable in order to avoid the precipitation of large carbides, which need a higher austenitization temperature to be dissolved. For this reason, the tempering temperature is limited to less than about 550 ° C.
[0026] The metallic composition of the present disclosure preferably comprises an alloy of steel that includes not only carbon (C), but also manganese (Mn), silicon (Si), chromium (Cr), molybdenum (Mo), niobium ( Nb) and aluminum (Al). In addition, one or more of the following elements can be optionally present and / or added: nickel (Ni), vanadium (V), titanium (Ti) and calcium (Ca). The rest of the composition can include iron (Fe) and impurities. In certain embodiments, the concentration of impurities can be reduced to as low an amount as possible. Impurity embodiments may include, but are not limited to, sulfur (S), phosphorus (P), copper (Cu), nitrogen (N), lead (Pb), tin (Sn), arsenic (As), antimony (Sb ) and bismuth (Bi). Elements within embodiments of the steel composition can be provided as below in Table 1, where the concentrations are in% by weight, unless otherwise specified.
TABLE 1 - STEEL COMPOSITION
Element Composition range(% by weight) Preferred composition range (% by weight) Minimum Maximum Minimum Maximum
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Ç 0.20 0.30 0.24 0.27 Mn 0.30 0.70 0.45 0.55 Si 0.10 0.30 0.20 0.30 s 0 0.10 0 003 P 0 0.015 0 0.010 Cr 0.90 1.50 0.90 1.0 Mo 0.60 1.0 0.65 0.70 Ni 0 0.50 0 0.15 Nb 0.020 0.040 0.025 0.030 V 0 005 0 005 You 0 0.010 0 0.010 Ass 0 0.30 0 0.15 Al 0.01 0.04 0.01 0.04 Here 0 0.05 0 0.05 N 0 0.0080 0.01 0.0060
[0027] C is an element whose addition to the steel composition, inexpensively, increases the toughness of the steel. In some embodiments, if the C content of the steel composition is less than about 0.20%, it can be difficult to obtain the desired toughness in the steel. On the other hand, in some
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14/40 embodiments, if the steel composition has a C content greater than about 0.30%, the hardness can be impaired. Therefore, in one embodiment, the C content of the steel composition can vary within the range of about 0.20% to about 0.30%, preferably within the range of about 0.24% to about 0 , 27%.
[0028] Mn is an element whose addition to the steel composition can be effective to increase temperability, toughness and hardness. In some embodiments, if the Mn content of the steel composition is less than about 0.30%, it may be difficult to obtain the desired toughness in the steel. However, in some embodiments, if the Mn content of the steel composition exceeds about 0.7%, band structures within the steel may become marked and the steel's hardness may decrease. Accordingly, in one embodiment, the Mn content of the steel composition can vary within the range of about 0.30% to about 0.7%, preferably within the range of about 0.45% to about 0.55%.
[0029] Si is an element whose addition to the steel composition has a deoxidizing effect during the steelmaking process and also increases the toughness of the steel. In some embodiments, if the Si content of the steel composition exceeds about 0.30%, the hardness and conformability of the steel may decrease. Therefore, in one embodiment, the Si content of the steel composition can vary within the range of about 0.10% to about 0.30%, preferably within the range of about 0.20% to about 0 , 30%.
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[0030] s is an element in impurity whose presence at composition in steel cause the decrease gives hardness and The steel workability. Like this, in some achievements, O content of s gives composition of steel is limited to less than or equal to in about 0.010%, in preference to less than or equal to in about 0.003%.[0031] P is an element in impurity whose presence at
steel composition causes the hardness of the steel to decrease. Thus, in some embodiments, the P content of the steel composition is limited to less than or equal to about 0.015%, preferably less than or equal to about 0.010%.
[0032] Cr is an element whose addition to the steel composition increases the hardenability and hardness and tempering of the steel. Therefore, Cr is desirable to achieve high levels of hardness. In one embodiment, if the Cr content of the steel composition is less than about 0.90%, it can be difficult to obtain the desired toughness. In other embodiments, if the Cr content of the steel composition exceeds about 1.50%, it can decrease the hardness of the steel. Therefore, in some embodiments, the Cr content of the steel composition can vary within the range of about 0.90% to about 1.50%, preferably within the range of about 0.90% to about 1 , 0%.
[0033] Mo is an element whose addition to the steel composition is effective in increasing the toughness of the steel and also helps in slowing the softening during tempering. Additions of Mo to the steel composition can also reduce phosphorus segregation to the grain boundaries, improving hardness at intergranular cracking. In one embodiment, if the Mo content
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16/40 in the steel composition is less than about 0.60%, it can be difficult to obtain the desired toughness in the steel. However, this ferroalloy is expensive, making it desirable to reduce the maximum Mo content within the steel composition. Therefore, in some embodiments, the Mo content within the steel composition can vary within the range of about 0.60% to about 1.00%, preferably within the range of about 0.65% to about 0.70%.
[0034] Ni is an element whose addition to the steel composition is optional and can increase the toughness and hardness of the steel. However, Ni is very expensive and, in some embodiments, the Ni content of the steel composition is limited to less than or equal to about 0.50%, preferably less than or equal to about 0.15%.
[0035] Nb is an element whose addition to the steel composition can refine the austenitic grain size of the steel during hot rolling, with the subsequent increase in both toughness and hardness. Nb can also precipitate during tempering, increasing the toughness of the steel by hardening the dispersion particle. In one embodiment, if the Nb content of the steel composition is less than about 0.020%, it can be difficult to obtain the desired combination of toughness and toughness. However, in other embodiments, if the Nb content is greater than about 0.040%, a dense distribution of precipitates can form which can compromise the hardness of the steel composition. Thus, in one embodiment, the Nb content of the steel composition can vary within the range of about 0.020% to about
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0.040%, preferably within the range of about 0.025% to about 0.030%.
[0036] V is an element whose addition to the steel composition can be used to increase the hardness of the steel by carbide precipitations during tempering. However, in certain embodiments, V can be omitted from the steel composition. In one embodiment, when present, if the V content of the steel composition is greater than about 0.005%, a large volume fraction of vanadium carbide particles can be formed with a reduction in the hardness of the steel. Therefore, in some embodiments, the maximum V content of the steel composition may be less than or equal to about 0.005%.
[0037] Ti is an element whose addition to the steel composition can be used to refine the austenitic grain size. However, in certain embodiments, Ti can be omitted from the steel composition. In addition to embodiments of the steel composition when Ti is present and in concentrations greater than about 0.010%, coarse TiN particles can be formed in a way that decreases the hardness of the steel. Therefore, in certain embodiments, the maximum Ti content of the steel composition can be less than or equal to about 0.010%.
[0038] Cu is an impurity element that is not required in certain embodiments of the steel composition. However, depending on the steelmaking process, the presence of Cu may be inevitable. Thus, in certain embodiments, the Cu content of the steel composition can be limited to less than
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18/40 which is about 0.30%, preferably less than or about 0.15%.
[0039] Al is an element whose addition to the steel composition has a deoxidizing effect during the steelmaking process and further refines the grain size of the steel. In one embodiment, if the Al content of the steel composition is less than about 0.010%, the steel may be susceptible to oxidation, with high levels of inclusions. In other embodiments, if the Al content of the steel composition is greater than about 0.040%, coarse Al precipitates can be shaped to decrease the hardness of the steel. Therefore, the Al content of the steel composition can vary within the range of approximately 0.010% to about 0.040%.
[0040] Ca is an element whose addition to the steel composition is optional and can improve hardness by modifying the shape of sulfide inclusions. Thus, in certain embodiments, the minimum calcium content of the steel can satisfy the Ca / S ratio> 1.5. In other embodiments of the steel composition, excessive Ca is unnecessary and the steel composition may include a Ca content of less than or equal to about 0.05%.
[0041] The levels of unavoidable impurities, including, but not limited to, S, P, N, Pb, Sn, As, Sb, Bi and the like, are preferably kept as low as possible. However, the mechanical properties (for example, toughness, hardness) of steels formed from embodiments of the steel compositions of the present disclosure may not be substantially reduced as long as these impurities are
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19/40 maintained below the selected levels. In one embodiment, the N content of the steel composition can be less than or equal to approximately 0.008%, preferably less than or equal to approximately 0.006%. In another embodiment, the Pb content of the steel composition can be less than or equal to about 0.005%. In another embodiment, the Sn content of the steel composition can be less than or equal to about 0.02%. In a further embodiment, the As content of the steel composition can be less than or equal to about 0.012%. In another embodiment, the Sb content of the steel composition can be less than or equal to about 0.008%. In another embodiment, the Bi content of the steel composition may be less than or equal to about 0.003%.
[0042] In one embodiment, the tubular bars can be shaped using the steel composition shown above in Table 1. The tubular bars can preferably have a selected wall thickness within the range of about 4 mm to about 25 mm. In one embodiment, the tubular metal bars can be seamless. In an alternative implementation, the tubular metal bars may contain one or more seams.
[0043] Embodiments of 100. 120. 140 methods of producing high hardness metal tubular bars are illustrated in Figures 1A-1C. It can be understood that methods 100, 120, 140 can be modified to include more or less steps than those illustrated in Figures 1A-1C without limitation.
[0044] With respect to Figure 1A, in operation 102, the steel composition is shaped and converted into a billet
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20/40 metallic. In operation 104, the metallic billet may be hot, formed in a tubular bar. In operations of 106 (e.g. 106A, 106B, 106C), the shaped tubular bar can be subjected to heat treatment. In operation 110, finishing operations can be performed on the bar.
[0045] Operation 102 of method 100 preferably comprises the fabrication of the metal and the production of a solid metal billet capable of being drilled and laminated to form a tubular metal bar. In one embodiment, the metal can include steel. In other embodiments, selected scrap iron and steel sponge can be used to prepare the raw material for the steel composition. It can be understood, however, that other sources of iron and / or steel can be used for the preparation of the steel composition.
[0046] Primary metallurgy can be performed using an electric arc furnace to melt steel, decrease phosphorus and other impurities, and reach a selected temperature. Casting and deoxidation, and addition of alloying elements can still be performed.
[0047] One of the main objectives of the steel production process is to refine iron by removing impurities. In particular, sulfur and phosphorus are harmful to steel because they degrade the mechanical properties of steel. In one embodiment, the secondary metallurgy can be carried out in a ladle furnace and a deburring station after the primary metallurgy to perform specific purification steps.
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21/40 [0048] During these operations, very low levels of sulfur can be achieved within the steel, the calcium inclusion treatment as understood in the metallurgical technique can be carried out, and the inclusion flotation can be performed. In one embodiment, inclusion flotation can be accomplished by bubbling inert gases into the ladle furnace to force inclusions and impurities to float. This technique can produce a fluid slag capable of absorbing impurities and inclusions. In this way, a high quality steel containing the desired composition with a low inclusion content can result. Following the production of fluid slag, the steel can be cast into a solid round billet of substantially uniform diameter along the steel axis.
[0049] The billet thus manufactured can be formed into a tubular bar by means of thermal forming processes 104. In one embodiment, a solid, cylindrical billet of clean steel can be heated to a temperature of about 1,200 ° C to 1,300 ° C, preferably at about 1,250 ° C. The billet can also be subjected to a rolling mill. Inside the laminator, the billet can be drilled, in certain preferred embodiments using the Manessmann process, and hot rolling can be used to substantially reduce the outside diameter and the thickness of the outside wall of the pipe, while the length is increased substantially. In certain embodiments, the Manessmann process can be performed at temperatures of around 1,200 ° C. The hollow bars obtained can also be hot rolled at temperatures within the range between about 1,000 ° C to about 1,200 ° C in a continuous rolling mill.
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22/40 mandrel retained. The exact sizing can be done by a sizing laminator and the seamless tubes cooled in the air around room temperature in a cooling bed.
[0050] In a non-limiting example, a solid bar that has an outside diameter within the range between about 145 mm to about 390 mm can be hot formed, as discussed above, in a tube that has an outside diameter inside the range between about 39 mm to about 275 mm, and the wall thickness within the range between about 4 mm to about 25 mm. The length of the tubes may vary as needed. For example, in one embodiment, the length of the tubes can vary within the range of about 8 m to about 15 m.
[0051] In this way, a metal tubular bar, with straight sides, having a composition within the ranges illustrated in Table 1 can be provided.
[0052] In operations 106A-106C, the shaped metal tubular bar can be subjected to heat treatment. In operation 106A, a shaped tubular bar as discussed above can be heated to substantially completely austenitize the tubular bar microstructure. A tubular bar that is substantially completely austenitized may comprise more than about 99.9% by weight of austenite based on the total weight of the tubular bar. The tubular bar can be heated to a maximum temperature selected within the range between about 880 ° C and about 950 ° C. The heating rate during the first austenitization operation
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23/40 can vary within the range of about 15 ° C / min to about 60 ° C / min. The tubular bar can be heated further up to the maximum temperature for a period within the range of about 10 minutes to about 30 minutes.
[0053] Following the waiting period, the tubular bar can be subjected to the 106B tempering operation. In one embodiment, quenching can be performed using a water spray system (for example, quench nozzles). In another embodiment, the quench can be carried out using a pool of stirred water (for example, tank) in which additional heat extraction is obtained by a jet of water directed to the inside of the pipe. In any case, the tubular bar can be cooled at a rate between approximately 15 ° C / s to 50 ° C / s to a temperature preferably not greater than 150 ° C. The microstructure of the steel composition, after the tempering operation 104, comprises at least about 95% of martensite, with the remainder of the microstructure comprising substantially bainite.
[0054] Following the austenitizing and tempering operations 106A, 106B, the tubular bar can then be subjected to a 106C tempering operation. During the 106C tempering operation, the tubular bar can be heated to a temperature within the range of between 450 ° C and 550 ° C. The heating rate during the 106C tempering operation can vary within the range of about 15 ° C / min to about 60 ° C / min. The tubular bar can be heated further up to the maximum temperature for a period within the range of about 10 minutes to about 40 minutes. When the selected maximum temperature is reached, the tubular bar can be
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24/40 maintained at that temperature for a period within the range of about 5 minutes to about 30 minutes.
[0055] Due to the low tempering temperatures, the final microstructure of the steel composition after the 106C tempering operation comprises slightly tempered martensite having a fine carbide distribution. This microstructure is illustrated in Figures 2A-2B. As illustrated in Figure 2, tempered martensite is composed of a matrix of ferrite (for example, dark gray phases) and various types of carbides (light gray particles).
[0056] Regarding morphology, two types of carbides present in the microstructure were observed, approximately spherical and elongated. With regard to spherical carbides, it was observed that the maximum size (for example, larger dimension such as diameter) was about 150 nm. Regarding the elongated carbides, it was observed that the maximum size was about 1 pm in length and about 200 nm in thickness.
[0057] The hot rolled tube can then be subjected to different finishing operations. Non-limiting examples of these operations may include cutting the tube to length and cutting the ends of the tube, straightening the tube using rotary straightening equipment, if necessary, and non-destructive testing by a plurality of different techniques, such as electromagnetic testing or ultrasound testing . In one embodiment, the tubular bars can be straightened at a temperature not lower than
Petition 870190011852, of 02/02/2019, p. 27/61
25/40 quench temperature reduced by 50 ° C and then cooled in air to room temperature in a cooling bed.
[0058] Advantageously, seamless steel tubes obtained according to the method 100 embodiments discussed above can be used in applications including, but not limited to, drilling gun carriers in the oil and gas industry. As discussed in greater detail below, mechanical tests have established that steel tube embodiments exhibit a yield stress of about 165 ksi (measured according to ASTM E8, Standard Test Methods for Tension Testing of Metallic Materials, which is incorporated here by reference in full) and a V-notch Charpy energy at room temperature, measured according to ASTM E23 (Standard Test Methods for Notched Bar Impact Testing of Metallic Materials, which is incorporated here by reference in full) of at least about 80 Joules / cm ² for samples taken in the LC direction and at least about 60 Joules / cm ² for samples taken in the CL direction.
[0059] The good combination of toughness and hardness obtained in embodiments of the steel composition is attributed, at least in part, to the combination of the steel composition and the microstructure. In one aspect, the relatively small size of the carbides (for example, spherical carbides less than or equal to about 150 nm and / or elongated carbides of about 1pm or less in length and about 200 nm or less in thickness) increases the toughness of the steel composition by hardening the dispersion particle without harming
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26/40 strongly the hardness. On the other hand, large carbides can easily nuclear fissures.
[0060] In alternative embodiments, one of the 120 or 140 methods as illustrated in Figures 1B and 1C can be employed to manufacture seamless steel tubes when the increase in toughness is desired. Methods 120 and 140 differ from each other and method 100 in terms of heat treatment operations carried out on the seamless steel tube. As discussed in more detail below, the embodiments of heat treatment operations 126 (of method 120) comprise repeated austenitization and tempering operations, followed by tempering. Embodiments of heat treatment operations 146 (of method 140) comprise repeated sequences of austenitization, quenching and tempering. In other respects, the metal fabrication and molding, hot forming and finishing operations of methods 100. 120 and 140 are substantially the same.
[0061] With respect to method 120, heat treatment 126 may comprise a first austenitizing / tempering operation 12A which may include heating and tempering a shaped tubular bar, as discussed above, in the austenitic range. The conditions under which austenitization is performed during the first austenitization / tempering operation 126A can be designated as A1. The conditions under which tempering is performed during the first 166A austenitization / tempering operation can be designated as Q1.
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27/40 [0062] In one embodiment, the first austenitization and tempering parameters A1 and Q1 are selected so that the microstructure of the tubular bar, after undergoing the first austenitization / tempering operation 126A, comprises at least about 95% martensite with the remainder including substantially only bainite. In other embodiments, the first austenitizing and quenching parameters A1 and Q1 can also produce a microstructure that is substantially free of carbides. In certain embodiments, a microstructure that is substantially free of carbides may include a total carbide concentration of less than approximately 0.01% by weight based on the total carbide weight of the tubular bar. In other embodiments, the average grain size of the tubular bar after the first austenitizing and quenching operations 126A can fall within the range between approximately 10 pm to approximately 30 pm.
[0063] In one embodiment, the first austenitization parameters A1 can be selected in order to substantially fully austenitize the microstructure of the tubular bar. A tubular bar that is substantially fully austenized can include more than approximately 99.9% by weight of austenite based on the total weight of the tubular bar. The tubular bar can be heated to a maximum selected temperature within the range of about 900 ° C to about 950 ° C. The heating rate during the first 126A austenitization operation can vary within the range of about 30 ° C / min to about 90 ° C / min. The tubular bar can be heated further up to the
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28/40 maximum temperature for a period within the range of about 10 minutes to about 30 minutes.
[0064] The tubular bar can subsequently be maintained at the maximum temperature selected for a selected waiting time within the range of about 10 minutes to about 30 minutes. The relatively low austenitization temperatures employed in the embodiments of the revealed heat treatments, within the range of about 900 ° C to about 950 ° C, are used to contain grain growth as much as possible, promoting the microstructural refinement that can give lead to improvements in hardness. For such austenitizing temperatures, the austenitizing temperature range of about 900 ° C to about 950 ° C is also sufficient to substantially provide complete dissolution of the cementite carbides. Within this temperature range, complete dissolution of carbides rich in Nb and Ti, even when extremely long waiting times are used, is generally not achieved. Cementite carbides, which are larger than Nb and Ti carbides, can damage hardness and reduce toughness due to carbon retention.
[0065] Following the waiting period, the tubular bar can be tempered. In one embodiment, quenching during austenitization / quenching operations 126A can be performed by a water spray system (e.g. quench nozzles). In another embodiment, the quenching can be carried out using a pool of stirred water (e.g., tank) in which the additional thermal extraction is obtained by a jet of water directed to the inside of the tube.
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29/40 [0066] The embodiments of the Q1 tempering parameters are as follows. The tubular bar can be cooled at a rate between approximately 15 ° C / s to 50 ° C / s to a temperature, preferably not greater than about 150 ° C.
[0067] The second austenitization / tempering operation 126B may include heating and tempering the shaped tubular bar, as discussed above, in the austenitic interval. The conditions under which austenitization is carried out during the second austenitization / rapid cooling operation 126A can be designated as A2. The conditions under which tempering is performed during the second austenitization / tempering operation 126A can be designated as Q2.
[0068] In one embodiment, the second austenitization and tempering parameters A2 and Q2 can be selected so that the microstructure of the tubular bar after undergoing the second austenitization / tempering operation 126B comprises at least about 95% martensite . In other embodiments, the austenitizing and tempering parameters A2 and Q2 can also produce a microstructure that is also substantially free of carbides.
[0069] In additional embodiments, the average grain size of the tubular bar after the second austenitizing / quenching operations 126B may be less than that obtained after the first austenitizing and quenching operations 126A. For example, the grain size of the tube after the second austenitizing / tempering operations 126B may fall within the range of about 5 pm to about 15 pm. That
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30/40 microstructural refinement can improve the toughness and / or hardness of the tubular bar.
[0070] In one embodiment, the second A2 austenitization parameters are as follows. The tubular bar can be heated to a maximum austenitizing temperature lower than that used in the first 126A austenitization / tempering operations to further refine the microstructure grain size. The second A2 austenitization operation takes advantage of the carbide dissolution achieved during the first 106A (A1 / Q1) austenitization / tempering operations. As substantially all iron carbides (eg cementite particles) are dissolved in the microstructure after the first austenitizing and tempering operations 126, lower austenitizing temperatures can be used during the second austenitizing and tempering operations 126B with agent reduction in grain size (grain refinement). In one embodiment, the second A2 austenitization operation can be performed at a selected temperature within the range of about 880 ° C to about 930 ° C. The heating rate during the second A2 austenitization operation can vary within the range of about 15 ° C / min to about 60 ° C / min. The tubular bar can then be maintained at the maximum temperature selected for a selected waiting time within the range of about 10 to about 30 minutes.
[0071] Following the waiting period, the tubular bar can be tempered Q2. In one embodiment, tempering during austenitization / tempering operations 126B can be performed by a water spray system (for example,
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31/40 (example, tempering nozzles). In another embodiment, the quenching can be carried out using a pool of stirred water (e.g., tank) in which the additional thermal extraction is obtained by a jet of water directed to the inside of the tube.
[0072] The embodiments of the Q2 tempering parameters are as follows. The tubular bar can be cooled at a rate between approximately 15 ° C / s to about 50 ° C / s to a temperature, preferably not greater than about 150 ° C.
[0073] Following the first and second austenitization / tempering operations 126A, 126B, the tubular bar can then be subjected to a tempering operation 126C, also referred to here as (T). During the tempering operation 126C, the tubular bar can be heated to a temperature within the range between about 450 ° C and about 550 ° C. The heating rate during the 106C tempering operation can vary within the range of about 15 ° C / min to about 60 ° C / min. The tubular bar can also be heated up to the maximum temperature for a time in the range of about 10 minutes to about 40 minutes. Upon reaching the selected maximum temperature, the tubular bar can be maintained at this temperature for a period within the range of about 5 minutes to about 30 minutes.
[0074] Tubular bars may also be subject to finishing operations 130. Examples of finishing operations 130 may include, but are not limited to, straightening. Straightening can be carried out at a temperature no lower than the reduced quenching temperature
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32/40 at 50 ° C. Subsequently the straightened tube can be cooled in air to room temperature in a cooling bed.
[0075] In an alternative embodiment, the shaped tubular bar can be subjected to method 140 which employs 146C heat treatment operations. In heat treatment operations 146C, the first austenitizing and tempering operations 146A (A1) and (Q1) are followed by a first tempering operation 146B (T1), by second austenitizing and tempering operations 146C (A2) and (Q2) and second 146D tempering operation (T2). The first and second austenitizing and tempering operations 146A and 146C can be performed, as discussed above, in relation to the first and second austenitizing and tempering operations 126A and 126B. The first (T1) and the second (T2) tempering operations 146B and 146D can also be performed, as discussed above, in relation to the first tempering operation 106C.
[0076] The microstructure resulting from methods 120 and 140 may be similar to that resulting from method 100. For example, in an embodiment after the first austenitizing and tempering operations 126A and 146A, the average grain size can vary in the range of between about from 10 pm to about 30 pm. In another embodiment, after the second austenitizing and tempering operations 126C and 146C, the average grain size can vary within the range of about 5 pm to about 15 pm. In other embodiments, a fine distribution of carbides may be present within the microstructure after tempering operations 126C, 146D. For example,
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33/40 spherical and elongated carbides can be present in the microstructure, with the maximum size of spherical particles being less than or equal to about 150 nm and the maximum size of elongated carbides being less than or equal to about 1 pm in length and less than or equal to about 200 nm in thickness.
[0077] Advantageously, seamless steel tubes and tubes shaped according to embodiments of methods 120 and 140 can be useful for applications including, but not limited to, drilling gun carriers in the oil and gas industry. For example, in one embodiment, the tubular bars and shaped tubes of embodiments of the steel composition may have a yield stress of at least about 170 ksi (approximately 1,172 MPa), as measured according to the ASTM standard E8. In another embodiment, the tubular bars and shaped tubes of embodiments of the steel composition may exhibit the V-notch Charpy impact energies at a temperature above about 80 J / cm ² in the LC direction and about 60 J / cm ² in the CL direction, as measured according to the ASTM E23 standard. This good combination of properties is due, at least in part, to the refined grain size and the relatively small size of the carbides within the microstructure.
[0078] Beneficially, in certain embodiments, these results can be achieved without adding vanadium. Vanadium is known to increase carbide precipitation toughness during tempering, but can compromise hardness.
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34/40
EXAMPLES [0079] In the following examples, the tensile and impact properties of shaped steel tubes using embodiments of the metallurgy method discussed above are illustrated. The conformed steel tubes were tested after heat treatments of austenitization, quenching and tempering (A + Q + T) (Conditions 1 and 2), double austenitization and quenching (A1 + Q1 + A2 + Q2 + T) followed by tempering ( Condition 3). The steel tubes tested had an outside diameter of approximately 114.3 mm and a wall thickness of approximately 8.31 mm, unless otherwise indicated. Experiments were carried out on samples having approximately the composition and heat treatments of Tables 2 and 3, respectively.
TABLE 2 - COMPOSITION OF SAMPLE SPECIMENS
Heat Ç Mn Si Cr Mo Ni NbTHE 0.25 0.47 0.25 0.94 0.67 0.016 0.028 B 0.25 0.49 0.25 0.95 0.70 0.01 0.027 Heat Ass s P Al You V N THE 0.029 001 008 0.027 001 001 0.0035 B 0.056 001 008 0.016 001 001 0.0039
TABLE 3 - HEAT TREATMENTS OF SAMPLE SPECIMENS
Condition Heat Treatment TO 1 A2 (° C) T (° C)
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35/40
Thermal (° C) 1 THE Single 880 - 460 2 B Single 910 - 460 3 B Austenitizationdouble 910 890 460
[0080] Measurements of toughness and impact properties were performed in between 3 to 5 tubes for each condition. For each tube, tensile tests were performed in duplicate and impact tests were performed in triplicate at around room temperature. It can be understood that the examples presented below are for illustrative purposes and are not intended to limit the scope of this disclosure.
Example 1 - Tensile properties and impact energies at room temperature [0081] The toughness and elongation of the steels having the compositions indicated above in Tables 2 and 3 were measured according to the ASTM E8 standard at room temperature. The Charpy energies of the steels in Tables 2 and 3 were measured according to the ASTM E23 standard around room temperature and represent a measure of the hardness of the materials. Charpy tests were performed on samples with dimensions of approximately 10 x 7.5 x 55 mm taken longitudinally (LC) from the tubes. The average tensile hardness, the yield limit stress, the elongation and the energies of
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36/40
V-notch charpy (CVN) measured for each condition are reported in Table 4 and average values per tube are reported in Figure 3.
TABLE 4 - AVERAGE TRACTION IMPACT PROPERTIES
Condition YS (ksi) UTS (ksi) YS / UTS El (%) CVN / cm ² (Joules) 1 172 ± 3 182 ± 3 0.95 14 ± 3 91 ± 5 2 176 ± 2 188 ± 2 0.93 14 ± 1 92 ± 5 3 180 ± 2 189 ± 1 0.95 13 ± 2 97 ± 5
[0082] For each of the tested conditions, the limit yield stress was observed to be greater than or equal to about 165 ksi and the tensile strength was observed to be greater than or equal to approximately 170 ksi. Failure elongation for each of the conditions tested was still found to be greater than or equal to about 10%. In other embodiments, it was observed that the yield stress was greater than about 170 ksi, it was observed that the tensile strength was greater than or equal to about 180 ksi, and it was found that the elongation at failure was greater than or equal to about 13%. In certain embodiments, the V-notch impact energies measured around ambient temperature were greater than approximately 65 J / cm ² for each of the conditions tested. In other embodiments, the Charpy energies to
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37/40 room temperature were greater than or equal to about 90 J / cm ² .
[0083] The best combination of tensile properties and hardness was observed for condition 3, which corresponded to double austenitization. This condition presented the highest yield stress (approximately 189 ksi) and CVN at room temperature (approximately 97 J / cm ² ). The improvement in the yield strength and hardness is attributed to the microstructural refinement achieved by double austenitization / tempering operations.
Example 2 - Complementary impact energy studies
Additional impact energy investigations were carried out on steel tube samples conformed to condition 1 from about -60 ° C to around room temperature in order to identify the brittle ductile transition temperature of the sample compositions in steel . For these measurements,
longitudinal directions ( LC) and transversal (CL) . The tests in Charpy were performed on samples with dimensions in about 10 x 7.5 x 55 mm in LC direction and in about 10 x 5 x 55 mm in the direction CL. The energies in Notch charpy in V averages for each condition are
reported in Table 5.
TABLE 5 - AVERAGE HARDNESS OF CONDITION 2 SAMPLES
Size / Orientation T (° C) CVN (J) CVN (J / cm ² ) Ductile Area (%)
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38/40
10 x 7.5 x 55 LC RT 71 (73, 71,73) (73, 72,75) 95 100 (100, 100,100) (100, 100, 100) 0 64 (66, 65,60) 85 94 (97, 94, 90) -20 48 (52, 41,51) 64 71 (74, 64, 76) -40 34 (31, 38,33) 45 44 (38, 50, 45) -60 27 (30, 26,28) (29, 28,24) 36 32 (33, 30, 32) (35,33, 27)10 x 5 x 55 CL RT 37 (36, 37,37) (37, 37,35) 74 100 (100, 100,100) (100, 100, 100) 0 38 (36, 39,39) 76 100 (100, 100, 100) -20 30 (31, 31,28) 60 100 (100, 100, 100) -40 25 (21, 23,32) 50 75 (73, 65, 91) -60 15 (17, 16, 30 31 (40, 34, 34) (27,
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39/40
15) (13, 14,12)30, 18)
[0085] As shown in Table 5, LC Charpy samples around room temperature (RT) showed energies greater than about 80 J / cm ² and approximately 100% ductile crack, as seen from the crack surface. The samples of CL Charpy showed energies of more than about 60 J / cm ² and approximately 100% ductile fracture. As the test temperature decreased from around room temperature to about -60 ° C, the energies of LC and CL Charpy dropped to about half to approximately 30 - 36 J / cm ² . At the same time, the part of the crack surface subjected to a ductile crack has decreased by approximately two-thirds in each geometry.
[0086] From the results, it can be seen that the ductile to brittle transformation temperature (DBTT) is between -20 ° C and -40 ° C for longitudinally oriented samples due to the large reduction in the ductile area observed between about -20 ° C and about -40 ° C in the LC orientation (from about 71% to about 44%). It can also be observed that DBTT is between about 40 ° C and -60 ° C for transversely oriented samples (CL) due to the large reduction in the ductile area observed between about -40 ° C and about -60 ° C ( from about 75% to about 31%).
[0087] Although the preceding description has shown, described and pointed out the fundamental innovative characteristics of the present teachings, it should be understood that several omissions, substitutions and changes in the form of
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40/40 detail of the device as illustrated, as well as its uses, can be made by those qualified in the state of the art without departing from the scope of application of the present teachings. Therefore, the scope of the present teachings should not be limited to the preceding discussion, but should be defined by the appended claims.

权利要求:
Claims (19)
[1]
1. Steel tube characterized by comprising:
0, 20 % in Weight up until 0, 30 O.% in Weight in carbon; 0, 30 O.% in Weight up until 0, 70 O.% in Weight in manganese; 0, 10 O.% in Weight up until 0, 30 O.% in Weight in silicon; 0, 90 O.% in Weight up until 1, 50 O.% in Weight in chrome; 0, 60 O.% in Weight up until 1, 00 O.% in Weight in molybdenum;
0.020% by weight to 0.040% by weight of niobium; and
0.01 % by weight up until 0, 04% in aluminum weight; and still understand at least one in: equal or any less of what 0.50% by weight of nickel; equal or any less of what 0.005% by weight of vanadium; equal or any less of what 0.010% by weight of titanium; equal or any less of what 0.05% by weight of calcium;
where the steel pipe is processed to have a yield stress greater than 1138.5 MPa and where the V-notched Charpy energy is greater than or equal to 80 J / cm ² in the longitudinal direction and greater than or equal to about 60 J / cm ² in the transverse direction at room temperature.
[2]
2. Steel tube according to claim
1, characterized by further comprising:
0, 24 % in Weight up until 0, 27 O.% in Weight in carbon; 0, 45 O.% in Weight up until 0, 55 O.% in Weight in manganese; 0, 20 O.% in Weight up until 0, 30 O.% in Weight in silicon;
up until
0.90% by weight
1.0% by weight of chromium;
0.65
O.
% by weight up to
0.70% by weight of molybdenum; and
0.025% by weight to 0.030% by weight of niobium.
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2/5
[3]
3. Steel tube according to claim 1, characterized by the fact that the tensile strength of the steel tube is greater than 1173 MPa.
[4]
4. Steel tube according to claim 1, characterized by the fact that the steel tube exhibits 100% ductile fracture at room temperature.
[5]
5. Steel tube according to claim 1, characterized by the fact that the microstructure of the steel tube comprises more than or equal to 95% of martensite by volume.
[6]
6. Steel tube according to claim 5, characterized by the fact that the rest of the microstructure consists of bainite.
[7]
Steel tube according to claim 1, characterized by the fact that the steel tube has a plurality of approximately spherical carbides having a greater dimension of less than or equal to 150 pm.
[8]
Steel tube according to claim 1, characterized in that the steel tube has a plurality of elongated carbides having a length less than or equal to about 1 pm and a thickness less than or equal to 200 nm.
[9]
Steel tube according to claim 1, characterized by the fact that the steel tube has an average grain size between 5 pm and 15 pm.
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3/5
[10]
10. Method for the production of a steel tube, characterized by comprising:
providing a carbon steel composition as defined in claim 1;
forming the steel composition in a tube;
heating the shaped steel tube in a first heating operation to a first temperature;
tempering the shaped steel tube in a first tempering operation from the first temperature at a first rate such that the microstructure of the tempered steel has more than or equal to 95% of martensite by volume;
tempering the shaped steel tube in a first tempering operation after the first temp operation by heating the shaped steel tube to a second temperature below 550 ° C;
where the steel tube after tempering has a yield stress greater than 1138.5 MPa and where the V-notched Charpy energy is greater than or equal to 80 J / cm2 in the longitudinal direction and 60 J / cm2 in the direction transversal at room temperature.
[11]
11. Method according to claim 10, characterized by the fact that the first temperature is between 880 ° C and 950 ° C for 10 to 30 minutes.
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4/5
[12]
12. Method according to claim 10, characterized in that the second temperature is between 450 ° C and 550 ° C for 5 to 30 minutes.
[13]
13. Method according to claim 10, characterized by the fact that the grain size of the formed steel tube after the time is between 5 and 15 pm.
[14]
Method according to claim 10, characterized in that the microstructure of the steel tube comprises a plurality of approximately spherical carbides having a greater dimension of less than or equal to 150 pm after tempering.
[15]
Method according to claim 10, characterized in that the microstructure of the steel tube comprises a plurality of elongated carbides having a length less than or equal to 1 pm and a thickness less than or equal to 200 nm after tempering.
[16]
16. Method according to claim 10, characterized in that the first quenching rate is between 15 ° C / s and 50 ° C / s.
[17]
17. Method according to claim 10, characterized in that the remainder of the microstructure consists of bainite after the first tempering operation.
[18]
18. Method according to claim 10, characterized by the fact that after the first tempering operation and before the first tempering operation, the shaped steel tube
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5/5 goes through a second heating operation and a second tempering operation.
[19]
19. Method according to claim 10, characterized by the fact that after the first tempering operation, the shaped steel tube goes through a second heating operation, a second tempering operation and a second tempering operation.

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法律状态:
2018-11-06| B07A| Technical examination (opinion): publication of technical examination (opinion)|

2019-04-02| B09A| Decision: intention to grant|

2019-05-14| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 16/02/2012, OBSERVADAS AS CONDICOES LEGAIS. (CO) 20 (VINTE) ANOS CONTADOS A PARTIR DE 16/02/2012, OBSERVADAS AS CONDICOES LEGAIS |

优先权:

申请号 | 申请日 | 专利标题

US13/031,131|US8636856B2|2011-02-18|2011-02-18|High strength steel having good toughness|

US13/031,131|2011-02-18|

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