EP0651059B1 - Procédé pour la production d'acier à très haute résistance présentant une excellente résistance à la fissuration par corrosion sous contrainte - Google Patents

Procédé pour la production d'acier à très haute résistance présentant une excellente résistance à la fissuration par corrosion sous contrainte Download PDF

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Publication number
EP0651059B1
EP0651059B1 EP19930117410 EP93117410A EP0651059B1 EP 0651059 B1 EP0651059 B1 EP 0651059B1 EP 19930117410 EP19930117410 EP 19930117410 EP 93117410 A EP93117410 A EP 93117410A EP 0651059 B1 EP0651059 B1 EP 0651059B1
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EP
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Prior art keywords
temperature
point
steel
strength
stress corrosion
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP19930117410
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German (de)
English (en)
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EP0651059A1 (fr
Inventor
Yoshihiro C/O Nippon Steel Corporation Okamura
Ryota C/O Nippon Steel Corporation Yamaba
Tomoya C/O Kawasaki Steel Corporation Koseki
Ichiro C/O Kawasaki Steel Corporation Nakagawa
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JFE Steel Corp
Nippon Steel Corp
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Nippon Steel Corp
Kawasaki Steel Corp
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Priority to DE1993626152 priority Critical patent/DE69326152T2/de
Priority to EP19930117410 priority patent/EP0651059B1/fr
Publication of EP0651059A1 publication Critical patent/EP0651059A1/fr
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/001—Heat treatment of ferrous alloys containing Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite

Definitions

  • the present invention relates to a process for producing an extra-high-tensile and high-toughness steel having a yield strength of 1080 MPa or more that has a high strength despite a low carbon content and is excellent in stress corrosion resistance in a stress corrosive environment, such as sea water and salt water.
  • Examples of extra high tensile steel products having a high reliability underwater include a Ni-Cr-Mo-V-based high-toughness and extra-high-tensile steel proposed in Japanese Examined Patent Publication (Kokoku) No. 64-11105, characterized by comprising a Ni-containing steel having lowered N and O contents and capable of satisfying a requirement of Al (%) x N (%) x 10 4 ⁇ 1.5, which high-toughness and extra-high-tensile steel has a significant effect.
  • the stress corrosion cracking resistance at the welding heat affected zone in sea water is inferior to that in the air as compared with the base material, which requires further study regarding improvement in safety and reliability.
  • Japanese Examined Patent Publication (Kokoku) No. 1-51526 proposes a process for producing an extra high tensile steel having an excellent stress corrosion cracking resistance, which comprises subjecting a Ni-Mo-Nb-based steel having a Ni content of 5 to 8% to direct quenching-and-tempering.
  • the strength of the steel product is lower than that contemplated in the present invention.
  • close control is necessary from the viewpoint of the homogeneity and anisotropy of the quality in the direction of the plate thickness. Further, there is a possibility that the stability of the quality is deteriorated in the widthwise direction and longitudinal direction within the steel plate.
  • the conventional extra high tensile steel products have lower stress corrosion cracking resistance particularly at the welding-heat affected zone in sea water than in the air and are produced by processes that are disadvantageous in the homogeneity of the quality in the thicknesswise direction of the thick steel plate and the stability of the quality within the steel plate. That is, a further improvement in both the steel products and production processes has been desired in the art.
  • a steel which meets the compositional requirements of the present invention is disclosed in US-A-4 814 141 (Table 1, Steel N), specific parameters of hot working and heat treating after hot working being not mentioned therein. Such parameters, similar to those claimed, are disclosed in US-A-4 946 516, however without any specific rate of reheating being disclosed.
  • An object of the present invention is to improve the homogeneity of the quality of a thick steel product through an alleviation in the problem of the prior art, i.e., a problem of the stress corrosion cracking resistance, particularly a deterioration in the stress corrosion cracking resistance at the welding heat affected zone in sea water, together with an increase in the tensile strength.
  • the subject matter of the present invention is as follows.
  • a process for producing an extra high tensile steel having an excellent stress corrosion cracking resistance comprises the steps of: heating a slab comprising, in terms of % by weight, 0.04 to 0.09% of C, 0.01 to 0.10% of Si, 0.05 to 0.65% of Mn, 8.0 to 11.0% of Ni, 0.5 to 1.5% of Mo, 0.2 to 1.5% of Cr, 0.02 to 0.20% of V and 0.01 to 0.08% of Al with the balance consisting of iron and unavoidable impurities or a slab comprising the above-described ingredients and further comprising at least one member selected from the group consisting of 0.2 to 1.5% of Cu, 0.005 to 0.10% of Nb and 0.005 to 0.03% of Ti as strength improving elements and 0.0005 to 0.005% of Ca and 0.0005 to 0.0100% of REM (Rare earth metal) as elements having a capability of regulating the form of inclusions to a temperature between 1000°C and 1250°C, hot-rolling the slab at a temperature of Ar' point (the
  • the present inventors have conducted various studies on steel ingredients and production process, particularly on hot rolling, reheating, quenching and tempering with a view to stably producing a Ni-containing low alloy steel having a good resistance to stress corrosion cracking, particularly stress corrosion cracking at the welding-heat affected zone, in sea water or salt water and, at the same time, a high tensile strength and a high toughness and, as a result, have found that, when Mo, V and Nb are added to a Ni-containing steel having lowered C, Si and Mn contents and the Ni-containing steel is hot-rolled to sufficiently dissolve these elements in a solid solution form and reheated and quenched with controlled temperature rise rate and heating temperature range, the Mo, V and Nb dissolved in a solid solution form are precipitated during heating to form non-diffusion type reverse transformed ⁇ grains comprising a group of acicular austenites having a high dislocation density, which enables a reinforcing mechanism inherent in the Ni-containing steel to be exhibited to attain an increase
  • C is an element useful for improving the quenchability and easily increasing the strength. On the other hand, it has the greatest effect on an improvement in the stress corrosion cracking resistance of the welding-heat affected zone of the extra high tensile steel. When the content exceeds 0.09%, a significant lowering in the stress corrosion cracking resistance of the welding-heat affected zone occurs. On the other hand, when it is lower than 0.04%, the strength is unsatisfactory. For this reason, the C content is limited to 0.04 to 0.09%.
  • Si is useful for improving the strength. It is also indispensable for steel making. Si is contained in an amount of 0.01% at the smallest. In the case of a high Ni-containing steel contemplated in the present invention, when the Si content exceeds 0.10%, the temper brittleness becomes so great that the low-temperature toughness is lowered. For this reason, the Si content is limited to 0.01 to 0.10%.
  • Mn is necessary for improving the quenchability and hot workability.
  • the Mn content is less than 0.05%, the improvement effect cannot be attained.
  • the addition of Mn increases the susceptibility to temper brittleness and deteriorates the stress corrosion cracking resistance of the welding-heat affected zone, so that the Mn content should be 0.65% or less.
  • Ni is useful for enhancing the stacking fault energy, increasing the cross slip, facilitating the occurrence of stress relaxation, increasing the impact absorption energy and improving the low-temperature toughness.
  • Ni exhibits the best effect when it is present together with Mo, V and other elements contained in the steel of the present invention.
  • a grain mixture of diffusion type reverse transformed ⁇ grains comprising a massive austenite formed by dissolution of carbides with non-diffusion type reverse transformed ⁇ grains comprising a group of acicular austenites not involving the dissolution of carbides is formed, and the non-diffusion type reverse transformed ⁇ grains have a higher dislocation density than the diffusion type reverse transformed ⁇ grains and very effectively contributes to an increase in the strength.
  • Ni serves to delay the dissolution of carbides of Mo, V and other elements, which enables the group of acicular austenites to be stably maintained up to a high temperature. For this reason, Ni should be added in an amount of 8.0% or more for the purpose of ensuring the strength by taking advantage of stabilization of the non-diffusion type reverse transformed ⁇ grains at a high temperature. On the other hand, when the amount of addition of Ni exceeds 11.0%, austenite is precipitated during tempering, which deteriorates the strength and toughness. For this reason, the Ni content is limited to 8.0 to 11.0%.
  • Mo is an element useful for the precipitation hardening by tempering and the inhibition of temper brittleness and, at the same time, important to the present invention as with Ni. Specifically, since a fine carbide composed mainly of Mo precipitated in the course of heating in the step of reheating and quenching remains as an undissolved carbide up to a high temperature, the group of acicular austenites having a high dislocation density can be maintained at a high temperature, so that Mo is necessary for ensuring the strength.
  • the Mo content is less than 0.5%, the dissolution of the Mo carbide occurs in the reheating and quenching, which causes the non-diffusion type transformed ⁇ grains to be rapidly attacked by the diffusion type reverse transformed ⁇ grains, so that a contemplated strength cannot be obtained.
  • the Mo content exceeds 1.5%, the effect of improving the strength is saturated, so that the amount of coarse alloy carbides is increased to lower the toughness. For this reason, the Mo content is limited to 0.5 to 1.5%.
  • the Cr serves to improve the quenchability and is useful for ensuring the strength.
  • the Cr content should be 0.2% at the lowest. When it exceeds 1.5%, the increase in the strength is saturated and the toughness is lowered. For this reason, the Cr content is limited to 0.2 to 1.5%.
  • V is useful for forming a carbonitride in the tempering that is precipitation-hardened to ensure the strength. Further, as with Mo, V is finely precipitated during heating in the reheating and quenching to increase the stability of non-diffusion type reverse transformed ⁇ grains comprising a group of acicular austenites, which is useful for ensuring the strength.
  • V content is less than 0.02%, no contemplated strength cannot be attained, while when it exceeds 0.20%, the toughness is lowered. For this reason, the V content is limited to 0.02 to 0.20%.
  • Al is necessary for deoxidation and, at the same time, combines with N to form a nitride, AlN, that has the effect of refining the structure.
  • Al content is less than 0.01%, this effect is small.
  • it exceeds 0.08% the amount of inclusions comprising alumina becomes so large that the toughness is inhibited. For this reason, the Al content is limited to 0.01 to 0.08%.
  • At least one member selected from (Cu, Nb, Ti) and (Ca, REM) is added besides the above-described ingredients.
  • Cu, Nb and Ti exhibit an equalizing action, that is, serve to improve the strength of the steel.
  • Nb and Ti are useful also for the refinement of austenite grains.
  • the Cu, Nb and Ti contents exceed 1.5%, 0.10% and 0.03%, respectively, not only the low-temperature toughness is lowered but also the susceptibility to stress corrosion cracking is enhanced. For this reason, the Cu, Nb and Ti contents are limited to the above-described respective ranges.
  • Ca and REM (Rare earth metal) have the effect of spheroidizing nonmetallic inclusions and are useful for improving both the toughness and anisotropy.
  • the Ca and REM should be present in an amount of 0.0005% at the smallest.
  • the toughness is lowered due to an increase in the amount of inclusions.
  • the Ca and REM contents are limited to 0.0005 to 0.005% and 0.0005 to 0.0100%, respectively.
  • the steel of the present invention contains, besides the above-described ingredients, P, S, N, O and other elements as unavoidable impurities that are detrimental to the toughness and stress corrosion cracking resistance characteristic of the steel of the present invention and, therefore, the amount of these unavoidable impurities is as small as possible.
  • the contents of P, S, N and O are preferably regulated to 0.005% or less, 0.003% or less, 0.0050% and 0.0030%, respectively.
  • the production process should be proper for attaining the strength, toughness and stress corrosion cracking resistance contemplated in the present invention. Accordingly, in the process of the present invention, the rolling, cooling and reheating-quenching-tempering conditions were limited for the following reasons.
  • a slab comprising the above-described ingredients is heated to 1000 to 1250°C.
  • the slab in order to attain, besides the refinement of heated austenite grains, utilization of the strengthening by taking advantage of the above-described non-diffusion type reverse transformed ⁇ and fine precipitation in the reheating-quenching-tempering after the hot rolling, the slab should be heated to 1000°C or above to sufficiently dissolve Mo, Cr, V, Nb, etc., in a solid solution form.
  • heated austenite grains are coarsened, and it becomes difficult to refine the austenite grains in the subsequent rolling, which is causative of a lowering in the toughness.
  • the heating temperature of the slab is limited to 1000 to 1250°C.
  • the heated slab is then hot-rolled at a temperature of the Ar' transformation point and air-cooled.
  • the Ar' point is as low as 400°C
  • the above requirement can be met by simply subjecting the heated slab to conventional hot rolling.
  • the steel of the present invention has a composition having a sufficiently high quenchability, air cooling alone suffices for the formation of a martensitic single phase structure including a sufficiently large amount of dislocation.
  • non-diffusion type reverse transformed ⁇ grains contributing to strengthening are the same as the ⁇ grains after the hot rolling, if it is necessary to ensure a higher low-temperature toughness, although a lowering in the roll finishing temperature is preferred according to need for the purpose of refining the ⁇ grains by rolling-recrystallization, there is no limitation on the method.
  • the steel plate after hot rolling and air cooling is then reheated to a temperature range of from (A c3 point - 40°C) to (A c3 point + 40°C) and quenched.
  • step of heat treatment wherein reheating is effected with the martensite structure used as a precursor structure, when the steel is heated to an ⁇ - ⁇ dual phase coexisting temperature region, diffusion type reverse transformed ⁇ grains comprising an ordinary massive austenite are formed from old austenite grain boundaries while a group of acicular austenites are formed from the intragranular martensite. They coexist together with carbides and ferrite.
  • the acicular austenite is produced by non-diffusion type (martensitic) reverse transformation, it has a large amount of dislocation that contributes to an increase in the strength. Further, the heating of the steel plate to a temperature range of from (A c3 point - 40°C) to (A c3 point + 40°C) causes the group of acicular austenites to increase their area to form non-diffusion type reverse transformed ⁇ grains that are stably maintained up to a high temperature and become fine austenite grains comprising a mixture thereof with diffusion type reverse transformed ⁇ grains. When quenching is effected from this temperature region, a martensitic structure, into which further dislocation has been introduced, is formed, so that it becomes possible to produce an extra high tensile steel.
  • the reheating temperature for quenching should be in the range of from (A c3 point - 40°C) to (A c3 point + 40°C) and is preferably A c3 point ⁇ 20°C from the viewpoint of stabilizing the non-diffusion type reverse transformed ⁇ grains.
  • the above-described change in the austenite grains ( ⁇ grains) is shown in Fig. 3. Fig.
  • FIG. 3 (B) is a schematic view of a grain mixture of non-diffusion type reverse transformed ⁇ grains with diffusion type reverse transformed ⁇ grains, which grain mixture has been formed by a treatment in a reheating temperature region for quenching of from (A c3 point - 40°C) to (A c3 point + 40°C) specified in the present invention.
  • Fig. 3 (A) is a diagram showing the results for a reheating temperature region of (A c3 point - 40°C) or below
  • Fig. 3 (C) is a diagram showing the results for a reheating temperature region of (A c3 point + 40°C) or above.
  • FIG. 2 shows the results of a yield strength test on a steel plate produced by subjecting a slab having a composition of 0.06% C - 9.9% Ni - 1.0% Mo - 0.1% V to heating at 1150°C, rolling and air cooling, reheating the steel plate to 790°C with varied temperature rise rate, quenching the steel plate and temperature the quenched steel plate at 540°C. It is apparent that the strength is improved with lowering the temperature rise rate. It is reported that the non-diffusion type reverse transformed ⁇ is generally formed by rapid heating.
  • the steel having a high Ni content according to the present invention the non-diffusion type reverse transformed ⁇ is formed without rapid heating and, as opposed to the conventional common knowledge, a temperature rise rate of 120°C/min or less is advantageous from the viewpoint of increasing the strength.
  • carbides and nitrides of Mo, Cr, V, Nb, etc., precipitated during gradual heating increase the stability of the once formed non-diffusion type reverse transformed ⁇ , so that the area ratio of the non-diffusion type reverse transformed ⁇ grains contributing to strengthening is increased.
  • the steel plate after the reheating and quenching is then tempered at a temperature of an Ac 1 point or below.
  • the temperature exceeds the Ac 1 point, the strength and toughness are lowered due to the formation of unstable austenite.
  • the tempering temperature is limited to Ac 1 point or below for the purpose of sufficiently precipitation-strengthening through fine precipitation of Mo, Cr, V, Nb, etc., to provide a high strength and a high toughness.
  • the steel provided by the above-described production process has a high strength and a high toughness despite a low carbon content and an remarkably improved stress corrosion cracking resistance, particularly at the welding-heat affected zone.
  • Steels having compositions specified in Table 1 were produced by the melt process to provide slabs that were then used to produce steel plates having a thickness of 20 to 80 mm under production conditions according to the process of the present invention or comparative process specified in Table 2.
  • the mechanical properties of these base materials and the K lSCC value (limiting fracture toughness value relative to stress corrosion cracking resistance) of the base material portion and welding-heat affected zone were examined.
  • the welding was effected at a heat input of 25 kJ/cm by TIG welding.
  • the stress corrosion cracking resistance is evaluated by effecting a constant load test under this environment at a K value (a coefficient of stress necessary for preventing the occurrence of cracking at the tip of the notch) on various levels to determine a limit of K lSCC value that does not cause a fracture at a certain K value or less.
  • K value a coefficient of stress necessary for preventing the occurrence of cracking at the tip of the notch
  • a limit of K lSCC value that does not cause a fracture at a certain K value or less.
  • a notch is provided at the center of HAZ as shown in Fig. 5.
  • the thick underlined portion is outside the scope of the present invention and unsatisfactory in the properties thereof.
  • the base materials had good mechanical properties, i.e., a high strength and a high toughness, and with respect to the stress corrosion cracking resistance as well, both the base material and welding heat affected zone had a sufficiently high K lSCC value.
  • Fig. 4 is a graph showing the K lSCC values of the steel of the present invention, comparative steel and conventional materials. From this drawing, it is apparent that the K lSCC value of the steel of the present invention is on a level significantly improved over those of the conventional materials.
  • composition range and process according to the present invention have enabled an extra high tensile steel having a yield strength of 1080 MPa or more and excellent in low-temperature toughness and stress corrosion cracking resistance at the welding-heat affected zone to be stably produced and supplied, so that it has become possible to significantly improve the reliability of containers and equipment used in a deep-sea environment.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
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Claims (2)

  1. Procédé pour produire un acier à ultra-haute résistance ayant une excellente résistance à la fissuration par corrosion sous contrainte, comprenant les étapes de: chauffage d'une brame comprenant, en pourcentages en masse, 0,04 à 0,09 % de C, 0,01 à 0,10 % de Si, 0,05 à 0,65 % de Mn, 8,0 à 11,0 % de Ni, 0,5 à 1,5 % de Mo, 0,2 à 1,5 % de Cr, 0,02 à 0,20 % de V et 0,01 à 0,08 % de Al, le complément consistant en fer et en impuretés inévitables, à une température située entre 1 000°C et 1 250°C, le laminage à chaud de la brame à une température du point Ar' ou supérieure, le refroidissement à l'air de la plaque laminée, le réchauffage de la plaque laminée à une vitesse de 120°C/min ou moins jusqu'à une région de température du (point Ac3 - 40°C) au (point Ac3 + 40°C), la trempe de la plaque réchauffée puis le revenu de la plaque trempée à une température du point Ac1 ou inférieure.
  2. Procédé pour produire un acier à ultra haute-résistance ayant une excellente résistance à la fissuration par corrosion sous contrainte, comprenant les étapes de : chauffage d'une brame comprenant, en pourcentages en masse, 0,04 à 0,09 % de C, 0,01 à 0,10 % de Si, 0,05 à 0,65 % de Mn, 8,0 à 11,0 % de Ni, 0,5 à 1,5 % de Mo, 0,2 à 1,5 % de Cr, 0,02 à 0,20 % de V et 0,01 à 0,08 % de Al et comprenant en outre au moins un élément choisi dans le groupe consistant en 0,2 à 1,5 % de Cu, 0,005 à 0,10 % de Nb et 0,005 à 0,03 % de Ti comme éléments améliorant la résistance et 0,0005 à 0,005 % de Ca et 0,0005 à 0,0100 % de MTR comme éléments ayant une capacité de réguler la forme des inclusions, le complément consistant en fer et en impuretés inévitables, à une température située entre 1 000°C et 1 250°C, le laminage à chaud de la brame à une température du point Ar' ou supérieure, le refroidissement à l'air de la plaque laminée, le réchauffage de la plaque laminée à une vitesse de 120°C/min ou moins jusqu'à une région de température du (point Ac3- 40°C) au (point Ac3 + 40°C), la trempe de la plaque réchauffée puis le revenu de la plaque trempée à une température du point Ac1 ou inférieure.
EP19930117410 1993-10-27 1993-10-27 Procédé pour la production d'acier à très haute résistance présentant une excellente résistance à la fissuration par corrosion sous contrainte Expired - Lifetime EP0651059B1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE1993626152 DE69326152T2 (de) 1993-10-27 1993-10-27 Verfahren zum Herstellen von hochfestem Stahl mit ausgezeichneter Beständigkeit gegen Spannungsrisskorrosion
EP19930117410 EP0651059B1 (fr) 1993-10-27 1993-10-27 Procédé pour la production d'acier à très haute résistance présentant une excellente résistance à la fissuration par corrosion sous contrainte

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EP19930117410 EP0651059B1 (fr) 1993-10-27 1993-10-27 Procédé pour la production d'acier à très haute résistance présentant une excellente résistance à la fissuration par corrosion sous contrainte

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EP0651059A1 EP0651059A1 (fr) 1995-05-03
EP0651059B1 true EP0651059B1 (fr) 1999-08-25

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JP6816467B2 (ja) * 2016-11-17 2021-01-20 日本製鉄株式会社 低温用ニッケル含有厚鋼板及びその製造方法
CN115896630B (zh) * 2022-12-05 2024-08-06 江苏省沙钢钢铁研究院有限公司 海洋工程用低温钢及其生产方法

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FR2307879A1 (fr) * 1975-04-18 1976-11-12 Siderurgie Fse Inst Rech Toles en acier au nickel pour utilisation a basse temperature
JPS61127815A (ja) * 1984-11-26 1986-06-16 Nippon Steel Corp 高アレスト性含Ｎｉ鋼の製造法
JPS61130462A (ja) * 1984-11-28 1986-06-18 Tech Res & Dev Inst Of Japan Def Agency 降伏応力１１０ｋｇｆ／ｍｍ↑２以上の耐応力腐蝕割れ性のすぐれた高靭性超高張力鋼
JPS63241114A (ja) * 1986-11-14 1988-10-06 Nippon Steel Corp 耐応力腐食割れ性の優れた高靭性高張力鋼の製造法
JPH01230713A (ja) * 1988-03-08 1989-09-14 Nippon Steel Corp 耐応力腐食割れ性の優れた高強度高靭性鋼の製造法
JPH03260012A (ja) * 1990-03-12 1991-11-20 Nippon Steel Corp 耐応力腐食割れ性の優れた高靭性超高張力鋼の製造法

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DE69326152D1 (de) 1999-09-30
DE69326152T2 (de) 2000-04-06

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