JP2823220B2 - Manufacturing method of steel plate with good weld joint toughness - Google Patents
Manufacturing method of steel plate with good weld joint toughnessInfo
- Publication number
- JP2823220B2 JP2823220B2 JP5414189A JP5414189A JP2823220B2 JP 2823220 B2 JP2823220 B2 JP 2823220B2 JP 5414189 A JP5414189 A JP 5414189A JP 5414189 A JP5414189 A JP 5414189A JP 2823220 B2 JP2823220 B2 JP 2823220B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- temperature
- less
- cooling
- steel sheet
- Prior art date
- 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
Links
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は溶接継手靭性の良い鋼板の製造法に関するも
のである。Description: TECHNICAL FIELD The present invention relates to a method for producing a steel sheet having good weld joint toughness.
（従来の技術） 鋼構造物を溶接により組立てる場合、溶接入熱量を増
加させることにより作業効率を向上させることが可能で
ある。しかしこのような大入熱溶接を行うと溶接熱影響
部の金属組織が著しく粗大化し、溶接継手靭性が劣化す
る問題が生ずる。(Prior Art) When assembling a steel structure by welding, it is possible to improve work efficiency by increasing the heat input of welding. However, when such large heat input welding is performed, the metallographic structure of the heat affected zone is significantly coarsened, causing a problem that the weld joint toughness is deteriorated.
これを解決する技術として、Ti添加により、溶接入熱
による最高到達温度における溶接熱影響部の金属組織の
粗大化を防止する技術およびTi析出物を利用して金属組
織を微細化する技術が報告されている。As technologies to solve this problem, a technology was added to prevent the coarsening of the microstructure of the weld heat affected zone at the highest temperature due to welding heat by adding Ti and a technology to refine the microstructure using Ti precipitates. Have been.
このような技術としては、例えば特開昭59−185760号
公報がある。しかしこのような技術では、添加したTiの
多くが鋼板中で粗大に析出した状態となっており、金属
組織の粗大化防止に有効に作用するものが少ないという
欠点があった。さらに過度の量のTi添加は母材材質の靭
性を劣化させるという欠点があった。As such a technique, there is, for example, JP-A-59-185760. However, such a technique has a disadvantage that much of the added Ti is in a state of being coarsely precipitated in the steel sheet, and there is little that effectively acts to prevent the coarsening of the metal structure. Further, there is a disadvantage that the addition of an excessive amount of Ti deteriorates the toughness of the base material.
（発明が解決しようとする課題） 本発明は鋼板中の固溶Ti量を確保し、Tiを最適な状態
に析出分散させる溶接継手靭性の良い鋼板の製造法を提
供するものである。(Problems to be Solved by the Invention) The present invention is to provide a method for producing a steel sheet having good toughness of a welded joint that secures the amount of solute Ti in a steel sheet and precipitates and disperses Ti in an optimum state.
（課題を解決するための手段） 本発明は上記のような従来法の欠点を有利に排除しう
る、微量のTi添加量でも溶接熱影響部靭性が良好な厚鋼
板の製造法であり、その要旨とする所は重量％でC:0.02
％〜0.25％、Si:0.05％〜0.6％、Mn:0.30％〜2.0％、A
l:0.005％〜0.10％、Ti:0.005〜0.10％、必要によりさ
らに、Nb≦0.05％、Cu≦1.0％、Ni≦2.5％、Cr≦1.0
％、Mo≦0.5％、Ｖ≦0.10％、Ｂ≦0.0025％の１種また
は２種以上を含有し、残部がFeおよび不可避的不純物か
らなる鋼を、鋳造後冷却することなくそのままAr3点以
上の温度域で熱間圧延し、圧延終了後常温まで放冷す
る。しかる後に当該鋼板を650℃以上850℃未満の温度で
熱処理することを特徴とする大入熱溶接用厚鋼板の製造
法である。(Means for Solving the Problems) The present invention is a method for producing a thick steel plate having good weld heat affected zone toughness even with a small amount of Ti added, which can advantageously eliminate the above-mentioned disadvantages of the conventional method. The abstract is C: 0.02 by weight%
% To 0.25%, Si: 0.05% to 0.6%, Mn: 0.30% to 2.0%, A
l: 0.005% to 0.10%, Ti: 0.005 to 0.10%, and if necessary, Nb ≦ 0.05%, Cu ≦ 1.0%, Ni ≦ 2.5%, Cr ≦ 1.0
%, Mo ≤ 0.5%, V ≤ 0.10%, B ≤ 0.0025%, steel containing Fe and unavoidable impurities with the balance being Ar 3 points or more without cooling after casting Hot rolling in the temperature range described above, and after the completion of rolling, it is allowed to cool to room temperature. Thereafter, the steel sheet is heat-treated at a temperature of 650 ° C. or more and less than 850 ° C., which is a method for producing a steel sheet for large heat input welding.
更に本発明においては、鋳造後冷却することなくその
ままAr3点以上の温度域で熱間圧延し、引続き２℃/s以
上60℃/s以下の冷却速度で500℃以下の温度まで冷却し
た鋼板を650℃以上850℃未満の温度で熱処理することが
できる。Further, in the present invention, the steel sheet is hot-rolled in a temperature range of 3 points or more of Ar without cooling after casting, and subsequently cooled to a temperature of 500 ° C or less at a cooling rate of 2 ° C / s or more and 60 ° C / s or less. Can be heat-treated at a temperature of 650 ° C. or more and less than 850 ° C.
以下本発明について詳細に説明する。 Hereinafter, the present invention will be described in detail.
溶接入熱による溶接熱影響部靭性の劣化を防止するた
めに、Tiを添加しその析出物で結晶粒の粗大化を防ぐこ
とが可能である。これはTi析出物が結晶粒界に存在して
粒成長を抑制することによりもたらされるが、Ti析出物
による粒成長抑制効果は、鋼中に存在するTi析出物の数
と寸法に存在する。In order to prevent deterioration of the toughness of the heat-affected zone due to heat input to the weld, it is possible to add Ti and prevent precipitates from coarsening crystal grains. This is caused by the fact that Ti precipitates are present at the grain boundaries to suppress grain growth, but the effect of Ti precipitates on grain growth exists in the number and size of Ti precipitates present in the steel.
よって従来の鋼板の製造法のように、鋼塊または鋼片
を鋳造後一端常温まで冷やした後に再加熱して熱間圧延
する方法では、添加したTiのうちの大半が粗大な析出物
として析出してしまい、溶接時の結晶粒の粒成長抑制に
は有効に作用しない。Therefore, as in the conventional steel sheet manufacturing method, in the method in which the ingot or billet is cooled once to room temperature after casting and then reheated and hot-rolled, most of the added Ti precipitates as coarse precipitates. Therefore, it does not effectively act to suppress the growth of crystal grains during welding.
しかるに、本発明者らは上記の限界を打破することを
可能とする新しい事実を発見し、それをもとに新たなる
大人熱溶接用鋼の製造法を導いた。However, the present inventors have discovered a new fact that makes it possible to overcome the above-mentioned limitations, and have led to a new method for producing a steel for adult heat welding based on the fact.
鋼塊または鋼片を鋳造後冷やすことなくそのまま熱間
圧延する方法では、添加したTiのうちの大半は鋼中に固
溶した状態で残存している、熱間圧延終了後引続き制御
冷却すれば固溶した状態で残存しているTiの割合いはさ
らに増加する。In the method of hot rolling without cooling after casting the ingot or slab, most of the added Ti remains in the steel in a solid solution state. The proportion of Ti remaining in a solid solution state further increases.
次にこの鋼板を熱処理することにより、固溶している
Tiは鋼中に析出し、その析出物の数と寸法は熱処理温度
により制御することが可能である。すなわち溶接時の結
晶粒の粒成長抑制に最も有効に作用する状態でTiを鋼中
に析出せしめることが可能となる。Next, this steel plate is heat-treated to form a solid solution.
Ti precipitates in the steel, and the number and size of the precipitates can be controlled by the heat treatment temperature. That is, Ti can be precipitated in steel in a state that most effectively acts to suppress the growth of crystal grains during welding.
このような新しい知見に基づき、鋼の化学成分、鋼板
の製造条件および圧延終了後の熱処理条件を詳細に調査
した結果、大人熱溶接用鋼の製造法を導いた。Based on these new findings, a detailed investigation of the chemical composition of the steel, the manufacturing conditions for the steel sheet, and the heat treatment conditions after the completion of rolling, led to a method for manufacturing a steel for adult thermal welding.
以下に製造方法の限定理由を詳細に説明する。 Hereinafter, the reasons for limiting the manufacturing method will be described in detail.
まず本発明における出発材の成分の限定理由について
述べる。First, the reasons for limiting the components of the starting material in the present invention will be described.
Ｃは、鋼を強化するのに有効な元素であり、0.02％未
満では十分な強度が得られない。一方その含有量が0.25
％を超えると、溶接性を劣化させる。C is an element effective for strengthening steel, and if it is less than 0.02%, sufficient strength cannot be obtained. On the other hand, the content is 0.25
%, The weldability deteriorates.
Siは脱酸元素として、また鋼の強化元素として有効で
あるが、0.05％未満の含有量ではその効果はない。一方
0.6％を超えると、鋼の表面性状を損なう。Although Si is effective as a deoxidizing element and as a strengthening element for steel, it is not effective at a content of less than 0.05%. on the other hand
If it exceeds 0.6%, the surface properties of the steel are impaired.
Mnは鋼の強化に有効な元素であり、0.30％未満では十
分な効果が得られない。一方、その含有量が2.0％を超
えると鋼の加工性を劣化させる。Mn is an effective element for strengthening steel, and if it is less than 0.30%, a sufficient effect cannot be obtained. On the other hand, if the content exceeds 2.0%, the workability of steel deteriorates.
Alは脱酸元素として添加される。0.005％未満の含有
量ではその効果がなく、0.1％を超えると、鋼の表面性
状を損なう。Al is added as a deoxidizing element. If the content is less than 0.005%, there is no effect, and if it exceeds 0.1%, the surface properties of the steel are impaired.
Tiは本発明で最も重要な役割を狙う元素であり、溶接
時の結晶粒の粒成長抑制に有効に作用するが、その含有
量が0.005％未満では十分な効果が得られない。0.1％を
超えると析出量が多くなり、かえって溶接熱影響部の靭
性を劣化させる。Ti is an element aimed at the most important role in the present invention, and effectively acts to suppress the growth of crystal grains during welding. However, if its content is less than 0.005%, a sufficient effect cannot be obtained. If it exceeds 0.1%, the amount of precipitation increases, and on the contrary, the toughness of the heat affected zone is deteriorated.
Nb,Tiはいずれも微量の添加で結晶粒の微細化と析出
硬化の面で有効に機能するから、溶接部の靭性を劣化さ
せない範囲で添加しても良い。この観点から、Nb,Tiと
もその添加量の上限を0.05％とする。Since Nb and Ti both function effectively in terms of crystal grain refinement and precipitation hardening when added in trace amounts, they may be added in a range that does not deteriorate the toughness of the welded portion. From this viewpoint, the upper limit of the addition amount of both Nb and Ti is set to 0.05%.
Cu,Ni,Cr,Moはいずれも鋼の焼入れ性を向上させる元
素である。本発明における場合、その添加により鋼の強
度を高めることができるが、過度の量の添加は鋼の溶接
性を損なうため、Cu≦1.0％、Ni≦2.5％、Cr≦1.0％、M
o≦0.5％に限定する。Cu, Ni, Cr, and Mo are all elements that improve the hardenability of steel. In the case of the present invention, the addition of the steel can increase the strength of the steel. However, an excessive amount of the steel impairs the weldability of the steel, so that Cu ≦ 1.0%, Ni ≦ 2.5%, Cr ≦ 1.0%, M
Limited to o ≦ 0.5%.
Ｖは、析出硬化により鋼の強度を高めるのに有効であ
るが、過度の添加は鋼の靭性を損なうため、その上限を
0.10％とする。V is effective in increasing the strength of the steel by precipitation hardening, but excessive addition impairs the toughness of the steel.
0.10%.
Ｂは鋼の焼入れ性を向上させる元素である。本発明に
おける場合、その添加により鋼の強度を高めることがで
きるが、過度の添加はＢの析出物を増加させて鋼の靭性
を損なうためその含有量の上限を0.0025％とする。B is an element that improves the hardenability of steel. In the case of the present invention, the strength of the steel can be increased by the addition thereof, but excessive addition increases the precipitates of B and impairs the toughness of the steel, so the upper limit of the content is made 0.0025%.
次に本発明におけるプロセス条件について述べる。 Next, the process conditions in the present invention will be described.
本発明はいかなる鋳造条件で鋳造された鋳片について
も有効であるので、特に鋳造条件を制限する必要はな
い。Since the present invention is effective for slabs cast under any casting conditions, there is no need to particularly limit the casting conditions.
鋳片を冷やすことなくそのまま熱間圧延を開始するこ
とが必要であるが、その熱間圧延温度をAr3点以上とし
たのは、それ以下まで温度が低下すればTiの析出が急速
に進行してしまうためである。It is necessary to start hot rolling as it is without cooling the slab, but the hot rolling temperature was set to the Ar 3 point or more because the precipitation of Ti progressed rapidly if the temperature dropped below that This is because
この条件が守られる限り、本発明はいかなる熱間圧延
条件で圧延された鋼板についても有効であるので、特に
圧延条件を制限する必要はない。圧延終了後は放冷して
も良いが、引続き２℃/s以上60℃/s以下の冷却速度で50
0℃以下の温度まで冷却することにより、固溶Ti量をよ
り多く確保することが可能である。As long as this condition is maintained, the present invention is effective for steel sheets rolled under any hot rolling conditions, so that it is not particularly necessary to limit the rolling conditions. After the end of rolling, it may be left to cool, but it will be continued at a cooling rate of 2 ° C / s or more and 60 ° C / s or less.
By cooling to a temperature of 0 ° C. or lower, it is possible to secure a larger amount of solid solution Ti.
冷却速度が２℃/s未満では析出を抑制するための冷却
の効果がなく、60℃/s超では鋼板が硬化して母材材質を
劣化させる。また冷却終了温度が500℃超ではその後の
放冷過程でTiが析出してしまうため500℃以下まで冷却
する。If the cooling rate is less than 2 ° C./s, there is no cooling effect for suppressing precipitation, and if it exceeds 60 ° C./s, the steel sheet hardens and deteriorates the base material. On the other hand, if the cooling end temperature is higher than 500 ° C., Ti is precipitated in the subsequent cooling step, so that the temperature is lowered to 500 ° C. or less.
このようにして製造された鋼板を650℃以上850℃未満
の温度で熱処理することにより、溶接時の結晶粒の粒成
長抑制に最も有効に作用する状態でTiを鋼中に液析せし
め得る。By subjecting the steel sheet thus manufactured to a heat treatment at a temperature of 650 ° C. or more and less than 850 ° C., Ti can be deposited in the steel in a state most effectively acting to suppress the growth of crystal grains during welding.
この熱処理の温度が650℃未満ではTiの析出が不十分
で溶接時の結晶粒の粒成長抑制ができない。一方、熱処
理の温度が850℃以上では、析出したTiが凝集してしま
いやはり溶接時の結晶粒の粒成長抑制ができない。If the temperature of this heat treatment is lower than 650 ° C., the precipitation of Ti is insufficient, so that the growth of crystal grains during welding cannot be suppressed. On the other hand, when the temperature of the heat treatment is 850 ° C. or more, the precipitated Ti is aggregated, so that the growth of crystal grains during welding cannot be suppressed.
（実 施 例） 第１表に示す成分の鋼について、第２表に示す本発明
方法および比較方法を適用した場合、第２表に示したよ
うな溶接熱影響部の靭性が得られ、明らかに本発明によ
り溶接熱影響部の靭性の向上がもたらされており、本発
明は有効である。(Examples) When the method of the present invention and the comparative method shown in Table 2 were applied to steels having the components shown in Table 1, the toughness of the weld heat affected zone as shown in Table 2 was obtained. According to the present invention, the toughness of the heat affected zone is improved by the present invention, and the present invention is effective.
（発明の効果） 本発明は鋼板中固溶Ti量を確保し、Tiを最適な状態に
分散析出させるので、溶接熱影響部の靭性の向上がもた
らされる。 (Effect of the Invention) The present invention secures the amount of solute Ti in a steel sheet and disperses and precipitates Ti in an optimum state, so that the toughness of the heat affected zone is improved.
フロントページの続き (72)発明者 土井 直己 千葉県君津市君津１ 新日本製鐵株式会 社君津製鐵所内 (56)参考文献 特開 昭61−170512（ＪＰ，Ａ) 特開 昭61−221332（ＪＰ，Ａ) 特開 昭63−203720（ＪＰ，Ａ) 特開 平２−19423（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) C21D 8/02 C21D 9/46 - 9/52 B21B 1/00 - 3/02Continuation of the front page (72) Inventor Naoki Doi 1 Kimitsu, Kimitsu City, Chiba Prefecture Inside the Nippon Steel Corporation Kimitsu Works (56) References JP-A-61-170512 (JP, A) JP-A-61-221332 (JP, A) JP-A-63-203720 (JP, A) JP-A-2-19423 (JP, A) (58) Fields investigated (Int. Cl. 6 , DB name) C21D 8/02 C21D 9 / 46-9/52 B21B 1/00-3/02
Claims (4)
却することなくそのままAr3点以上の温度域で熱間圧延
し、圧延終了後常温まで放冷し、しかる後に該鋼板を65
0℃以上の850℃未満の温度に再び加熱することを特徴と
する溶接継手靭性の良い鋼板の製造法。(1) By weight%, C: 0.02 to 0.25%, Si: 0.05 to 0.6%, Mn: 0.30 to 2.0%, Al: 0.005 to 0.10%, Ti: 0.005 to 0.10%, the balance being Fe and inevitable The steel composed of impurities is hot-rolled as it is without cooling after casting in a temperature range of 3 points or more of Ar, allowed to cool to room temperature after the completion of rolling, and then cooled to 65 ° C.
A method for producing a steel plate having good toughness of a weld joint, wherein the steel sheet is heated again to a temperature of 0 ° C or more and less than 850 ° C.
となくそのままAr3点以上の温度域で熱間圧延し、引続
き２℃/s以上60℃/s以下の冷却速度で500℃以下の温度
まで冷却した鋼板を、650℃以上850℃未満の温度で熱処
理することを特徴とする特許請求の範囲第１項記載の溶
接継手靭性の良い鋼板の製造法。2. The steel of the above-mentioned composition is hot-rolled as it is without cooling after casting in a temperature range of not less than 3 points of Ar and subsequently at 500 ° C. at a cooling rate of 2 ° C./s or more and 60 ° C./s or less. 2. The method according to claim 1, wherein the steel sheet cooled to the following temperature is heat-treated at a temperature of 650 ° C. or more and less than 850 ° C.
的不純物からなる鋼を、鋳造後冷却することなくそのま
まAr3点以上の温度域で熱間圧延し、圧延終了後常温ま
で放冷し、しかる後に該鋼板を650℃以上850℃未満の温
度で熱処理することを特徴とする溶接継手靭性の良い鋼
板の製造法。C .: 0.02 to 0.25% by weight, Si: 0.05 to 0.6%, Mn: 0.30 to 2.0%, Al: 0.005 to 0.10%, Ti: 0.005 to 0.10% by weight, and further Nb. ≦ 0.05%, Cu ≦ 1.0%, Ni ≦ 2.5%. A steel containing one or more of Cr ≦ 1.0%, Mo ≦ 0.5%, V ≦ 0.10%, B ≦ 0.0025%, with the balance being Fe and unavoidable impurities, without cooling after casting Ar hot rolling in the temperature range of three or more points, allowed to cool to room temperature after the end of the rolling, and then the steel sheet is heat treated at a temperature of 650 ° C or more and less than 850 ° C. Manufacturing method.
となくそのままAr3点以上の温度域で熱間圧延し、引続
き２℃/s以上60℃/s以下の冷却速度で500℃以下の温度
まで冷却した鋼板を、650℃以上850℃未満の温度で熱処
理することを特徴とする特許請求の範囲第３項記載の溶
接継手靭性の良い鋼板の製造法。4. The steel of the above-mentioned composition is hot-rolled in a temperature range of not less than 3 points of Ar without cooling after casting, and subsequently cooled at a cooling rate of 2 ° C./s to 60 ° C./s at 500 ° C. 4. The method according to claim 3, wherein the steel sheet cooled to the following temperature is heat-treated at a temperature of 650 ° C. or more and less than 850 ° C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5414189A JP2823220B2 (en) | 1989-03-07 | 1989-03-07 | Manufacturing method of steel plate with good weld joint toughness |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5414189A JP2823220B2 (en) | 1989-03-07 | 1989-03-07 | Manufacturing method of steel plate with good weld joint toughness |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02232315A JPH02232315A (en) | 1990-09-14 |
| JP2823220B2 true JP2823220B2 (en) | 1998-11-11 |
Family
ID=12962285
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5414189A Expired - Lifetime JP2823220B2 (en) | 1989-03-07 | 1989-03-07 | Manufacturing method of steel plate with good weld joint toughness |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2823220B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102676945B (en) * | 2012-04-25 | 2015-01-07 | 舞阳钢铁有限责任公司 | Easily-weldable tempered high-strength ductile steel plate used in hydroelectric projects and production method thereof |
| CN104294174B (en) * | 2014-11-07 | 2016-05-11 | 江苏天舜金属材料集团有限公司 | A kind of Large Heat Input Welding high-strength hot-rolled steel bar and production technology thereof |
-
1989
- 1989-03-07 JP JP5414189A patent/JP2823220B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02232315A (en) | 1990-09-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3015924B2 (en) | Manufacturing method for tough steel | |
| JPH0551633A (en) | Production of high si-containing austenitic stainless steel | |
| JP2823220B2 (en) | Manufacturing method of steel plate with good weld joint toughness | |
| JPH0741854A (en) | Production of ferrite single phase stainless hot rolled steel sheet excellent in toughness | |
| JP2828303B2 (en) | Manufacturing method of tough steel plate | |
| JPH0629480B2 (en) | Hot-rolled high-strength steel sheet excellent in strength, ductility, toughness, and fatigue characteristics, and method for producing the same | |
| JP2875572B2 (en) | Soaking process in the production of tough steel | |
| JP3635803B2 (en) | Method for producing high-tensile steel with excellent toughness | |
| JPS642647B2 (en) | ||
| JP3212344B2 (en) | Manufacturing method of structural steel plate for welding with excellent toughness at low temperature | |
| JP3067892B2 (en) | Manufacturing method of ferritic stainless steel sheet with excellent surface properties and deep drawability | |
| JP2706159B2 (en) | Method for producing low yield ratio high strength steel with good weldability | |
| JP3848397B2 (en) | Manufacturing method of high-efficiency and highly uniform tough steel plate | |
| JP2633744B2 (en) | Manufacturing method of thick steel plate with fine grain size | |
| JP2633743B2 (en) | Manufacturing method of thick steel plate with fine grain size | |
| JP2003129133A (en) | Method for manufacturing thick steel plate with high strength and high toughness | |
| JPH0774380B2 (en) | Manufacturing method of high strength steel | |
| JP2510921B2 (en) | Method for controlling hot rolling structure of steel | |
| JP2627114B2 (en) | Hot rolling method for steel with good toughness | |
| JPH06158233A (en) | Production of ferritic stainless steel thin slab excellent in toughness and ferritic stainless steel strip by the same thin slab | |
| JP2915691B2 (en) | High ductility austenitic-ferrite dual phase heat resistant steel and method for producing the same | |
| JP3107695B2 (en) | Method for producing shaped steel having flange with excellent strength, toughness and weldability | |
| JP3348793B2 (en) | Manufacturing method of refractory steel for building structures | |
| JPH0613733B2 (en) | High toughness steel plate manufacturing method | |
| JPH08337815A (en) | Production of chromium-molybdenum steel excellent in strength and toughness |