JPH05112832A - Manufacture of low yield ratio-high tensile strength-hot rolled steel sheet excellent in corrosion resistance - Google Patents
Manufacture of low yield ratio-high tensile strength-hot rolled steel sheet excellent in corrosion resistanceInfo
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- JPH05112832A JPH05112832A JP29776491A JP29776491A JPH05112832A JP H05112832 A JPH05112832 A JP H05112832A JP 29776491 A JP29776491 A JP 29776491A JP 29776491 A JP29776491 A JP 29776491A JP H05112832 A JPH05112832 A JP H05112832A
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は，フエライトとマルテン
サイトからなる複合組織を有する低降伏比，高延性の耐
食性に優れた高張力熱延鋼板の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-strength hot-rolled steel sheet having a composite structure composed of ferrite and martensite, having a low yield ratio, high ductility and excellent corrosion resistance.
【０００２】[0002]
【従来の技術】自動車産業では車体の防錆化と軽量化を
目的として耐食性と加工性に優れた高張力鋼板が要求さ
れている。一般に鋼は降伏点および引張強さ等の強度が
上昇するに従って伸びや曲げ等の延性が低下する。した
がって，固溶強化，析出強化等を利用して強度を高めた
高張力鋼板では加工用途には不充分となる。2. Description of the Related Art In the automobile industry, high-strength steel sheets having excellent corrosion resistance and workability are required for the purpose of preventing rust and weight of the vehicle body. Generally, steel has lower ductility such as elongation and bending as the strength such as yield point and tensile strength increases. Therefore, high-strength steel sheets, which have been strengthened by utilizing solid solution strengthening, precipitation strengthening, etc., are insufficient for processing applications.
【０００３】このような背景から開発された高張力鋼板
として複合組織高張力鋼板がある。例えば特開平2-1758
17号公報には, Ｃ-高Ｍn鋼やＣ-Ｓi-高Ｍn鋼の熱延条件
と焼鈍条件を規制することによってフエライト＋マルテ
ンサイトの複合組織とすると共に強度と伸びを向上させ
る複合組織熱延高張力鋼板の製造法が記載されている。As a high-strength steel plate developed from such a background, there is a composite structure high-strength steel plate. For example, Japanese Patent Laid-Open No. 2-1758
No. 17 discloses a composite microstructure heat that improves the strength and elongation of a C-high Mn steel or C-Si-high Mn steel by controlling the hot rolling conditions and annealing conditions to form a composite structure of ferrite and martensite. A method for manufacturing a rolled high strength steel sheet is described.
【０００４】[0004]
【発明が解決しようとする課題】複合組織鋼板の製造技
術は, 特に自動車用高張力鋼板向けにその強度と伸びを
同時に付与するのに開発され，自動車用鋼板の薄肉化す
なわち軽量化を達成しようとするものであるが，前記公
報に記載の熱延技術では巻取り温度を非常に低温の300
℃以下にする必要がある。[Problems to be Solved by the Invention] The manufacturing technique of a composite microstructure steel sheet has been developed to impart strength and elongation at the same time especially for high-strength steel sheets for automobiles, and to achieve thinning, that is, weight reduction of automobile steel sheets. However, in the hot rolling technique described in the above publication, the coiling temperature is set to a very low temperature of 300
It must be below ℃.
【０００５】また，これら鋼板の採用によって強度面か
らは鋼板の板厚を薄くすることは可能であるが，板厚を
薄くすると腐食により鋼板の孔あき腐食の問題が顕在化
してくる。Further, although it is possible to reduce the plate thickness of the steel plate from the viewpoint of strength by adopting these steel plates, the problem of perforation corrosion of the steel plate becomes apparent due to corrosion when the plate thickness is reduced.
【０００６】本発明は，上述の事情に鑑み, 複合組織鋼
板の耐食性を改善し，耐食性と加工性を同時に満足しう
る低降伏比高張力熱延板を得ることを目的とする。In view of the above-mentioned circumstances, it is an object of the present invention to improve the corrosion resistance of a steel sheet having a composite structure and to obtain a low yield ratio high tensile hot-rolled sheet which can satisfy both the corrosion resistance and the workability at the same time.
【０００７】[0007]
【課題を解決するための手段】本発明によれば，重量％
で, Ｃ：0.02〜0.25％, Ｓi：2.0％以下, Ｍn：1.6〜3.
5％, Ｐ：0.03〜0.20％, Ｓ：0.02％以下, Ｃu：0.05〜
2.0％, sol.Ａl：0.005〜0.100％, Ｎ：0.008％以下を
含有し, 場合によってはさらに，Ｔi：0.005〜0.06％ま
たはＮb：0.005〜0.06％の少なくとも一種以上，および
／またはＮi：2.0％以下, Ｍo：3.0％以下またはＣr：
3.0％以下の少なくとも一種以上を含有し, 場合によっ
てはさらにＢ：0.0003〜0.005％を含有し, 残部が鉄お
よび不可避的不純物よりなる鋼のスラブを熱間圧延し,
酸洗後, その熱延コイルを連続焼鈍ラインで720〜950℃
の温度で焼鈍することからなる耐食性に優れた低降伏比
高張力熱延板の製造方法を提供する。According to the present invention, the weight percent is
C: 0.02 to 0.25%, Si: 2.0% or less, Mn: 1.6 to 3.
5%, P: 0.03 to 0.20%, S: 0.02% or less, Cu: 0.05 to
2.0%, sol.Al: 0.005 to 0.100%, N: 0.008% or less, and if necessary, at least one or more of Ti: 0.005 to 0.06% or Nb: 0.005 to 0.06%, and / or Ni: 2.0 % Or less, Mo: 3.0% or less or Cr:
A steel slab containing 3.0% or less of at least one type and, if necessary, B: 0.0003 to 0.005% and the balance of iron and unavoidable impurities is hot-rolled,
After pickling, the hot-rolled coil was continuously annealed at 720-950 ℃.
Provided is a method for producing a low-yield ratio, high-strength hot-rolled sheet excellent in corrosion resistance, which comprises annealing at a temperature of.
【０００８】[0008]
【作用】低炭素鋼に焼入れ性を向上させるＭn,Ｎi,Ｃr
等の合金元素を添加して熱延焼鈍状態でフエライト＋マ
ルテンサイトの複合組織とすることができ，さらに, 微
量のＴi,Ｎbを含有させると複合組織鋼の欠点である孔
拡げ性を改善できる。また適量のＣu,Ｐの含有はこの鋼
の耐食性を向上させる。高強度化と耐食性を向上させる
にはＳi,Ｍnの添加およびＮi,Ｍo,Ｃrの添加が有効であ
る。これらの複合的な作用によって加工性と耐食性に優
れた自動車用高張力熱延鋼板を得ることができる。[Operation] Mn, Ni, Cr for improving hardenability in low carbon steel
It is possible to form a composite structure of ferrite + martensite in the hot-rolled and annealed state by adding alloy elements such as Fe. Further, if a small amount of Ti, Nb is contained, the hole expandability, which is a drawback of the composite structure steel, can be improved. .. Also, the inclusion of an appropriate amount of Cu, P improves the corrosion resistance of this steel. Addition of Si and Mn and additions of Ni, Mo and Cr are effective for increasing strength and improving corrosion resistance. Due to these combined actions, a high-strength hot-rolled steel sheet for automobiles having excellent workability and corrosion resistance can be obtained.
【０００９】本発明法に従う鋼板の各種成分の作用およ
びその含有量範囲の限定理由は次のとおりである。Ｃ
は, フエライトとマルテンサイトからなる複合組織を得
ること，また強度を向上させるに有効な元素である。目
的とする複合組織を得るために，Ｃは0.02％以上必要で
あるが，0.25％を超えると延性および溶接性が悪くな
る。このため下限を0.02％, 上限を0.25％とした。The actions of various components of the steel sheet according to the method of the present invention and the reasons for limiting the content range thereof are as follows. C
Is an element effective in obtaining a composite structure composed of ferrite and martensite and improving the strength. In order to obtain the target composite structure, C must be 0.02% or more, but if it exceeds 0.25%, ductility and weldability deteriorate. Therefore, the lower limit was 0.02% and the upper limit was 0.25%.
【００１０】Ｓiは，加工性を損なわず鋼の強度を向上
させるに好ましい元素であり，また焼鈍時に高温のオー
ステナイトからの冷却過程においてフエライトの生成が
促進されことを通じて複合組織が得られる効果がある
が，Ｓiが約2.0％を超えるとこの効果が飽和するととも
に硬質となり延性が劣化する。このため上限を2.0％と
した。Si is a preferable element for improving the strength of steel without impairing workability, and it has an effect that a composite structure can be obtained by promoting the formation of ferrite in the cooling process from austenite at high temperature during annealing. However, when Si exceeds about 2.0%, this effect saturates and becomes hard and the ductility deteriorates. Therefore, the upper limit was set to 2.0%.
【００１１】Ｍnは，鋼の焼入れ性を向上させ，複合組
織を得るために有効に作用する元素である。Ｍn量が1.6
％未満では低降伏比特性を有する複合組織が得られず，
一方, 3.5％を超えると加工性および溶接性を低下させ
る。このため下限を1.6％,上限を3.5％とした。Mn is an element that acts effectively to improve the hardenability of steel and obtain a composite structure. Mn amount is 1.6
%, A composite structure having a low yield ratio characteristic cannot be obtained,
On the other hand, if it exceeds 3.5%, the workability and weldability deteriorate. Therefore, the lower limit is 1.6% and the upper limit is 3.5%.
【００１２】ＰおよびＣuは，本発明における特徴的な
元素であり,これらの元素の複合添加によって耐食性が
著しく改善される。耐食性の改善のためにＰは0.03％以
上,Ｃuは0.05％以上必要である。一方Ｐは0.20％を, Ｃ
uは2.0％を超えて添加しても耐食性改善効果が飽和し，
延性が劣化する。このためＰは0.03〜0.2％, Ｃuは0.05
〜2.0％とする。P and Cu are characteristic elements in the present invention, and the corrosion resistance is remarkably improved by the combined addition of these elements. To improve the corrosion resistance, P must be 0.03% or more and Cu must be 0.05% or more. On the other hand, P is 0.20%, C
Even if u exceeds 2.0%, the effect of improving corrosion resistance saturates,
Ductility deteriorates. Therefore, P is 0.03 to 0.2% and Cu is 0.05.
~ 2.0%
【００１３】Ｓは，鋼にとって本質的に有害な元素であ
り, 少ないほど望ましいが0.02％までは許容できるので
0.02％以下とする。S is an element that is essentially harmful to steel. The smaller the amount, the more desirable, but 0.02% is acceptable.
0.02% or less.
【００１４】Ａlは，脱酸剤としての役割を果たすため
に0.005％以上必要であるが，0.10％を超えるとＡl2Ｏ3
などの介在物が増加し，加工性および表面品質を劣化さ
せるので，下限を0.005％, 上限を0.10％とした。Al needs to be 0.005% or more in order to function as a deoxidizer, but if it exceeds 0.10%, Al 2 O 3
Increasing inclusions such as these deteriorate workability and surface quality, so the lower limit was made 0.005% and the upper limit was made 0.10%.
【００１５】Ｎは，本発明鋼の場合には本質的に有害な
元素であり少ないほど望ましいが,0.008％までは許容で
きるので0.008％以下とする。In the case of the steel of the present invention, N is an essentially harmful element, and the smaller the amount, the better. However, N is 0.008% or less, so 0.008% or less is acceptable.
【００１６】また，本発明においては，2.0％までのＮ
i, 3.0％までのＭo, 3.0％までのＣrの一種もしくは二
種以上含有させると鋼板の強度と耐食性を改善すること
ができる。Further, in the present invention, N up to 2.0%
If one or more of i, Mo up to 3.0% and Cr up to 3.0% are contained, the strength and corrosion resistance of the steel sheet can be improved.
【００１７】Ｎiは，Ｃuによる熱間脆性の防止と耐食性
の改善に有効に作用するが，2.0％を超えるとその効果
は飽和するとともに製造コストが高価となる。このため
上限を2.0％とする。Ni effectively acts to prevent hot brittleness and improve corrosion resistance due to Cu, but if it exceeds 2.0%, the effect is saturated and the manufacturing cost becomes expensive. Therefore, the upper limit is 2.0%.
【００１８】Ｍoは，鋼板の強度上昇と耐食性の改善に
有効に作用するが，3.0％を超えるとその効果は飽和す
るとともに製造コストが高価となるので上限を3.0％と
する。Mo effectively acts to increase the strength of the steel sheet and improve the corrosion resistance, but if it exceeds 3.0%, the effect is saturated and the manufacturing cost becomes high, so the upper limit is made 3.0%.
【００１９】Ｃrは，耐孔あき腐食性の改善に有効に作
用するが３％を超えると製造コスト高となるので，上限
を3.0％とする。Cr is effective in improving the resistance to pitting corrosion, but if it exceeds 3%, the manufacturing cost becomes high, so the upper limit is made 3.0%.
【００２０】Ｂは，焼入れ性を向上させるとともに粒界
を強化する元素である。このような効果を得るには0.00
03％以上の添加が必要であるが,0.005％を超えて添加し
てもその効果は飽和する。このため下限を0.0003％, 上
限を0.005％とする。B is an element that improves hardenability and strengthens grain boundaries. 0.00 for this effect
It is necessary to add more than 03%, but even if added over 0.005%, the effect is saturated. Therefore, the lower limit is 0.0003% and the upper limit is 0.005%.
【００２１】ＴiおよびＮbは金属組織を微細化し，延性
を向上させまた複合組織鋼の欠点である孔拡げ性の改善
に効果がある。このような効果を得るには0.005％以上
の添加が必要であるが，0.06％を超えて添加すると微細
なＴiＣやＮbＣの析出量が多くなり延性を劣化させる。
このためいずれの元素も下限を0.005％, 上限を0.06％
とする。Ti and Nb have the effects of refining the metal structure, improving the ductility, and improving the hole expandability, which is a drawback of composite structure steel. To obtain such an effect, 0.005% or more must be added, but if added over 0.06%, the fine TiC and NbC precipitation amounts increase and ductility deteriorates.
Therefore, for all elements, the lower limit is 0.005% and the upper limit is 0.06%.
And
【００２２】本発明においては, かかる成分を含有する
鋼のスラブを熱間圧延し，酸洗後，その熱延コイルを連
続焼鈍ラインで720℃以上950℃以下の温度で焼鈍し，必
要に応じて軽度のスキンパスを行って目標板厚の製品薄
鋼板を得る。熱間圧延での仕上げ温度はＡr3変態点以上
とするのが加工性向上のうえから好ましく, 巻取り温度
は500〜750℃の範囲内で行えばよい。In the present invention, a steel slab containing such components is hot-rolled, pickled, and then the hot-rolled coil is annealed in a continuous annealing line at a temperature of 720 ° C. or higher and 950 ° C. or lower, and if necessary, A light skin pass is performed to obtain the product thin steel plate of the target thickness. It is preferable that the finishing temperature in hot rolling is not less than the Ar 3 transformation point in order to improve workability, and the winding temperature may be in the range of 500 to 750 ° C.
【００２３】連続焼鈍ラインにおける焼鈍温度の下限を
720℃とするのは, 複合組織を得るために必要な最低温
度として720℃は要するからである。上限を950℃とする
のはこの温度を超えても加工性の向上効果が飽和すると
共に連続焼鈍ラインにおいて表面疵が発生し易くなるた
めである。The lower limit of the annealing temperature in the continuous annealing line is set to
The reason for setting the temperature to 720 ° C is that 720 ° C is required as the minimum temperature required to obtain a composite structure. The upper limit of 950 ° C. is that the effect of improving the workability is saturated and the surface flaw is likely to occur in the continuous annealing line even if this temperature is exceeded.
【００２４】連続焼鈍後の冷却過程での冷却速度が遅い
と複合組織が得にくく，そのため焼入れ性向上元素の添
加を多く必要とする。このため冷却速度は速い方が望ま
しいが，焼鈍温度から約450℃までの平均冷却速度が３
℃/sec以上であれば問題はない。If the cooling rate in the cooling process after continuous annealing is slow, it is difficult to obtain a composite structure, and therefore it is necessary to add many hardenability improving elements. For this reason, it is desirable that the cooling rate be fast, but the average cooling rate from the annealing temperature to approximately 450 ° C is 3
There is no problem if it is ℃ / sec or more.
【００２５】[0025]
【実施例】表１に示す化学成分値の鋼を，表２に示す条
件のもとで，熱間圧延によって板厚2.5mmの熱延板とし
たうえ，酸洗後，連続焼鈍ラインにて焼鈍し, その後伸
び率0.3％のスキンパス圧延を行った。得られた熱延焼
鈍板の特性を調べた。その結果を表２に示した。[Examples] Steels having the chemical composition values shown in Table 1 were hot-rolled under the conditions shown in Table 2 into hot-rolled sheets having a thickness of 2.5 mm, pickled, and then subjected to a continuous annealing line. It was annealed and then skin pass rolled with an elongation of 0.3%. The characteristics of the obtained hot rolled annealed sheet were examined. The results are shown in Table 2.
【００２６】なお，引張特性はJIS Z 2201の５号試験片
を用いた。孔拡げ試験は150×150mmの試験片の中心部に
直径10mmの打抜き孔をあけ，その後, 直径50mmの球頭ポ
ンチにて孔拡げ試験を行った。耐食試験は70×150mmの
試験片を切りだし, 複合腐食試験を行った。複合腐食試
験はJIS Z 2371の塩水噴霧試験に準じ, 塩水濃度が５％
の塩水噴霧試験を２時間→60℃の熱風乾燥を４時間→湿
潤試験を２時間からなる合計８時間の処理を１サイクル
として，240サイクル後の腐食による最大侵食深さを測
定することによって評価した。The tensile properties used were JIS Z 2201 No. 5 test pieces. For the hole expansion test, a punch hole with a diameter of 10 mm was made in the center of a 150 × 150 mm test piece, and then a hole expansion test was performed with a ball head punch with a diameter of 50 mm. For the corrosion resistance test, a 70 × 150 mm test piece was cut out and a complex corrosion test was performed. The complex corrosion test conforms to the JIS Z 2371 salt spray test, and the salt water concentration is 5%.
The salt spray test of 2 hours → hot air drying at 60 ° C for 4 hours → wet test for 2 hours was treated as one cycle for a total of 8 hours, and the maximum corrosion depth due to corrosion after 240 cycles was measured. did.
【００２７】[0027]
【表１】 [Table 1]
【００２８】[0028]
【表２】 [Table 2]
【００２９】表２の結果に見られるように，Ｍn,Ｐが本
発明で規定する量より低く且つＣu無添加の鋼を用いて
製造したNo.1の比較例の鋼板は，降伏比 (ＹＲ）が高く
て低降伏比の複合組織鋼板が得られていないし，伸び
（Ｅｌ）および孔拡げ率（λ）も低く且つ耐食性が劣
る。同じくＰが低く且つＣu無添加のNo.2の比較例（Ｍn
がNo.1より増量している) では降伏比（ＹＲ）が低く，
伸び（Ｅｌ）も良好な複合組織鋼となっているが，耐食
性が劣る。そして孔拡げ率（λ）も低い。As can be seen from the results in Table 2, the steel sheet of Comparative Example No. 1 manufactured by using the steel in which Mn and P were lower than the amounts specified in the present invention and in which no Cu was added had a yield ratio (YR ) Is not obtained, a steel sheet with a high yield ratio and a low yield ratio has not been obtained, the elongation (El) and the hole expansion ratio (λ) are low, and the corrosion resistance is poor. Similarly, a comparative example of No. 2 with a low P and no Cu added (Mn
Is higher than No. 1), the yield ratio (YR) is low,
The composite steel has a good elongation (El), but has poor corrosion resistance. The hole expansion ratio (λ) is also low.
【００３０】これに対して, 本発明法に従うNo.3〜14の
鋼板は降伏比（ＹＲ）が低く，伸び（Ｅｌ）も良好な複
合組織鋼が得られており，強度が高いわりに孔拡げ率
（λ）も高く, しかも耐食性に優れている。On the other hand, steel sheets Nos. 3 to 14 according to the method of the present invention have a composite structure steel with a low yield ratio (YR) and a good elongation (El). The rate (λ) is also high and the corrosion resistance is excellent.
【００３１】[0031]
【発明の効果】以上のように本発明によれば，低降伏
比, 高延性および良好な孔拡げ性を維持し, しかも耐食
性に優れた複合組織の高張力熱延鋼板を製造することが
できる。この鋼板は自動車の車体特に足回り部品の軽量
化と腐食防止に大きく寄与することができる。As described above, according to the present invention, it is possible to manufacture a high tensile strength hot rolled steel sheet having a composite structure which maintains a low yield ratio, a high ductility and a good hole expandability and is excellent in corrosion resistance. .. This steel sheet can greatly contribute to the weight reduction and corrosion prevention of the body of an automobile, especially the underbody parts.
フロントページの続き (51)Int.Cl.5 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｃ２２Ｃ 38/50 38/54 Continuation of the front page (51) Int.Cl. 5 Identification code Office reference number FI technical display location C22C 38/50 38/54
Claims (3)
％以下, Ｍn：1.6〜3.5％, Ｐ：0.03〜0.20％, Ｓ：0.0
2％以下, Ｃu：0.05〜2.0％, sol.Ａl：0.005〜0.100
％, Ｎ：0.008％以下を含有し，残部が鉄および不可避
的不純物よりなる鋼のスラブを熱間圧延し, 酸洗後, そ
の熱延コイルを連続焼鈍ラインで720〜950℃の温度で焼
鈍することからなる耐食性に優れた低降伏比高張力熱延
鋼板の製造方法。1. By weight%, C: 0.02-0.25%, Si: 2.0
% Or less, Mn: 1.6 to 3.5%, P: 0.03 to 0.20%, S: 0.0
2% or less, Cu: 0.05 to 2.0%, sol.Al: 0.005 to 0.100
%, N: 0.008% or less, the balance is steel and the balance is steel and unavoidable impurities, hot-rolled the steel slab, and after pickling, the hot-rolled coil is annealed at a temperature of 720-950 ℃ in a continuous annealing line. A method for producing a high yield hot rolled steel sheet having a low yield ratio and excellent corrosion resistance.
％以下, Ｍn：1.6〜3.5％, Ｐ：0.03〜0.20％, Ｓ：0.0
2％以下, Ｃu：0.05〜2.0％, sol.Ａl：0.005〜0.100
％, Ｎ：0.008％以下を含有したうえ，さらに，Ｔi：0.
005〜0.06％またはＮb：0.005〜0.06％の少なくとも一
種以上，および／またはＮi：2.0％以下, Ｍo：3.0％以
下またはＣr：3.0％以下の少なくとも一種以上を含有
し,残部が鉄および不可避的不純物よりなる鋼のスラブ
を熱間圧延し, 酸洗後, その熱延コイルを連続焼鈍ライ
ンで720〜950℃の温度で焼鈍することからなる耐食性に
優れた低降伏比高張力熱延鋼板の製造方法。2. By weight%, C: 0.02 to 0.25%, Si: 2.0
% Or less, Mn: 1.6 to 3.5%, P: 0.03 to 0.20%, S: 0.0
2% or less, Cu: 0.05 to 2.0%, sol.Al: 0.005 to 0.100
%, N: 0.008% or less, and Ti: 0.
005 to 0.06% or Nb: 0.005 to 0.06% at least one or more, and / or Ni: 2.0% or less, Mo: 3.0% or less or Cr: 3.0% or less at least one or more, and the balance is iron and unavoidable A steel slab made of impurities is hot-rolled, pickled, and then the hot-rolled coil is annealed at a temperature of 720 to 950 ° C in a continuous annealing line to produce a low yield ratio high-strength hot-rolled steel sheet with excellent corrosion resistance. Production method.
％以下, Ｍn：1.6〜3.5％, Ｐ：0.03〜0.20％, Ｓ：0.0
2％以下, Ｃu：0.05〜2.0％, sol.Ａl：0.005〜0.100
％, Ｎ：0.008％以下，Ｂ：0.0003〜0.005％を含有した
うえ，さらに，Ｔi：0.005〜0.06％またはＮb：0.005〜
0.06％の少なくとも一種以上，および／またはＮi：2.0
％以下, Ｍo：3.0％以下またはＣr：3.0％以下の少なく
とも一種以上を含有し, 残部が鉄および不可避的不純物
よりなる鋼のスラブを熱間圧延し, 酸洗後, その熱延コ
イルを連続焼鈍ラインで720〜950℃の温度で焼鈍するこ
とからなる耐食性に優れた低降伏比高張力熱延鋼板の製
造方法。3. By weight%, C: 0.02-0.25%, Si: 2.0
% Or less, Mn: 1.6 to 3.5%, P: 0.03 to 0.20%, S: 0.0
2% or less, Cu: 0.05 to 2.0%, sol.Al: 0.005 to 0.100
%, N: 0.008% or less, B: 0.0003 to 0.005%, Ti: 0.005 to 0.06% or Nb: 0.005 to
0.06% of at least one and / or Ni: 2.0
% Or less, Mo: 3.0% or less or Cr: 3.0% or less, at least one of which is steel and the balance is iron and unavoidable impurities, hot-rolled, and after pickling, the hot-rolled coil is continuous. A method for producing a high yield hot rolled steel sheet with a low yield ratio and excellent corrosion resistance, which comprises annealing at a temperature of 720 to 950 ° C in an annealing line.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29776491A JP3144572B2 (en) | 1991-10-18 | 1991-10-18 | Manufacturing method of low yield ratio high tensile strength hot rolled steel sheet with excellent corrosion resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29776491A JP3144572B2 (en) | 1991-10-18 | 1991-10-18 | Manufacturing method of low yield ratio high tensile strength hot rolled steel sheet with excellent corrosion resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05112832A true JPH05112832A (en) | 1993-05-07 |
| JP3144572B2 JP3144572B2 (en) | 2001-03-12 |
Family
ID=17850874
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP29776491A Expired - Fee Related JP3144572B2 (en) | 1991-10-18 | 1991-10-18 | Manufacturing method of low yield ratio high tensile strength hot rolled steel sheet with excellent corrosion resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3144572B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012002565A1 (en) | 2010-06-29 | 2012-01-05 | Ｊｆｅスチール株式会社 | High-strength hot-dip galvanized steel sheet with excellent processability and process for producing same |
| WO2012002566A1 (en) | 2010-06-29 | 2012-01-05 | Ｊｆｅスチール株式会社 | High-strength steel sheet with excellent processability and process for producing same |
-
1991
- 1991-10-18 JP JP29776491A patent/JP3144572B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012002565A1 (en) | 2010-06-29 | 2012-01-05 | Ｊｆｅスチール株式会社 | High-strength hot-dip galvanized steel sheet with excellent processability and process for producing same |
| WO2012002566A1 (en) | 2010-06-29 | 2012-01-05 | Ｊｆｅスチール株式会社 | High-strength steel sheet with excellent processability and process for producing same |
| US9073292B2 (en) | 2010-06-29 | 2015-07-07 | Jfe Steel Corporation | High strength galvanized steel sheet having excellent formability and method for manufacturing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3144572B2 (en) | 2001-03-12 |
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