JPH0123525B2 - - Google Patents
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- Publication number
- JPH0123525B2 JPH0123525B2 JP58145658A JP14565883A JPH0123525B2 JP H0123525 B2 JPH0123525 B2 JP H0123525B2 JP 58145658 A JP58145658 A JP 58145658A JP 14565883 A JP14565883 A JP 14565883A JP H0123525 B2 JPH0123525 B2 JP H0123525B2
- Authority
- JP
- Japan
- Prior art keywords
- less
- hot
- steel
- temperature
- strength
- 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
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- 229910000831 Steel Inorganic materials 0.000 claims description 37
- 239000010959 steel Substances 0.000 claims description 37
- 238000005098 hot rolling Methods 0.000 claims description 14
- 238000001816 cooling Methods 0.000 claims description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 229910001208 Crucible steel Inorganic materials 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 4
- 229910052720 vanadium Inorganic materials 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 238000005096 rolling process Methods 0.000 description 13
- 230000000694 effects Effects 0.000 description 11
- 238000004804 winding Methods 0.000 description 7
- 238000005275 alloying Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 229910052758 niobium Inorganic materials 0.000 description 3
- 238000009749 continuous casting Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000010583 slow cooling Methods 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000002436 steel type Substances 0.000 description 2
- 238000005482 strain hardening Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000007373 indentation Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004881 precipitation hardening Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Description
本発明は、冷間加工性に優れた、45Kg／mm2以上
の高強度を有する熱延高張力鋼板を極めて低コス
トで製造する方法、特に、Ｃ―低Si―低Mn系鋼
に対して低温圧延を行つた後、急冷を行い、次い
で低温で巻取る熱延高張力鋼板の製造法に関す
る。
従来、高張力鋼板としては、例えば、0.09％Ｃ
―0.5％Si―1.50％Mn―0.03％Nb鋼などのよう
に、合金元素添加量が多い高Si―高Mn系鋼が一
般的であつた（例：特開昭54−65118号）。
しかし、かかる従来の熱延高張力鋼板は、Si，
Mnなどの合金元素を多量に使用しているため高
コストになるばかりでなく、連続鋳造法によつて
得た連続鋳造スラブ（以下、CCスラブという）
の割れも発生しやすい。したがつて、省エネルギ
ーの利点があることから近年広く実施されてい
る、連続鋳造に続いて熱間圧延を直ちに直接行
う、いわゆる直接圧延をこの種の鋼に実施しよう
としても、スラブ手入れが必要である等のためそ
の適用はかなり困難である。また、Si含有量が高
いと脱スケール性が劣化するため、熱間圧延中に
スケールの脱離が速やかに行われず、得られる熱
延板にスケールの押込み疵が見られ、商品の価値
が低下するばかりでなく、かかる表面性状の劣化
に基づき冷間加工性、さらには疲労特性が劣化す
るなどの欠陥が生じる。
ここに、本発明者らは、上記従来技術の諸問題
の解決を図るべくまず低Si―低Mn系鋼とすると
ともに、さらに、そのようにSi、Mnの含有量を
低下させても従来の高Si―高Mn系熱延高張力鋼
板と同程度の高強度と加工性とを具備した鋼板を
得るべく鋭意検討した結果、Ｃ―低Si―低Mn系
鋼に対して、低温圧延後、急冷し、次いで450℃
以下で巻取ることによつて、従来の熱延高張力鋼
板並みの高強度と冷間加工性が確保される高張力
鋼板が得られることを見い出して本発明を完成し
たものである。
よつて、本発明の要旨とするところは、
重量％で、
Ｃ：0.02〜0.25％、Si：0.14％以下、
Mn：0.02〜0.28％、Ｐ：0.025％以下、
Ｓ：0.005％以下、sol.Al：0.01〜0.10％、
残部実質的に鉄
から成る組成を有する鋳鋼片を熱間圧延してAr3
点未満650℃以上で熱間圧延を終了後、50℃／sec
以上の急冷を行い、次いで450℃以下で巻取るこ
とを特徴とする、熱延高張力鋼板の製造法であ
る。
さらに、本発明にあつては、上記鋳鋼片は、所
望により、Ca：0.0100％以下、および／または、
Nb：0.05％以下、Ｖ：0.05％以下およびTi：0.05
％以下の１種または２種以上、および／または、
Ｂ：0.0050％以下を含有してもよい。
なお、本発明にあつて、上記鋳鋼片は連続鋳造
鋳片、つまりCCスラブであつてもよく、あるい
は分塊圧延により得られた鋼片、つまり分塊スラ
ブであつてもよい。また、いずれの場合にも熱間
圧延に先立つて、再加熱しても、あるいは加熱す
ることなく熱鋳鋼片のまま直接に熱間圧延工程に
送つても良い。
しかしながら、前述のいわゆる直接圧延の利点
を考えた場合、本発明の好適態様としては、上記
鋳鋼片としてはCCスラブを利用し、しかもそれ
を再加熱することなく直接熱間圧延工程に送る直
接圧延法を採用するのが好ましい。
次に、本発明において鋼組成および圧延条件を
上述のように限定した理由について以下詳述す
る。
Ｃ：
Ｃは、特に本発明の製造条件下では、硬質第２
相（例えば、微細パーライト、擬似パーライ
ト、ベイナイトなど）の体積率を増大させ、鋼
板の強度を高めて、容易に45Kg／mm2以上の引張
強さを付与する作用があるが、その含有量が
0.02％未満では所望の強度が得られず、一方、
0.25％を越えて含有させると、溶接性が劣化す
る。なお、50Kg／mm2以上の引張強さの高張力鋼
板を経済的に得るには、Ｃは好ましくは0.06％
以上添加するのが良い。
Si：
Siは、固溶硬化作用により、鋼板の強度を上げ
る作用があるが、鋼板の表面性状を改善しそし
て低コスト化を図るためにはこの元素も節約す
ることが必要である。したがつて、本発明にあ
つて、Siを0.14％以下とする。好ましくは、
0.10％以下である。
Mn：
Mnは、鋼の焼入れ性を改善して鋼板の強度を
上昇させる作用を有するが、本発明におけるよ
うなＣ強化鋼においては、むしろ、Mn含有量
を低下させて、焼入れ性を低下させる方が冷間
加工性に有利である。また、冷間での加工割れ
などを引き起こすMnSを減少させる意味から
もMnを低下させる方が冷間加工性に有利であ
る。したがつて、合金元素の節約、CCスラブ
の割れ対策なども考え合せて、本発明にあつて
はMn含有量を0.28％以下に制限する。好まし
くは、0.20％以下である。
なお、下限はＳを安定化させて熱間加工時の
脆化防止を図るため0.02％とする。
Ｐ：
Ｐは、CCスラブから製造した鋼板などにおい
て中心偏析部の硬度を高めて、冷間加工時に割
れを生じさせやすい。したがつて、可能な限り
少ない方が望ましい。本発明にあつては、経済
的見地より0.025％以下とするが、好ましくは
0.010％以下である。
Ｓ：
Ｓは、Mnと結合してMnSとなりＡ系介在物を
生じ冷間加工性を劣化させる。またＳが高いと
熱間加工時に脆化を生じやすい。したがつて、
Ｓも可能な限り少ない方が望ましい。本発明に
あつては、経済的な見地より0.005％以下とす
るが、好ましくは0.002％以下である。
Sol.Al：
Sol.Alは脱酸剤として有効であり、したがつ
て、脱酸の効果が期待される0.01％を下限と
し、一方、脱酸の効果が飽和する0.10％を上限
とする。
Nb、Ｖ、Ti：
これらの元素はいずれも、Ｃ（あるいはＮ）と
結合して微細析出物を形成し、大きい析出硬化
を生じる。しかし、あまり多量に添加すると、
前述の硬質第２相が減少し、析出物が粗大化し
たInterstitial Free鋼となりやすく逆に強度が
低下するので、それぞれの元素の添加量を0.05
％以下とする。
Ｂ：
Ｂは微量添加するだけで大巾に鋼の焼入れ性を
向上させ得る好ましい元素である。しかし、一
定含有量以上の添加はCCスラブの割れ増加に
つながるばかりでなく、鋼の焼入れ性効果も飽
和し、かえつてコスト高をもたらす。したがつ
て、Ｂを添加する場合、その上限を0.0050％と
する。
Ca：
Caは脱Ｓ効果以外にAl2O3、MnSと結合して
Ａ系、Ｂ系介在物をＣ系介在物に変化させる作
用がある。したがつて、Caはこの効果により
本発明にかかる熱延高張力鋼板の冷間加工性を
大巾に改善する好ましい元素である。しかし、
多量に添加すると鋼中の介在物が増加してむし
ろ冷間加工性は劣化する。したがつて、Ca添
加の上限は0.0100％とする。
なお、上述の所望添加元素としてのNb，Ｖ，
Ti、さらにはＢまたはCaはそれらの内少なくと
も１種を適宜選択して添加することができる。
その他、付随不純物としてはＮ等が含まれる
が、好ましくはＮは0.02％以下に制限する。
熱間圧延終了温度：
本発明にあつては、Ar3点未満650℃以上の温
度で圧延を終了するが、しかし、もしAr3点以上
の温度で圧延を終了すると熱間圧延による組織の
微粒化効果が期待されず、特に、本発明にかかる
方法のように、Ｃにより高強度を得ようとする場
合には、むしろ冷間加工性の劣化が大きい。
また、650℃より低い温度で圧延を終了すると、
変態後のフエライトを著しく加工してしまうこと
になり、そのため大きい異方性を生じて冷間加工
性が劣化する。しかも、650℃より低い温度で圧
延を終了するようにすると、熱間変形抵抗が著し
く高くなり実際上かなり圧延が困難となる。
なお、圧延開始温度はAr3点以上であれば特に
制限されない。一般には1050℃以上である。
熱間圧延後の冷却・巻取条件：
熱間圧延後の冷却速度が50℃／secより小さい
と、十分な焼入れ効果が生じず硬化組織が得難
く、所望の高強度が得られない。なお、好ましく
は、冷却速度は可能な限り速い方がよいことは言
うまでもない。
しかし、一方、50℃／secより速い冷却速度の
場合であつても、冷却後、450℃より高温で巻取
ると巻取後の除冷によりやはり組織が軟化して所
望の高強度が得られない。
なお、巻取温度に関しては、450℃以下、好ま
しくは450〜100℃で巻取るのが良い。100℃より
低い温度だと巻取後の除冷に基づくフエライト地
中の固溶Ｃ減少効果が低下してやはり冷間加工性
が劣化するからである。
次に実施例によつて本発明をさらに説明する。
実施例
第１表に示す化学組成の各供試材を溶製し、第
２表に示す条件下でそれぞれ熱間圧延を施した。
第１表には、参考までに各鋼種のAr3点を示して
おく。
得られた熱延鋼板についての各機械的性質を同
じく第２表にまとめて示す。
試験番号１、14〜17はいずれも同一鋼種Ａを使
用しており、それぞれ熱間圧延条件を変えた場合
を示す。本発明の条件を外れる場合、つまり熱間
圧延条件を外れるときは冷間加工性が良くなく
（例：試験番号15）、また圧延温度、冷却・巻取条
件が外れるとき低強度（例：試験番号14，16，
17）となつている。
また、試験番号８〜13の場合は、いずれも鋼の
化学組成が本発明のそれを外れるものであつて、
それらは著しく低強度であるか（例：試験番号
８，11）、または高強度であつても冷間加工性が
良くない（例：試験番号９，10，12，13）。
このように、第２表に示す結果からも明らかな
ように、本発明に係る場合（試験番号１〜７）、
得られる熱延鋼板はいずれも高強度で冷間加工性
もすぐれている。特に、Caを添加した試験番号
２、４および７の場合、高強度でしかも著しく良
好な冷間加工性を有する熱延鋼板が得られる。
The present invention provides a method for producing hot-rolled high-strength steel sheets with excellent cold workability and high strength of 45 kg/mm 2 or more at an extremely low cost, particularly for C-low Si-low Mn steels. The present invention relates to a method for manufacturing a hot-rolled high-strength steel sheet, which involves low-temperature rolling, rapid cooling, and then low-temperature winding. Conventionally, for example, 0.09% C
-0.5%Si-1.50%Mn-0.03%Nb steel, high Si-high Mn steels with a large amount of alloying elements added were common (eg, JP-A-54-65118). However, such conventional hot-rolled high-strength steel sheets contain Si,
Continuously cast slabs (hereinafter referred to as CC slabs) obtained by the continuous casting method are not only expensive due to the use of large amounts of alloying elements such as Mn.
Cracks are also likely to occur. Therefore, even if attempts are made to apply so-called direct rolling to this type of steel, in which continuous casting is immediately followed by hot rolling, which has been widely practiced in recent years due to its energy-saving benefits, slab maintenance is required. Its application is quite difficult due to the following reasons. In addition, when the Si content is high, the descaling performance deteriorates, so the scale is not removed quickly during hot rolling, and the resulting hot rolled sheet has scale indentation defects, reducing the value of the product. Not only this, but also defects such as deterioration of cold workability and fatigue properties occur due to such deterioration of surface properties. Here, the present inventors first developed a low Si-low Mn steel in order to solve the problems of the above-mentioned prior art, and furthermore, even if the content of Si and Mn was reduced in this way, the conventional steel As a result of intensive study to obtain a steel plate with high strength and workability comparable to high-Si-high-Mn hot-rolled high-strength steel sheets, we found that after low-temperature rolling, C-low-Si-low-Mn steel Rapid cooling then 450℃
The present invention was completed by discovering that a high-strength steel plate having the same high strength and cold workability as conventional hot-rolled high-strength steel plates can be obtained by winding the hot-rolled steel plate in the following manner. Therefore, the gist of the present invention is as follows: C: 0.02 to 0.25%, Si: 0.14% or less, Mn: 0.02 to 0.28%, P: 0.025% or less, S: 0.005% or less, sol. Al: 0.01~0.10%, the balance essentially iron is hot rolled into Ar 3
50℃/sec after hot rolling is completed at 650℃ or more below the point
This is a method for producing a hot-rolled high-strength steel sheet, which is characterized by performing the above quenching and then winding at 450°C or less. Furthermore, in the present invention, the cast steel piece may contain Ca: 0.0100% or less, and/or
Nb: 0.05% or less, V: 0.05% or less and Ti: 0.05
% or less of one or more kinds, and/or
B: 0.0050% or less may be contained. In the present invention, the cast steel slab may be a continuously cast slab, that is, a CC slab, or may be a steel slab obtained by blooming rolling, that is, a bloomed slab. Further, in any case, prior to hot rolling, the hot cast steel billet may be reheated or directly sent to the hot rolling process without being heated. However, when considering the advantages of so-called direct rolling described above, a preferred embodiment of the present invention is to use a CC slab as the cast steel slab, and directly send it to the hot rolling process without reheating. It is preferable to adopt the law. Next, the reason why the steel composition and rolling conditions are limited as described above in the present invention will be explained in detail below. C: C, especially under the manufacturing conditions of the present invention, is a hard second
It has the effect of increasing the volume fraction of phases (e.g., fine pearlite, pseudo pearlite, bainite, etc.), increasing the strength of the steel sheet, and easily imparting a tensile strength of 45 kg/mm2 or more .
If it is less than 0.02%, the desired strength cannot be obtained;
If the content exceeds 0.25%, weldability will deteriorate. In addition, in order to economically obtain a high tensile strength steel plate with a tensile strength of 50 Kg/mm 2 or more, C is preferably 0.06%.
It is better to add more than that. Si: Si has the effect of increasing the strength of steel sheets through solid solution hardening, but it is necessary to save this element in order to improve the surface properties of steel sheets and reduce costs. Therefore, in the present invention, Si is set to 0.14% or less. Preferably,
It is 0.10% or less. Mn: Mn has the effect of improving the hardenability of steel and increasing the strength of the steel plate, but in C-strengthened steel as in the present invention, it rather reduces the Mn content and decreases the hardenability. This is more advantageous in terms of cold workability. In addition, lowering Mn is advantageous for cold workability in terms of reducing MnS, which causes cold working cracks. Therefore, in consideration of saving alloying elements and preventing cracks in the CC slab, the Mn content is limited to 0.28% or less in the present invention. Preferably it is 0.20% or less. The lower limit is set to 0.02% in order to stabilize S and prevent embrittlement during hot working. P: P increases the hardness of the center segregation area in steel plates manufactured from CC slabs, making it more likely to cause cracks during cold working. Therefore, it is desirable to have as few as possible. In the present invention, from an economical point of view, it is set to 0.025% or less, but preferably
It is 0.010% or less. S: S combines with Mn to become MnS, producing A-based inclusions and deteriorating cold workability. Moreover, when S is high, embrittlement tends to occur during hot working. Therefore,
It is also desirable for S to be as small as possible. In the present invention, from an economic standpoint, the content is set to 0.005% or less, preferably 0.002% or less. Sol.Al: Sol.Al is effective as a deoxidizing agent. Therefore, the lower limit is set at 0.01%, at which the deoxidizing effect is expected, and the upper limit is set at 0.10%, at which the deoxidizing effect is saturated. Nb, V, Ti: All of these elements combine with C (or N) to form fine precipitates, resulting in large precipitation hardening. However, if too much is added,
The above-mentioned hard second phase decreases and the precipitates become coarser, resulting in Interstitial Free steel, which tends to decrease in strength, so the amount of each element added is reduced to 0.05.
% or less. B: B is a preferable element that can significantly improve the hardenability of steel by adding only a small amount. However, addition of more than a certain amount not only leads to increased cracking of the CC slab, but also saturates the hardenability effect of the steel, resulting in higher costs. Therefore, when adding B, the upper limit is 0.0050%. Ca: Ca has the effect of converting A-based and B-based inclusions into C-based inclusions by combining with Al 2 O 3 and MnS, in addition to the S-removal effect. Therefore, Ca is a preferable element that greatly improves the cold workability of the hot-rolled high-strength steel sheet according to the present invention due to this effect. but,
If added in a large amount, inclusions in the steel will increase and cold workability will actually deteriorate. Therefore, the upper limit of Ca addition is 0.0100%. Note that Nb, V,
At least one of Ti, B or Ca can be appropriately selected and added. Other incidental impurities include N and the like, but N is preferably limited to 0.02% or less. Hot rolling termination temperature: In the present invention, rolling is terminated at a temperature of 650°C or higher below Ar 3. However, if rolling is terminated at a temperature of Ar 3 or higher, fine grains in the structure due to hot rolling will occur. In particular, when high strength is to be obtained by C as in the method according to the present invention, the deterioration of cold workability is rather large. Also, if rolling is finished at a temperature lower than 650℃,
The ferrite after transformation is significantly processed, resulting in large anisotropy and poor cold workability. Moreover, if rolling is terminated at a temperature lower than 650° C., the hot deformation resistance becomes extremely high, making rolling actually quite difficult. Note that the rolling start temperature is not particularly limited as long as it is Ar 3 points or higher. Generally the temperature is 1050℃ or higher. Cooling and coiling conditions after hot rolling: If the cooling rate after hot rolling is lower than 50° C./sec, a sufficient hardening effect will not occur, making it difficult to obtain a hardened structure, and the desired high strength will not be obtained. Note that it goes without saying that preferably the cooling rate is as fast as possible. However, even if the cooling rate is faster than 50°C/sec, if the winding is performed at a temperature higher than 450°C after cooling, the structure will still soften due to slow cooling after winding and the desired high strength will not be obtained. do not have. Note that the winding temperature is preferably 450°C or lower, preferably 450 to 100°C. This is because if the temperature is lower than 100°C, the effect of reducing solid solution C in the ferrite ground due to slow cooling after coiling will be reduced, and the cold workability will also deteriorate. Next, the present invention will be further explained with reference to Examples. Examples Each sample material having the chemical composition shown in Table 1 was melted and hot rolled under the conditions shown in Table 2.
Table 1 shows three Ar points for each steel type for reference. The mechanical properties of the obtained hot rolled steel sheets are also summarized in Table 2. Test numbers 1 and 14 to 17 all use the same steel type A, and show cases where the hot rolling conditions were changed. When the conditions of the present invention are not met, that is, when the hot rolling conditions are not met, the cold workability is poor (e.g. test number 15), and when the rolling temperature, cooling and winding conditions are not met, the strength is low (e.g. test number 15). Number 14, 16,
17) In addition, in the case of test numbers 8 to 13, the chemical composition of the steel deviates from that of the present invention,
They either have extremely low strength (eg test numbers 8, 11) or have high strength but poor cold workability (eg test numbers 9, 10, 12, 13). In this way, as is clear from the results shown in Table 2, in the case of the present invention (test numbers 1 to 7),
All of the hot rolled steel sheets obtained have high strength and excellent cold workability. In particular, in the case of test numbers 2, 4, and 7 in which Ca was added, hot rolled steel sheets with high strength and extremely good cold workability were obtained.
【表】【table】
【表】【table】
Claims (1)
未満650℃以上で熱間圧延を終了後、50℃／sec以
上の急冷を行い、次いで450℃以下で巻取ること
を特徴とする、熱延高張力鋼板の製造法。 ２ 重量％で、 Ｃ：0.02〜0.25％、Si：0.14％以下、 Mn：0.02〜0.28％、Ｐ：0.025％以下、 Ｓ：0.005％以下、sol.Al：0.01〜0.10％、 さらに下記の(i)〜(iii)群から選んだ１種または２
種以上； (i) Nb：0.05％以下、Ｖ：0.05％以下および
Ti：0.05％以下の少なくとも１種、 (ii) Ca：0.0100％以下、および (iii) Ｂ：0.0050％以下、 残部実質的に鉄 から成る組成を有する鋳鋼片を熱間圧延してAr3
未満650℃以上で熱間圧延を終了後、50℃／sec以
上の急冷を行い、次いで450℃以下で巻取ること
を特徴とする、熱延高張力鋼板の製造法。[Claims] 1% by weight: C: 0.02-0.25%, Si: 0.14% or less, Mn: 0.02-0.28%, P: 0.025% or less, S: 0.005% or less, sol.Al: 0.01-0.10 %, a cast steel billet with a composition consisting essentially of iron is hot-rolled to form Ar 3
A method for producing a hot-rolled high-strength steel sheet, which comprises hot rolling at a temperature of 650°C or higher, followed by rapid cooling at a rate of 50°C/sec or higher, and then coiling at a temperature of 450°C or lower. 2% by weight, C: 0.02-0.25%, Si: 0.14% or less, Mn: 0.02-0.28%, P: 0.025% or less, S: 0.005% or less, sol.Al: 0.01-0.10%, and the following ( One or two selected from groups i) to (iii)
(i) Nb: 0.05% or less, V: 0.05% or less, and
At least one of Ti: 0.05% or less, (ii) Ca: 0.0100% or less, and (iii) B: 0.0050% or less, with the remainder essentially iron, is hot-rolled and Ar 3
A method for producing a hot-rolled high-strength steel sheet, which comprises hot rolling at a temperature of 650°C or higher, followed by rapid cooling at a rate of 50°C/sec or higher, and then coiling at a temperature of 450°C or lower.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14565883A JPS6039119A (en) | 1983-08-11 | 1983-08-11 | Manufacture of hot-rolled high-tension steel plate |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14565883A JPS6039119A (en) | 1983-08-11 | 1983-08-11 | Manufacture of hot-rolled high-tension steel plate |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6039119A JPS6039119A (en) | 1985-02-28 |
| JPH0123525B2 true JPH0123525B2 (en) | 1989-05-02 |
Family
ID=15390095
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14565883A Granted JPS6039119A (en) | 1983-08-11 | 1983-08-11 | Manufacture of hot-rolled high-tension steel plate |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6039119A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH079035B2 (en) * | 1988-08-05 | 1995-02-01 | 川崎製鉄株式会社 | Method of manufacturing hot rolled high strength steel sheet |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5395121A (en) * | 1977-02-01 | 1978-08-19 | Nippon Kokan Kk <Nkk> | Preparation of high tensile steel sheet |
| JPS5544590A (en) * | 1978-09-26 | 1980-03-28 | Kawasaki Steel Corp | Production of high tensile thin steel plate of superior cold workability |
| JPS5684422A (en) * | 1979-12-14 | 1981-07-09 | Sumitomo Metal Ind Ltd | Production of precipitation hardening type high-tension cold rolled steel plate |
| JPS58130221A (en) * | 1982-01-29 | 1983-08-03 | Sumitomo Metal Ind Ltd | Manufacture of hot rolling high tension steel plate for working |
-
1983
- 1983-08-11 JP JP14565883A patent/JPS6039119A/en active Granted
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5395121A (en) * | 1977-02-01 | 1978-08-19 | Nippon Kokan Kk <Nkk> | Preparation of high tensile steel sheet |
| JPS5544590A (en) * | 1978-09-26 | 1980-03-28 | Kawasaki Steel Corp | Production of high tensile thin steel plate of superior cold workability |
| JPS5684422A (en) * | 1979-12-14 | 1981-07-09 | Sumitomo Metal Ind Ltd | Production of precipitation hardening type high-tension cold rolled steel plate |
| JPS58130221A (en) * | 1982-01-29 | 1983-08-03 | Sumitomo Metal Ind Ltd | Manufacture of hot rolling high tension steel plate for working |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6039119A (en) | 1985-02-28 |
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