JPH02282418A - Production of high tensile strength steel sheet excellent in internal quality and workability - Google Patents
Production of high tensile strength steel sheet excellent in internal quality and workabilityInfo
- Publication number
- JPH02282418A JPH02282418A JP10163989A JP10163989A JPH02282418A JP H02282418 A JPH02282418 A JP H02282418A JP 10163989 A JP10163989 A JP 10163989A JP 10163989 A JP10163989 A JP 10163989A JP H02282418 A JPH02282418 A JP H02282418A
- Authority
- JP
- Japan
- Prior art keywords
- less
- steel
- toughness
- temp
- workability
- 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.)
- Granted
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 38
- 239000010959 steel Substances 0.000 title claims abstract description 38
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 238000001816 cooling Methods 0.000 claims abstract description 17
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 4
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 4
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 4
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 3
- 238000005096 rolling process Methods 0.000 abstract description 15
- 238000010438 heat treatment Methods 0.000 abstract description 9
- 239000000203 mixture Substances 0.000 abstract description 4
- 238000005496 tempering Methods 0.000 abstract description 3
- 229910052802 copper Inorganic materials 0.000 abstract description 2
- -1 heating temp. Substances 0.000 abstract description 2
- 238000005098 hot rolling Methods 0.000 abstract 2
- 229910052759 nickel Inorganic materials 0.000 abstract 1
- 239000000463 material Substances 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 239000004566 building material Substances 0.000 description 5
- 239000010953 base metal Substances 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 2
- 230000003749 cleanliness Effects 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004881 precipitation hardening Methods 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
この発明は、建築や造船の分野に用途のある引張り強さ
が６０ｋｇｆ／ｍｍｚ以上の高張力鋼板、特に建材用に
好適な内質および加工性の優れた鋼板の製造方法に関す
る。Detailed Description of the Invention (Industrial Application Field) The present invention provides a high tensile strength steel plate with a tensile strength of 60 kgf/mmz or more, which is used in the fields of architecture and shipbuilding, and which has an internal quality and processing that is particularly suitable for use as a building material. The present invention relates to a method for producing steel sheets with excellent properties.
高張力鋼板は複数の鋼板を溶接しＨ型鋼状や中空角柱状
に成形して建材とするが、ここで建材の強度を左右する
溶接継手部の健全性が確保されていること、例えば溶は
込み不良やスラグ巻き込みのないことが肝要である。High-strength steel plates are made into building materials by welding multiple steel plates and forming them into H-shaped steel shapes or hollow prismatic shapes, but the integrity of the welded joints, which determine the strength of the building materials, must be ensured, for example, melting It is important that there is no embedding failure or slag entrainment.
溶接継手部の健全性の評価は、鋼板の表面から斜めの方
向に位置する溶接継手部に向けて超音波探傷を行う方法
（以下斜角ＵＴ法と示す）を用いた検査が一般に実施さ
れている。To evaluate the soundness of welded joints, inspection is generally carried out using an ultrasonic flaw detection method (hereinafter referred to as the oblique UT method) directed toward the welded joint located diagonally from the surface of the steel plate. There is.
斜角ＵＴ法を実施する場合、超音波を伝達させる鋼板の
内部に圧延によって結晶方位が一方向に揃った集合組織
があると、ここで超音波が減衰または曲げられて探傷す
べき対象（溶接継手部）まで伝達されず、いわゆる音響
異方性が生じるため、溶接継手部の健全性を正しく評価
できない。When performing the oblique UT method, if there is a texture in which the crystal orientation is aligned in one direction due to rolling inside the steel plate that transmits the ultrasonic waves, the ultrasonic waves will be attenuated or bent and the object to be detected (weld The soundness of the welded joint cannot be evaluated correctly because the sound is not transmitted to the welded joint and a so-called acoustic anisotropy occurs.
そこでこの音響異方性のない、すなわち内質の優れた高
張力鋼板が、とくに建材の用途において要望されている
。Therefore, there is a demand for high-strength steel sheets that are free of this acoustic anisotropy, that is, have excellent internal quality, especially for use as building materials.
（従来の技術）
高張力鋼板の熱処理法に関して特公昭５５−５００９０
号公報には、鋼材をＡｃ１ｘＡｃ３の温度に加熱した後
焼入れを施し、次いで６００℃以下の温度で焼戻しを施
すことが開示されているが、上記した音響異方性につい
ての記載はなく、さらに熱処理前の鋼材組織によって熱
処理後のしん性が大きく変化する不利がある。(Prior art) Japanese Patent Publication No. 55-50090 on heat treatment method for high-strength steel plates
The publication discloses that the steel material is heated to a temperature of Ac1 x Ac3, then quenched, and then tempered at a temperature of 600°C or less, but there is no mention of the above-mentioned acoustic anisotropy, and no further heat treatment is required. There is a disadvantage that the toughness after heat treatment varies greatly depending on the structure of the previous steel material.
また特公昭５８−１０４４２号公報には圧延に引き続い
て直接焼入れを施す技術が開示されているが、圧延終了
温度が未再結晶域になると集合組織が生成し音響異方性
を生じる。Further, Japanese Patent Publication No. 58-10442 discloses a technique in which direct quenching is performed subsequent to rolling, but when the rolling end temperature falls into the non-recrystallized region, texture is generated and acoustic anisotropy occurs.
（発明が解決しようとする課題）
そこでこの発明は加工性およびじん性に優れかつ圧延後
に集合組織の発生しない高張力鋼板を提供しようとする
ものである。(Problems to be Solved by the Invention) Therefore, it is an object of the present invention to provide a high-strength steel plate that has excellent workability and toughness and does not generate texture after rolling.
（課題を解決するために手段）
この発明は、
Ｃ： ０．２０ｗｔ％（以下単に％と示す）以下、Ｓｔ
： ０．６％以下、
Ｍｎ ： ２．０％以下、
八１７０．００１〜０．１％および
Ｎ ： ０．００６％以下
を含み、さらに
Ｈｌ： １．０％以下、Ｍｏ ： １．０％以下、Ｃｕ
： １．０％以下、Ｃｒ ： １．０％以下、Ｖ：０
．１％以下、Ｎｂ ： ０．１％以下、Ｔｉ ： ０．
１％以下、Ｂ ： ０．００３％以下およびＲＥＭ
： ０．０１％以下から選ばれる少なくとも１種を含有
する鋼スラブを、（Ａｃ３＋２００℃）以下の温度に加
熱し、そして熱間圧延を仕上温度（Ａｒ：＋ ＋１００
”Ｃ）以上で終了した後空冷またはそれ以上の冷却速度
で冷却し、次いでＡｃ１ｘＡｃ３の温度に加熱した後再
び空冷またはそれ以上の冷却速度で冷却し、その後＾ｃ
１以下の温度域での焼戻し処理を施すことを特徴とする
内質および加工性の優れた高張力鋼板の製造方法である
。(Means for Solving the Problems) This invention provides C: 0.20wt% (hereinafter simply referred to as %) or less, St
: 0.6% or less, Mn: 2.0% or less, 8170.001 to 0.1% and N: 0.006% or less, Hl: 1.0% or less, Mo: 1.0% Below, Cu
: 1.0% or less, Cr: 1.0% or less, V: 0
．． 1% or less, Nb: 0.1% or less, Ti: 0.
1% or less, B: 0.003% or less and REM
: A steel slab containing at least one element selected from 0.01% or less is heated to a temperature of (Ac3+200°C) or less, and hot rolled to a finishing temperature (Ar: + +100°C).
``C) After completing the above steps, cool with air cooling or a higher cooling rate, then heat to a temperature of Ac1xAc3, cool again with air cooling or a higher cooling rate, and then ^c
This is a method for producing a high-strength steel sheet with excellent internal quality and workability, which is characterized by performing a tempering treatment in a temperature range of 1 or less.
（作 用） 次に各成分組成範囲の限定理由を説明する。(for production) Next, the reason for limiting the composition range of each component will be explained.
Ｃ：０．２％以下
Ｃは、０．２％を超えると母材じん性の劣化が大きくな
るため、０．２％以下に限定する。なお下限は母材の強
度保証を考慮すると０．０３％とすることが好ましい。C: 0.2% or less C is limited to 0.2% or less because if it exceeds 0.2%, the toughness of the base material will deteriorate significantly. Note that the lower limit is preferably 0.03% in consideration of ensuring the strength of the base material.
Ｓｔ ： ０．６％以下
Ｓｉは脱酸に用いられ好ましくは０．１０％以上は必要
であるが、母材の熱影響部（Ｉ（ＡＺ）のしん性または
溶接性を劣化するため、０．６％以下に限定する。St: 0.6% or less Si is used for deoxidation and is preferably 0.10% or more, but since it deteriorates the toughness or weldability of the heat affected zone (I (AZ)) of the base metal, it is .Limited to 6% or less.
Ｍｎ ： ２．０％以下
Ｍｎは強度およびじん性を同時に向上させる極めて重要
な成分で好ましくは０．６０％以上は必要であるが、多
量に添加すると溶接性とＨＡＺのじ−ん性を劣化するた
め、２．０％以下に限定する。Mn: 2.0% or less Mn is an extremely important component that simultaneously improves strength and toughness, and preferably 0.60% or more is required, but if added in large amounts, it deteriorates weldability and HAZ toughness. Therefore, it is limited to 2.0% or less.
Ａｌ ： ０．００１〜０．１％
八１は脱酸に用いられ０．００１％未満では脱酸が不十
分になり、一方０．１％をこえると鋼の清浄度およびＨ
ＡＺのじん性が劣化するため、０．００１〜０．１％の
範囲に限定する。Al: 0.001-0.1% 81 is used for deoxidation, and if it is less than 0.001%, deoxidation will be insufficient, while if it exceeds 0.1%, the cleanliness of steel and H
Since the toughness of AZ deteriorates, it is limited to a range of 0.001 to 0.1%.
Ｎ ： ０．００６％以下
Ｎは溶鋼中に不可避に混入し鋼のしん性を劣化するため
、０．００６％以下に抑制する。N: 0.006% or less N is unavoidably mixed into molten steel and deteriorates the toughness of the steel, so it is suppressed to 0.006% or less.
この発明においては以上に規定した成分範囲にさらにＮ
ｉ ： １．０％以下、Ｍｏ ： １．０％以下、Ｃｕ
： １．０％以下、Ｃｒ ： １．０％以下、Ｖ：Ｑ
、１％以下、Ｎｂ二０．１％以下、Ｔｉ：０．１％以下
、Ｂ ： ０．００３％以下およびｌ’ｌＢＭ ： ０
．０１％以下から選ばれる少なくとも１種を含有させる
。In this invention, in addition to the component range specified above, N
i: 1.0% or less, Mo: 1.0% or less, Cu
: 1.0% or less, Cr: 1.0% or less, V:Q
, 1% or less, Nb2 0.1% or less, Ti: 0.1% or less, B: 0.003% or less, and l'lBM: 0
．． At least one selected from 0.01% or less is contained.
これらの成分を含有させる主たる目的は強度およびじん
性の向上と製造可能な板厚範囲の拡大とにあり、それぞ
れの添加量は溶接性やＨＡＺでのしん性を阻害しない範
囲に制限する。すなわちＮｉ ： １．０％以下
ＮｉはＨＡＺの硬化性およびじん性に悪影響を及ぼすこ
となく母材の強度およびじん性を向上させ得るが、１．
０％をこえるとＨＡＺの硬化性およびじん性を阻害する
ため、１．０％以下に限定する。The main purpose of including these components is to improve strength and toughness and to expand the range of sheet thickness that can be manufactured, and the amount of each added is limited to a range that does not impede weldability or toughness in the HAZ. That is, Ni: 1.0% or less Ni can improve the strength and toughness of the base material without adversely affecting the hardenability and toughness of the HAZ, but 1.
If it exceeds 0%, the hardenability and toughness of HAZ will be inhibited, so it is limited to 1.0% or less.
Ｍｏ：１．０％以下
Ｍｏは母材の強度およびじん性を向上させ得る成分であ
るが、１．０％をこえると溶接部のしん性および溶接性
の劣化をまねくため、１．０％以下に限定する。Mo: 1.0% or less Mo is a component that can improve the strength and toughness of the base metal, but if it exceeds 1.0%, it will lead to deterioration of the toughness and weldability of the welded part, so 1.0% Limited to the following.
Ｃｕ ： １．０％以下
ＣｕはＮｉと同様の効果にさらに耐食性および耐水素誘
起割れ性に対しても有効であるが、１．０％をこえると
圧延中にクラックが発生し製造が困難になるため、１．
０％以下に限定する。Cu: 1.0% or less Cu has the same effect as Ni and is also effective for corrosion resistance and hydrogen-induced cracking resistance, but if it exceeds 1.0%, cracks occur during rolling and manufacturing becomes difficult. In order to become 1.
Limited to 0% or less.
Ｃｒ ： １．０％以下
Ｃｒは母材の強度を高めるほか耐水素誘起割れ性に対し
ても有効であるが、１．０％をこえると）ＩＡＺの硬化
性を増大してじん性および溶接性を低下させるため、１
．０％以下に限定する。Cr: 1.0% or less Cr increases the strength of the base metal and is also effective against hydrogen-induced cracking, but if it exceeds 1.0%, it increases the hardenability of IAZ and improves toughness and welding. 1.
．． Limited to 0% or less.
Ｖ：０．１％以下
■は析出硬化に有効であるが、０．１％をこえると溶接
性の劣化をまねくため、０．１％以下に限定する。V: 0.1% or less (2) is effective for precipitation hardening, but if it exceeds 0.1%, weldability deteriorates, so it is limited to 0.1% or less.
Ｎｂ ： ０．１％以下
Ｎｂは析出硬化に有効であるが、０．１％をこえるとじ
ん性の劣化をまねくため、０．１％以下に限定する。Nb: 0.1% or less Nb is effective for precipitation hardening, but if it exceeds 0.1%, the toughness deteriorates, so it is limited to 0.1% or less.
Ｔｉ ： ０．１％以下
Ｔｉはオーステナイト粒の細粒化に有効であるが、０．
１％をこえると溶接性の劣化をまねくため、０．１％以
下に限定する。Ti: 0.1% or less Ti is effective for refining austenite grains, but 0.1% or less Ti is effective for refining austenite grains.
If it exceeds 1%, weldability deteriorates, so it is limited to 0.1% or less.
Ｂ ： ０．００３％以下
Ｂは高強度化に有効であるが、０．００３％をこえると
ＨＡＺのじん性を著しく劣化するため、０．００３％以
下に限定する。B: 0.003% or less B is effective in increasing strength, but if it exceeds 0.003%, the toughness of the HAZ will deteriorate significantly, so it is limited to 0.003% or less.
ＲＥＭ ： ０．０１％以下
ＲＥ−はＭｎＳを球状化してシャルピー吸収エネルギー
を上昇させるほか、圧延によって延伸化したＭｎＳおと
び水素による内部欠陥の発生を防止する。しかし０．０
１％をこえるとＲＥＭの硫化物や硫酸化物が大量に生成
して大型介在物となって、母材のしん性および溶接性の
みならず鋼の清浄度を低下させるため、０．０１％以下
に限定する。REM: 0.01% or less RE- not only spheroidizes MnS and increases the Charpy absorption energy, but also prevents the occurrence of internal defects due to MnS and hydrogen stretched by rolling. But 0.0
If it exceeds 1%, a large amount of REM sulfides and sulfides will form and become large inclusions, reducing not only the toughness and weldability of the base metal but also the cleanliness of the steel, so it should be 0.01% or less. limited to.
次に上記の組成になる鋼スラブに、（Ａｃｚ ＋ ２０
０℃）以下の温度での低温加熱を施す。Next, to the steel slab having the above composition, (Acz + 20
Perform low-temperature heating at a temperature below 0°C.
スラブ加熱温度を（Ａｃｓ ＋ ２００″Ｃ）以下とし
たのは、結晶粒の粗大化防止および圧延母板のじん性向
上をはかるためである。すなわち第１図にスラブ加熱温
度と１粒径との関係を示すように、（Ａｃ３＋２００℃
）をこえると１粒が粗大化することがわかる。またＡＣ
ｌをこえた温度域に粗大粒との混合域があるが、じん性
に影響を与えるほどではない。The purpose of setting the slab heating temperature below (Acs + 200"C) is to prevent coarsening of crystal grains and improve the toughness of the rolling mother plate. In other words, Figure 1 shows the relationship between slab heating temperature and grain size. As shown in the relationship (Ac3+200℃
), it can be seen that one grain becomes coarser. Also AC
There is a mixing area with coarse particles in the temperature range exceeding 1,000 liters, but this is not enough to affect the toughness.
なお同図は、Ｃ：ｏ、ｏ７％、Ｓｉ ： ０．２３％、
Ｍｎ ： １．４５％、Ａｌ ７０．０２６％、Ｎｂ
： ０．０２５％、Ｎ ： ０．００３６％、Ｐ ：
０．０１８％およびＳ ： ０．００３％を含有する鋼
スラブを対象とした測定結果を示し、Ａｃ、点は９０７
”Ｃである。In addition, the same figure shows C: o, o7%, Si: 0.23%,
Mn: 1.45%, Al 70.026%, Nb
: 0.025%, N: 0.0036%, P:
Showing the measurement results for a steel slab containing 0.018% and S: 0.003%, Ac, point is 907
“It is C.
次いで圧延を施すに当たり、仕上げ温度（Ａｒ３＋１０
０℃）以上で終了することが肝要である。すなわち（Ａ
ｒ３＋ １００℃）以上にて圧延を終了することによっ
て、未再結晶域での圧下を極力防止し集合Ｎｉ織の生成
を抑制し、音響異方性の発生を回避するわけである。例
えば第２図に示すように、（Ａｒｚ ＋１００℃）以上
で圧延を終了すると鋼板内の横波速度比は１．００にな
るか１．００に近すき、音響異方性のない鋼板が得られ
ていることがわかる。ここで横波速度比は探触子の振動
方向をＬ方向（圧延方向と平行）、Ｃ方向（圧延方向と
直角）にそれぞれそろえ、得られた横波音速値の比を小
数点２桁まで求め速度比とするものである。Next, when rolling is performed, the finishing temperature (Ar3+10
It is important to finish the process at a temperature of 0°C or higher. That is, (A
By terminating the rolling at a temperature higher than r3+100° C., reduction in the unrecrystallized region is prevented as much as possible, the formation of aggregated Ni textures is suppressed, and the occurrence of acoustic anisotropy is avoided. For example, as shown in Figure 2, when rolling is finished at (Arz +100°C) or higher, the shear wave velocity ratio in the steel plate becomes 1.00 or close to 1.00, and a steel plate without acoustic anisotropy is obtained. You can see that Here, the shear wave velocity ratio is determined by aligning the vibration directions of the probe in the L direction (parallel to the rolling direction) and the C direction (perpendicular to the rolling direction), and calculating the ratio of the obtained shear wave sound velocity values to two decimal places. That is.
なお上記の仕上げ温度は高温であるが、スラブ加熱温度
を低くして細粒化をはかっているため、粗粒化によって
じん性が低下することはない。Although the finishing temperature mentioned above is high, since the slab heating temperature is lowered to achieve finer grain size, the toughness does not decrease due to coarser grain size.
さらに圧延後に空冷またはそれ以上の冷却速度で冷却し
、次いでＡｃｔ−Ａｃ１の温度に加熱した後再び空冷ま
たはそれ以上の冷却速度で冷却し、その後ＡｃＩ以下の
温度域での焼戻し処理を施す。この操作によって組織を
フェライト＋（マルテンサイトまたはベイナイト）にし
、優れたしん性を確保する。Further, after rolling, it is cooled by air cooling or a cooling rate higher than that, then heated to a temperature of Act-Ac1, and then cooled again by air cooling or a cooling rate higher than that, and then subjected to a tempering treatment in a temperature range of AcI or lower. This operation changes the structure to ferrite+ (martensite or bainite) and ensures excellent toughness.
なお上記した空冷とは、大気中にて鋼板を放冷した場合
の冷却方法をいい、たとえば板厚５０ｍｍでは０．２℃
／ｓ程度の冷却速度である。Note that the above-mentioned air cooling refers to a cooling method in which a steel plate is left to cool in the atmosphere; for example, for a plate thickness of 50 mm, the temperature is 0.2°C
The cooling rate is about /s.
（実施例）
表１に示す成分組成の鋼スラブ（３１０ｍｍ厚）を、そ
れぞれ表２に示す製造工程によって鋼板とし、得られた
鋼板の機械的特性および内質について評価した結果を表
３にそれぞれ示す。(Example) Steel slabs (310 mm thick) having the compositions shown in Table 1 were made into steel plates by the manufacturing process shown in Table 2, and the results of evaluating the mechanical properties and internal quality of the obtained steel plates are shown in Table 3. show.
なお機械的特性はＪＩＳ Ｚ２２４１および同２２４２
に準拠した試験の結果を示し、また内質は音響異方性を
考慮しＪＩＳＺ３０６０ （、横波音速比１．０２以下
）にて評価した。The mechanical properties are in accordance with JIS Z2241 and 2242.
The internal quality was evaluated in accordance with JIS Z3060 (transverse wave sound speed ratio 1.02 or less) in consideration of acoustic anisotropy.
表３より、この発明法で得たものは強度およびじん性が
ともに優れ、さらに音響異方性のないことがわかる。Table 3 shows that the material obtained by the method of this invention has excellent strength and toughness, and has no acoustic anisotropy.
（発明の効果）
以上説明したようにこの発明によれば、加工性に優れか
つ音響異方性のない高じん性高張力鋼板を製造すること
ができ、とくに建材の用途に好適な鋼板を提供し得る。(Effects of the Invention) As explained above, according to the present invention, it is possible to produce a high-toughness, high-strength steel plate with excellent workability and no acoustic anisotropy, and to provide a steel plate particularly suitable for use as a building material. It is possible.
第１図はスラブ加熱温度とγ粒径との関係を示すグラフ
、
第２図は圧延仕上げ温度と横波速度比との関係を示すグ
ラフ、
である。
ズラグ７０射すュ度 （０Ｃ）FIG. 1 is a graph showing the relationship between slab heating temperature and γ grain size, and FIG. 2 is a graph showing the relationship between rolling finishing temperature and shear wave velocity ratio. Zurag 70 radiation degree (0C)
Claims (1)
ｕ：１．０ｗｔ％以下、Ｃｒ：１．０ｗｔ％以下、Ｖ：
０．１ｗｔ％以下、Ｎｂ：０．１ｗｔ％以下、Ｔｉ：０
．１ｗｔ％以下、Ｂ：０．００３ｗｔ％以下およびＲＥ
Ｍ：０．０１ｗｔ％以下から選ばれる少なくとも１種を
含有する鋼スラブを、（Ａｃ＿３＋２００℃）以下の温
度に加熱し、そして熱間圧延を仕上温度（Ａｒ＿３＋１
００℃）以上で終了した後空冷またはそれ以上の冷却速
度で冷却し、次いでＡｃ＿１〜Ａｃ＿３の温度に加熱し
た後再び空冷またはそれ以上の冷却速度で冷却し、その
後Ａｃ＿１以下の温度域での焼戻し処理を施すことを特
徴とする内質および加工性の優れた高張力鋼板の製造方
法。[Claims] 1. C: 0.20 wt% or less, Si: 0.6 wt% or less, Mn: 2.0 wt% or less, Al: 0.001 to 0.1 wt%, and N: 0.006 wt% or less. Including Ni: 1.0wt% or less, Mo: 1.0wt% or less, C
u: 1.0wt% or less, Cr: 1.0wt% or less, V:
0.1wt% or less, Nb: 0.1wt% or less, Ti: 0
．． 1wt% or less, B: 0.003wt% or less and RE
M: A steel slab containing at least one selected from 0.01 wt% or less is heated to a temperature of (Ac_3+200°C) or less, and hot rolled at a finishing temperature (Ar_3+1
00℃) or higher, then cooled with air cooling or a cooling rate higher than that, then heated to a temperature of Ac_1 to Ac_3, then cooled again with air cooling or a cooling rate higher than that, and then tempered in a temperature range of Ac_1 or lower. A method for producing a high-tensile steel sheet with excellent internal quality and workability, which is characterized by subjecting it to a treatment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1101639A JPH0735542B2 (en) | 1989-04-24 | 1989-04-24 | Method for producing high-strength steel sheet with excellent internal quality and workability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1101639A JPH0735542B2 (en) | 1989-04-24 | 1989-04-24 | Method for producing high-strength steel sheet with excellent internal quality and workability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02282418A true JPH02282418A (en) | 1990-11-20 |
| JPH0735542B2 JPH0735542B2 (en) | 1995-04-19 |
Family
ID=14305958
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1101639A Expired - Fee Related JPH0735542B2 (en) | 1989-04-24 | 1989-04-24 | Method for producing high-strength steel sheet with excellent internal quality and workability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0735542B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100489021B1 (en) * | 2000-06-28 | 2005-05-11 | 주식회사 포스코 | A method for manufacturing high tensile high toughness steel having superior internal quality |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5550090A (en) * | 1978-10-07 | 1980-04-11 | Kloeckner Humboldt Deutz Ag | Apparatus for vaporizing carbon by molten metal bath |
| JPS55115921A (en) * | 1979-02-28 | 1980-09-06 | Nippon Steel Corp | Production of high tensile steel plate of low yield ratio |
| JPS5852532A (en) * | 1981-09-24 | 1983-03-28 | Seiichi Okuhara | Color pyrometer |
| JPS63235431A (en) * | 1987-03-24 | 1988-09-30 | Nippon Steel Corp | Manufacture of steel plate excellent in strength and toughness and reduced in acoustic anisotropy |
| JPS6455335A (en) * | 1987-08-26 | 1989-03-02 | Nippon Kokan Kk | Production of high-tensile steel having low yield ratio |
-
1989
- 1989-04-24 JP JP1101639A patent/JPH0735542B2/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5550090A (en) * | 1978-10-07 | 1980-04-11 | Kloeckner Humboldt Deutz Ag | Apparatus for vaporizing carbon by molten metal bath |
| JPS55115921A (en) * | 1979-02-28 | 1980-09-06 | Nippon Steel Corp | Production of high tensile steel plate of low yield ratio |
| JPS5852532A (en) * | 1981-09-24 | 1983-03-28 | Seiichi Okuhara | Color pyrometer |
| JPS63235431A (en) * | 1987-03-24 | 1988-09-30 | Nippon Steel Corp | Manufacture of steel plate excellent in strength and toughness and reduced in acoustic anisotropy |
| JPS6455335A (en) * | 1987-08-26 | 1989-03-02 | Nippon Kokan Kk | Production of high-tensile steel having low yield ratio |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100489021B1 (en) * | 2000-06-28 | 2005-05-11 | 주식회사 포스코 | A method for manufacturing high tensile high toughness steel having superior internal quality |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0735542B2 (en) | 1995-04-19 |
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