公开(公告)号：US06228183B1

公开(公告)日：2001-05-08

申请号：US09123791

申请日：1998-07-28

申请人： Narasimha-Rao V. Bangaru ,  Jayoung Koo ,  Michael J. Luton ,  Clifford W. Petersen ,  Hiroshi Tamehiro ,  Hitoshi Asahi ,  Takuya Hara ,  Yoshio Terada

发明人： Narasimha-Rao V. Bangaru ,  Jayoung Koo ,  Michael J. Luton ,  Clifford W. Petersen ,  Hiroshi Tamehiro ,  Hitoshi Asahi ,  Takuya Hara ,  Yoshio Terada

IPC分类号： C22C3814

CPC分类号： C22C38/06 ,  C21D1/19 ,  C21D8/00 ,  C21D2211/002 ,  C21D2211/008 ,  C22C38/04 ,  C22C38/12 ,  C22C38/14

摘要： An ultra-high strength boron-containing steel having a tensile strength of at least about 900 MPa (130 ksi), a toughness as measured by Charpy V-notch impact test at −40° C. (−40° F.) of at least about 120 joules (90 ft-lbs), and a microstructure comprising predominantly fine-grained lower bainite, fine-grained lath martensite, or mixtures thereof, transformed from substantially unrecrystallized austenite grains and comprising iron and specified weight percentages of the additives: carbon, silicon, manganese, copper, nickel, niobium, vanadium, molybdenum, chromium, titanium, aluminum, calcium, Rare Earth Metals, and magnesium, is prepared by heating a steel slab to a suitable temperature; reducing the slab to form plate in one or more hot rolling passes in a first temperature range in which austenite recrystallizes; further reducing said plate in one or more hot rolling passes in a second temperature range below said first temperature range and above the temperature at which austenite begins to transform to ferrite during cooling; quenching said plate to a suitable Quench Stop Temperature; and stopping said quenching and allowing said plate to air cool to ambient temperature.

摘要翻译： 具有至少约900MPa（130ksi）拉伸强度的超高强度含硼钢，在-40℃（-40°F）下通过夏比V-缺口冲击试验测得的韧性 至少约120焦耳（90ft-lbs），以及由基本上未再结晶的奥氏体晶粒转化并且包含铁和特定重量百分比的添加剂的主要包含细粒度的下贝氏体，细粒状板条马氏体或其混合物的微观结构：碳 通过将钢坯加热到合适的温度来制备硅，锰，铜，镍，铌，钒，钼，铬，钛，​​铝，钙，稀土金属和镁， 在奥氏体重结晶的第一温度范围内，在一个或多个热轧道中将板坯还原成板; 在低于所述第一温度范围的第二温度范围内并且高于在冷却期间奥氏体开始转变为铁素体的温度的一个或多个热轧道中进一步减少所述板; 将所述板淬火至合适的淬火停止温度; 并停止所述淬火并允许所述板空气冷却至环境温度。

公开(公告)号：US06264760B1

公开(公告)日：2001-07-24

申请号：US09123625

申请日：1998-07-28

申请人： Hiroshi Tamehiro ,  Hitoshi Asahi ,  Takuya Hara ,  Yoshio Terada ,  Michael J. Luton ,  Jayoung Koo ,  Narasimha-Rao V. Bangaru ,  Clifford W. Petersen

发明人： Hiroshi Tamehiro ,  Hitoshi Asahi ,  Takuya Hara ,  Yoshio Terada ,  Michael J. Luton ,  Jayoung Koo ,  Narasimha-Rao V. Bangaru ,  Clifford W. Petersen

IPC分类号： C22C3808

CPC分类号： C21D8/0226 ,  C21D1/19 ,  C21D2211/002 ,  C21D2211/008 ,  C22C38/04 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14

摘要： An ultra-high strength steel having excellent ultra-low temperature toughness, a tensile strength of at least about 930 MPa (135 ksi), and a microstructure comprising predominantly fine-grained lower bainite, fine-grained lath martensite, or mixtures thereof, transformed from substantially unrecrystallized austenite grains and comprising iron and specified weight percentages of the additives: carbon, silicon, manganese, copper, nickel, niobium, vanadium, molybdenum, chromium, titanium, aluminum, calcium, Rare Earth Metals, and magnesium, is prepared by heating a steel slab to a suitable temperature; reducing the slab to form plate in one or more hot rolling passes in a first temperature range in which austenite recrystallizes; further reducing said plate in one or more hot rolling passes in a second temperature range below said first temperature range and above the temperature at which austenite begins to transform to ferrite during cooling; quenching said plate to a suitable Quench Stop Temperature; and stopping said quenching and allowing said plate to air cool to ambient temperature.

摘要翻译： 具有优异的超低温韧性，至少约930MPa（135ksi）的拉伸强度和主要包含细粒度的下贝氏体，细粒状板条马氏体或其混合物的微观结构的超高强度钢被转化 来自基本上未再结晶的奥氏体晶粒并且包含铁和指定重量百分比的添加剂：碳，硅，锰，铜，镍，铌，钒，钼，铬，钛，​​铝，钙，稀土金属和镁，由 将钢板加热到合适的温度; 在奥氏体重结晶的第一温度范围内，在一个或多个热轧道中将板坯还原成板; 在低于所述第一温度范围的第二温度范围内并且高于在冷却期间奥氏体开始转变为铁素体的温度的一个或多个热轧道中进一步减少所述板; 将所述板淬火至合适的淬火停止温度; 并停止所述淬火并允许所述板空气冷却至环境温度。

公开(公告)号：US06224689B1

公开(公告)日：2001-05-01

申请号：US09123859

申请日：1998-07-28

申请人： Jayoung Koo ,  Michael J. Luton ,  Narasimha-Rao V. Bangaru ,  Clifford W. Petersen ,  Hiroshi Tamehiro ,  Hitoshi Asahi ,  Takuya Hara ,  Yoshio Terada

发明人： Jayoung Koo ,  Michael J. Luton ,  Narasimha-Rao V. Bangaru ,  Clifford W. Petersen ,  Hiroshi Tamehiro ,  Hitoshi Asahi ,  Takuya Hara ,  Yoshio Terada

IPC分类号： C22C3812

CPC分类号： C22C38/08 ,  C21D1/19 ,  C21D2211/002 ,  C21D2211/005 ,  C22C38/04 ,  C22C38/12 ,  C22C38/14

摘要： An ultra-high strength essentially boron-free steel having a tensile strength of at least about 900 MPa (130 ksi), a toughness as measured by Charpy V-notch impact test at −40° C. (−40° F.) of at least about 120 joules (90 ft-lbs), and a microstructure comprising predominantly fine-grained lower bainite, fine-grained lath martensite, or mixtures thereof, transformed from substantially unrecrystallized austenite grains and comprising iron and specified weight percentages of the additives: carbon, silicon, manganese, copper, nickel, niobium, vanadium, molybdenum, chromium, titanium, aluminum, calcium, Rare Earth Metals, and magnesium, is prepared by heating a steel slab to a suitable temperature; reducing the slab to form plate in one or more hot rolling passes in a first temperature range in which austenite recrystallizes; further reducing said plate in one or more hot rolling passes in a second temperature range below said first temperature range and above the temperature at which austenite begins to transform to ferrite during cooling; quenching said plate to a suitable Quench Stop Temperature; and stopping said quenching and allowing said plate to air cool to ambient temperature.

摘要翻译： 具有至少约900MPa（130ksi）拉伸强度的超高强度基本上不含硼的钢，在-40℃（-40°F）下通过夏比V-缺口冲击试验测得的韧性 至少约120焦耳（90ft-lbs），以及由基本上未再结晶的奥氏体晶粒转化并且包含铁和特定重量百分比的添加剂的主要包含细粒度的下贝氏体，细粒状板条马氏体或其混合物的显微组织： 通过将钢坯加热到合适的温度来制备碳，硅，锰，铜，镍，铌，钒，钼，铬，钛，​​铝，钙，稀土金属和镁。 在奥氏体重结晶的第一温度范围内，在一个或多个热轧道中将板坯还原成板; 在低于所述第一温度范围的第二温度范围内并且高于在冷却期间奥氏体开始转变为铁素体的温度的一个或多个热轧道中进一步减少所述板; 将所述板淬火至合适的淬火停止温度; 并停止所述淬火并允许所述板空气冷却至环境温度。

公开(公告)号：US5798004A

公开(公告)日：1998-08-25

申请号：US714098

申请日：1997-01-14

申请人： Hiroshi Tamehiro ,  Hitoshi Asahi ,  Takuya Hara ,  Yoshio Terada

发明人： Hiroshi Tamehiro ,  Hitoshi Asahi ,  Takuya Hara ,  Yoshio Terada

IPC分类号： C21D8/02 ,  C22C38/04 ,  C22C38/08 ,  C22C38/48

CPC分类号： C21D8/0226 ,  C22C38/04 ,  C21D2211/002 ,  C21D2211/008 ,  C21D8/0263

摘要： This invention adds elements such as Cu, B, Cr, Ca, V, etc., to a low carbon-high Mn--Ni--Mo-trace Ti type steel, and allows the steel to have a tempered martensite/bainite mixed structure containing at least 60% of tempered martensite transformed from un-recrystallized austenite having a mean austenite grain size (d.gamma.) of not greater than 10 .mu.m as a micro-structure, or a tempered martensite structure containing at least 90% of martensite transformed from un-recrystallized austenite. The present invention further stipulates a P value to the range of 1.9 to 4.0 and thus provides a ultra-high strength steel having a tensile strength of at least 950 MPa (not lower than 100 of the API standard) and excellent in low temperature toughness, HAZ toughness and field weldability in cold districts.

摘要翻译： PCT No.PCT / JP96 / 00155 Sec。 371日期1997年1月14日 102（e）1997年1月14日PCT PCT 1996年1月26日PCT公布。 公开号WO96 / 23083 日期1996年8月1日本发明将诸如Cu，B，Cr，Ca，V等的元素添加到低碳高Mn-Ni-Mo-Trace Ti型钢中，并允许钢具有回火马氏体 或含有至少60％的平均奥氏体晶粒尺寸（dγ）不大于10μm的未再结晶奥氏体作为微结构的回火马氏体的贝氏体混合结构，或包含至少90°的回火马氏体组织 从未再结晶奥氏体转变的马氏体的％。 本发明进一步规定P值在1.9〜4.0的范围内，由此提供抗拉强度为至少950MPa（API标准的100以上），低温韧性优异的超高强度钢， 冷区的HAZ韧性和现场焊接性。

公开(公告)号：US06532995B1

公开(公告)日：2003-03-18

申请号：US09478653

申请日：2000-01-06

申请人： Hitoshi Asahi ,  Hiroshi Tamehiro ,  Takuya Hara ,  Yoshio Terada ,  Shigeru Ohkita ,  Kunio Koyama

发明人： Hitoshi Asahi ,  Hiroshi Tamehiro ,  Takuya Hara ,  Yoshio Terada ,  Shigeru Ohkita ,  Kunio Koyama

IPC分类号： F16L900

CPC分类号： C22C38/12 ,  C22C38/04 ,  C22C38/08 ,  C22C38/44 ,  C22C38/46 ,  C22C38/58 ,  Y10T29/18

摘要： To provide a super-high strength line pipe that is excellent in low temperature toughness, can be field welded easily, and has a tensile strength of at least 900 MPa (exceeding ×100 of the API standard), and a production method thereof. The present invention relates to a super-high strength line pipe produced by shaping a steel plate into a pipe shape and arc welding seam portions, the strength of a base steel portion is 900 to 1,100 MPa and the strength of the weld metal is higher than the base steel strength −100 MPa. In the steel pipe, the Ni content of the weld metal is higher by at least 1% than that of the base steel. The combination of the chemical components of the steel plate with those of the weld metal, for accomplishing these steel pipes by a U&O step is shown concretely. A production method of the steel plate and the welding method for achieving the steel pipe are also described. Furthermore, a method of reducing the strength of the inner surface of the weld metal to restrict cracking at the time of pipe expansion is also shown.

摘要翻译： 为了提供低温韧性优异的超高强度线管，可以容易地进行现场焊接，并且具有至少900MPa（超过API标准的×100）的拉伸强度及其制造方法。 本发明涉及一种通过将钢板成形为管状和电弧焊缝部而制造的超高强度线管，基部钢的强度为900〜1100MPa，焊接金属的强度高于 基钢强度-100MPa。 在钢管中，焊接金属的Ni含量比基体钢高1％以上。 具体地说，钢板的化学成分与焊接金属的化学成分的组合，通过U＆O工序来实现这些钢管。 还描述了钢板的制造方法和用于实现钢管的焊接方法。 此外，还示出了降低焊接金属内表面的强度以限制管膨胀时的开裂的方法。

公开(公告)号：US5755895A

公开(公告)日：1998-05-26

申请号：US718567

申请日：1996-10-10

申请人： Hiroshi Tamehiro ,  Hitoshi Asahi ,  Takuya Hara ,  Yoshio Terada

发明人： Hiroshi Tamehiro ,  Hitoshi Asahi ,  Takuya Hara ,  Yoshio Terada

IPC分类号： C22C38/04 ,  C22C38/44 ,  C22C38/48

CPC分类号： C22C38/04 ,  Y10S148/909

摘要： An ultra-high strength low yield ratio line pipe steel has an excellent HAZ toughness and field weldability and has a tensile strength of at least 950 MPa (exceeding X100 of the API standard). The steel is of a low carbon-high Mn-Ni-Mo-Nb-trace Ti type selectively containing B, Cu, Cr and V, whenever necessary. Its micro-structure comprises a martensite/bainite and ferrite soft/hard two-phase mixed structure having a ferrite fraction of 20 to 90%. This ferrite contains 50 to 1000 of worked ferrite, and the ferrite grain size is not greater than 5 Am. The production of an ultra-high strength low yield ratio line pipe steel (exceeding X100) excellent in low temperature toughness and field weldability becomes possible. As a result, the safety of a pipeline can be remarkably improved, and execution efficiency and transportation efficiency of the pipeline can be drastically improved.

摘要翻译： PCT No.PCT / JP96 / 00157 Sec。 371日期：1996年10月1日 102（e）日期1996年10月1日PCT 1996年1月26日PCT PCT。 第WO96 / 23909号公报 日期1996年8月8日超高强度低屈服比管线钢具有优异的HAZ韧性和现场焊接性，拉伸强度至少为950MPa（超过API标准的X100）。 该钢是选择性含有B，Cu，Cr和V的低碳高Mn-Ni-Mo-Nb-微量Ti型。 其微结构包括铁素体分数为20〜90％的马氏体/贝氏体和铁素体软/硬两相混合结构。 该铁氧体含有50〜1000个加工铁素体，铁素体晶粒尺寸不大于5A。 可以生产出具有优异的低温韧性和现场焊接性的超高强度低屈服比管线钢管（超过X100）。 因此，可以显着提高管道的安全性，可以显着提高管道的执行效率和运输效率。

公开(公告)号：US08974610B2

公开(公告)日：2015-03-10

申请号：US13575051

申请日：2011-02-04

申请人： Taishi Fujishiro ,  Takuya Hara ,  Yoshio Terada ,  Shinya Sakamoto ,  Hitoshi Asahi

发明人： Taishi Fujishiro ,  Takuya Hara ,  Yoshio Terada ,  Shinya Sakamoto ,  Hitoshi Asahi

IPC分类号： C21D9/08 ,  C21D8/10 ,  C22C38/12 ,  C22C38/02 ,  C22C38/04 ,  F16L31/02 ,  B23K35/30 ,  B23K31/02 ,  C21D9/50 ,  C22C38/00 ,  C22C38/14

CPC分类号： B23K35/3053 ,  B23K31/027 ,  B23K2101/06 ,  B23K2103/04 ,  C21D8/105 ,  C21D9/08 ,  C21D9/50 ,  C21D2211/002 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/12 ,  C22C38/14 ,  Y10S148/909

摘要： A high-strength welded steel pipe is obtained by welding a seam weld portion of a steel plate that are formed in a pipe shape. In the high-strength welded steel pipe, a base metal of the steel plate includes, by mass %, C: 0.010% to 0.080%, Si: 0.01% to 0.50%, Mn: 0.50% to 2.00%, S: 0.0001% to 0.0050%, Ti: 0.003% to 0.030%, Mo: 0.05% to 1.00%, B: 0.0003% to 0.0100%, O: 0.0001% to 0.0080%, N: 0.006% to 0.0118%, P: limited to 0.050% or less, Al: limited to 0.008% or less, and the balance of Fe and inevitable impurities, Ceq is 0.30 to 0.53, Pcm is 0.10 to 0.20, [N]−[Ti]/3.4 is less than 0.003, the average grain size of the prior γ grains in heat affected zones in the steel plate is 250 μm or less, and the prior γ grains include bainite and intragranular bainite.

摘要翻译： 通过焊接形成管状的钢板的焊缝部分来获得高强度焊接钢管。 在高强度焊接钢管中，钢板的贱金属以质量％计含有C：0.010〜0.080％，Si：0.01〜0.50％，Mn：0.50〜2.00％，S：0.0001％ 至0.0050％，Ti：0.003％至0.030％，Mo：0.05％至1.00％，B：0.0003％至0.0100％，O：0.0001％至0.0080％，N：0.006％至0.0118％，P：限于0.050％ 以下，Al：0.008％以下，Fe和不可避免的杂质余量Ceq为0.30〜0.53，Pcm为0.10〜0.20，[N] - [Ti] /3.4小于0.003，平均粒径 钢板的热影响区域的现有γ晶粒的尺寸为250μm以下，原来的γ晶粒包括贝氏体和晶粒内贝氏体。

公开(公告)号：US20120291907A1

公开(公告)日：2012-11-22

申请号：US13575051

申请日：2011-02-04

申请人： Taishi Fujishiro ,  Takuya Hara ,  Yoshio Terada ,  Shinya Sakamoto ,  Hitoshi Asahi

发明人： Taishi Fujishiro ,  Takuya Hara ,  Yoshio Terada ,  Shinya Sakamoto ,  Hitoshi Asahi

IPC分类号： F16L9/00 ,  B23K31/02

CPC分类号： B23K35/3053 ,  B23K31/027 ,  B23K2101/06 ,  B23K2103/04 ,  C21D8/105 ,  C21D9/08 ,  C21D9/50 ,  C21D2211/002 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/12 ,  C22C38/14 ,  Y10S148/909

摘要： A high-strength welded steel pipe is obtained by welding a seam weld portion of a steel plate that are formed in a pipe shape. In the high-strength welded steel pipe, a base metal of the steel plate includes, by mass %, C: 0.010% to 0.080%, Si: 0.01% to 0.50%, Mn: 0.50% to 2.00%, S: 0.0001% to 0.0050%, Ti: 0.003% to 0.030%, Mo: 0.05% to 1.00%, B: 0.0003% to 0.0100%, O: 0.0001% to 0.0080%, N: 0.006% to 0.0118%, P: limited to 0.050% or less, Al: limited to 0.008% or less, and the balance of Fe and inevitable impurities, Ceq is 0.30 to 0.53, Pcm is 0.10 to 0.20, [N]—[Ti]/3.4 is less than 0.003, the average grain size of the prior γ grains in heat affected zones in the steel plate is 250 μm or less, and the prior γ grains include bainite and intragranular bainite.

摘要翻译： 通过焊接形成管状的钢板的焊缝部分来获得高强度焊接钢管。 在高强度焊接钢管中，钢板的贱金属以质量％计含有C：0.010〜0.080％，Si：0.01〜0.50％，Mn：0.50〜2.00％，S：0.0001％ 至0.0050％，Ti：0.003％至0.030％，Mo：0.05％至1.00％，B：0.0003％至0.0100％，O：0.0001％至0.0080％，N：0.006％至0.0118％，P：限于0.050％ 以下，Al：0.008％以下，Fe和不可避免的杂质余量Ceq为0.30〜0.53，Pcm为0.10〜0.20，[N] - [Ti] /3.4小于0.003，平均粒径 钢板的热影响区域的现有γ晶粒的尺寸为250μm以下，原来的γ晶粒包括贝氏体和晶粒内贝氏体。

公开(公告)号：US08764918B2

公开(公告)日：2014-07-01

申请号：US12308677

申请日：2007-07-02

申请人： Takuya Hara ,  Hitoshi Asahi ,  Yoshio Terada

发明人： Takuya Hara ,  Hitoshi Asahi ,  Yoshio Terada

IPC分类号： C22C38/00 ,  C21D9/08 ,  C21D8/04 ,  C22C38/04 ,  C22C38/12 ,  C22C38/14

CPC分类号： F16L9/02 ,  B23K35/30 ,  C21D8/02 ,  C21D8/10 ,  C21D9/08 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/16 ,  C22C38/20 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58

摘要： The present invention provides high strength steel pipe for line pipe superior in low temperature toughness suppressed in drop of toughness of the HAZ and a method of production of the same, more particularly high strength steel plate for line pipe used as a material for high strength steel pipe for line pipe and a method of production of the same, in particular high strength steel pipe for line pipe superior in low temperature toughness characterized in that the chemical compositions of the base metal is, by mass %, C: 0.020 to 0.080%, Si: 0.01 to 0.50%, Mo: 0.01 to 0.15%, Al: 0.0005 to 0.030%, and Nb: 0.0001 to 0.030% contained in a range of C+0.25Si+0.1Mo+Al+Nb: 0.100% or less and the mixture of austenite and martensite present along prior austenite grain boundaries of the reheated part of the heat affected zone has a width of 10 μm or less and a length of 50 μm or less.

摘要翻译： 本发明提供了一种耐高温韧性优异的管道管的高强度钢管，其抑制了HAZ的韧性下降及其制造方法，特别是用作高强度钢材料的管线管的高强度钢板 线管用管及其制造方法，特别是低温韧性优异的管线管用高强度钢管，其特征在于，所述贱金属的化学成分以质量％计含有C：0.020〜0.080％， Si：0.01〜0.50％，Mo：0.01〜0.15％，Al：0.0005〜0.030％，Nb：0.0001〜0.030％，C + 0.25Si + 0.1Mo + Al + Nb：0.100％以下， 存在于热影响区域的再加热部分的先前奥氏体晶界上的奥氏体和马氏体的混合物的宽度为10μm以下，长度为50μm以下。

公开(公告)号：US20090025835A1

公开(公告)日：2009-01-29

申请号：US11887885

申请日：2005-04-19

申请人： Takuya Hara ,  Yasuhiro Shinohara ,  Hitoshi Asahi ,  Yoshio Terada

发明人： Takuya Hara ,  Yasuhiro Shinohara ,  Hitoshi Asahi ,  Yoshio Terada

IPC分类号： C21D9/08 ,  C22C38/04 ,  C22C38/08 ,  C22C38/20 ,  C22C38/32 ,  C22C38/44

CPC分类号： C22C38/02 ,  C21D8/0205 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/42 ,  C22C38/44 ,  C22C38/58

摘要： The present invention provides high strength steel plate and high strength welded pipe excellent in ductile fracture characteristic and methods of production of the same, that is, high strength steel plate excellent in ductile fracture characteristic, and high strength welded pipe using that steel plate as a base material, having a tensile strength corresponding to the X100 class of the API standard, containing, by mass %, C: 0.01 to 0.5%, Si: 0.01 to 3%, Mn: 0.1 to 5%, P: 0.03% or less, and S: 0.03% or less and a balance of Fe and unavoidable impurities, having a microstructure comprised of, by area ratio, 1 to 60% of ferrite and the balance of bainite and martensite, having a maximum value of the {100} accumulation degree of the cross-section rotated 20 to 50° from the plate thickness cross-section about the rolling direction as an axis of 3 or less, and having plate thickness parallel cracks measured by ultrasonic flaw detection of less than 1 mm.

摘要翻译： 本发明提供了具有优异的延性断裂特性的高强度钢板和高强度焊接管及其制造方法，即延性断裂特性优异的高强度钢板，以及使用该钢板作为 基材，具有对应于API标准的X100等级的拉伸强度，以质量％计含有C：0.01〜0.5％，Si：0.01〜3％，Mn：0.1〜5％，P：0.03％以下 ，S：0.03％以下，余量为Fe和不可避免的杂质，其微结构由面积比为1〜60％的铁素体和余量的贝氏体和马氏体构成，其最大值为{100} 横截面从作为轴线的轧制方向的板厚横截面旋转20至50°的横截面的累积度为3以下，并且通过超声波探伤小于1mm测量的板厚平行裂纹。