公开(公告)号：US20080156400A1

公开(公告)日：2008-07-03

申请号：US12073324

申请日：2008-03-04

申请人： Takashi Nakashima ,  Kaori Kawano ,  Masaaki Igarashi

发明人： Takashi Nakashima ,  Kaori Kawano ,  Masaaki Igarashi

IPC分类号： C22C38/22

CPC分类号： C21C7/0006 ,  C21C7/06 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/22

摘要： According to a low alloy steel of the present invention, compositional elements thereof are limited, and a metal structure thereof comprises bainite or martensite. Further, a proper amounts of Nd inclusions are formed by appropriately selecting timings of deoxidation and Nd addition in melting a steel. Consequently, compatibility between high-temperature creep strength and long-term creep ductility, which is hardly established in conventional steels, can be achieved even in hostile conditions. Accordingly, the low alloy steel of the present invention can be widely applied as the material for the heat-resistant structural member used for a long time under the high-temperature and high-pressure conditions such as power plant boilers, turbines, and nuclear power plants.

摘要翻译： 根据本发明的低合金钢，其组成元素受到限制，其金属结构包括贝氏体或马氏体。 此外，通过在钢中熔融时适当选择脱氧和Nd添加的定时，形成适量的Nd夹杂物。 因此，即使在恶劣的条件下，也可以实现在常规钢中难以确定的高温蠕变强度与长期蠕变延展性之间的相容性。 因此，本发明的低合金钢可以广泛地用作在高温高压条件下长时间使用的耐火构件的材料，例如发电厂锅炉，涡轮机和核能 植物。

公开(公告)号：US07935303B2

公开(公告)日：2011-05-03

申请号：US12073324

申请日：2008-03-04

申请人： Takashi Nakashima ,  Kaori Kawano ,  Masaaki Igarashi

发明人： Takashi Nakashima ,  Kaori Kawano ,  Masaaki Igarashi

IPC分类号： C22C38/00 ,  C22C38/22

CPC分类号： C21C7/0006 ,  C21C7/06 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/22

摘要： According to a low alloy steel of the present invention, compositional elements thereof are limited, and a metal structure thereof comprises bainite or martensite. Further, proper amounts of Nd inclusions are formed by appropriately selecting timings of deoxidation and Nd addition in melting a steel. Consequently, compatibility between high-temperature creep strength and long-term creep ductility, which is hardly established in conventional steels, can be achieved even in hostile conditions. Accordingly, the low alloy steel of the present invention can be widely applied as the material for the heat-resistant structural member used for a long time under the high-temperature and high-pressure conditions such as power plant boilers, turbines, and nuclear power plants.

摘要翻译： 根据本发明的低合金钢，其组成元素受到限制，其金属结构包括贝氏体或马氏体。 此外，通过在钢中熔融时适当选择脱氧和Nd添加的定时，形成适量的Nd夹杂物。 因此，即使在恶劣的条件下，也可以实现在常规钢中难以确定的高温蠕变强度与长期蠕变延展性之间的相容性。 因此，本发明的低合金钢可以广泛地用作在高温高压条件下长时间使用的耐火构件的材料，例如发电厂锅炉，涡轮机和核能 植物。

公开(公告)号：US08293169B2

公开(公告)日：2012-10-23

申请号：US13070689

申请日：2011-03-24

申请人： Hiroyuki Semba ,  Atsuro Iseda ,  Hiroyuki Hirata ,  Kaori Kawano ,  Masaaki Igarashi ,  Osamu Miyahara

发明人： Hiroyuki Semba ,  Atsuro Iseda ,  Hiroyuki Hirata ,  Kaori Kawano ,  Masaaki Igarashi ,  Osamu Miyahara

IPC分类号： C22C19/05

CPC分类号： C22C19/055 ,  C22C19/056

摘要： A high strength, ductile, and tough Ni-base heat resistant alloy comprises by mass percent, C: 0.1% or less, Si: 1% or less, Mn: 1% or less, Cr: not less than 15% to less than 28%, Fe: 15% or less, W: more than 5% to not more than 20%, Al: more than 0.5% to not more than 2%, Ti: more than 0.5% to not more than 2%, Nd: 0.001 to 0.1% and B: 0.0005 to 0.01%, with the balance being Ni and impurities. Impurity contents of P, S, Sn, Pb, Sb, Zn and As are P: 0.03% or less, S: 0.01% or less, Sn: 0.020% or less, Pb: 0.010% or less, Sb: 0.005% or less, Zn: 0.005% or less and As: 0.005% or less, and formulas of [0.015≦Nd+13.4×B≦0.13], [Sn+Pb≦0.025] and [Sb+Zn +As≦0.010] are met.

摘要翻译： 高强度，延性和韧性的Ni基耐热合金，以质量％计，C：0.1％以下，Si：1％以下，Mn：1％以下，Cr：15％以上，小于 28％，Fe：15％以下，W：5％以上20％以下，Al：0.5％以上2％以下，Ti：0.5％以上且2％以下，Nd ：0.001〜0.1％，B：0.0005〜0.01％，余量为Ni和杂质。 P，S，Sn，Pb，Sb，Zn和As的杂质含量P：0.03％以下，S：0.01％以下，Sn：0.020％以下，Pb：0.010％以下，Sb：0.005％ 较少，Zn：0.005％以下，As：0.005％以下，[0.015＆nlE; Nd + 13.4×B＆nlE; 0.13]，[Sn + Pb＆nlE; 0.025]和[Sb + Zn + As＆nlE; 0.025] 见面

公开(公告)号：US20080050265A1

公开(公告)日：2008-02-28

申请号：US11907575

申请日：2007-10-15

申请人： Masaaki Igarashi ,  Kaori Kawano

发明人： Masaaki Igarashi ,  Kaori Kawano

IPC分类号： C22C38/32

CPC分类号： C22C38/22 ,  C22C38/02 ,  C22C38/04 ,  C22C38/24

摘要： A low alloy steel for a heat-resisting structural member being improved in long time creep ductility at high temperatures and temper softening resistance, characterized by comprising, by mass percent, C: 0.03 to 0.10%, Si: not more than 0.30%, Mn: not more than 1.0%, Cr: more than 1.5% to not more than 2.5%, Mo: 0.01 to 1.0%, V: 0.04 to 0.30%, Nb: 0.001 to 0.10%, Ti: 0.001 to 0.020%, B: 0.0001 to 0.020%, Al: 0.001 to 0.01% and Nd: 0.0001 to 0.050%, with the balance being Fe and impurities, wherein the content of P is not more than 0.020%, the content of S is not more than 0.003%, the content of N is less than 0.0050% and the content of O (oxygen) is not more than 0.0050% among the impurities, in which the value of BSO represented by the following formula (1) is 0.0001 to 0.010: BSO=B−(11/14)N−(11/32)S−(11/16)O  (1), wherein each element symbol in the formula (1) represents the content (by mass %) of the element concerned. The steel may further contain one or more element selected from among W, Cu, Ni, Co, Mg, Ca, La, Ce, Y, Sm and Pr.

摘要翻译： 用于耐热结构件的低合金钢在高温下的长时间蠕变延展性和回火软化性得到改善，其特征在于以质量％计含有C：0.03至0.10％，Si：不大于0.30％，Mn ：不大于1.0％，Cr：大于1.5％至不大于2.5％，Mo：0.01至1.0％，V：0.04至0.30％，Nb：0.001至0.10％，Ti：0.001至0.020％，B： 0.0001〜0.020％，Al：0.001〜0.01％，Nd：0.0001〜0.050％，余量为Fe和杂质，其中P含量不大于0.020％，S含量不大于0.003％ 在下述式（1）表示的BSO值为0.0001〜0.010的<！ - SIPO - >杂质中，N的含量小于0.0050％，O（氧）的含量为0.0050％以下。 line-formula description =“In-line Formulas”end =“lead”？> BSO = B-（11/14）N-（11/32）S-（11/16）O（1），< line-formula description =“In-line Formulas”end =“tail”？>其中式（1）中的每个元素符号 代表有关要素的内容（质量百分比）。 钢可以进一步含有选自W，Cu，Ni，Co，Mg，Ca，La，Ce，Y，Sm和Pr中的一种或多种元素。

公开(公告)号：US09970073B2

公开(公告)日：2018-05-15

申请号：US13879074

申请日：2010-10-18

申请人： Kaori Kawano ,  Yasuaki Tanaka ,  Toshiro Tomida

发明人： Kaori Kawano ,  Yasuaki Tanaka ,  Toshiro Tomida

IPC分类号： C21D8/02 ,  C21D8/04 ,  C21D9/46 ,  C21D9/48 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/38 ,  C23C2/02 ,  C23C2/28 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28

CPC分类号： C21D8/0221 ,  C21D8/04 ,  C21D8/0426 ,  C21D8/0436 ,  C21D8/0463 ,  C21D9/46 ,  C21D9/48 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/001 ,  C22C38/02 ,  C22C38/06 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/38 ,  C23C2/02 ,  C23C2/28

摘要： A multi-phase hot-rolled steel sheet has a metallurgical structure having a main phase of ferrite with an average grain diameter of at most 3.0 μm and a second phase including at least one of martensite, bainite, and austenite. In the surface layer, the average grain diameter of the second phase is at most 2.0 μm, the difference (ΔnHav) between the average nanohardness of the main phase (nHαav) and the average nanohardness of the second phase (nH2nd av) is 6.0-10.0 GPa, the difference (ΔσnH) of the standard deviation of the nanohardness of the second phase from the standard deviation of the nanohardness of the main phase is at most 1.5 GPa, and in the central portion, the difference (ΔnHav) between the average nanohardnesses is at least 3.5 GPa to at most 6.0 GPa and the difference (ΔσnH) between the standard deviations of the nanohardnesses is at least 1.5 GPa.

公开(公告)号：US20130098515A1

公开(公告)日：2013-04-25

申请号：US13643696

申请日：2011-04-07

申请人： Yasuaki Tanaka ,  Toshiro Tomida ,  Kaori Kawano

发明人： Yasuaki Tanaka ,  Toshiro Tomida ,  Kaori Kawano

IPC分类号： C22C38/58 ,  C22C38/00 ,  C22C38/38 ,  C22C38/04 ,  C22C38/50 ,  C22C38/28 ,  C22C38/24 ,  C22C38/22 ,  C22C38/20 ,  C22C38/40 ,  C21D8/02 ,  C22C38/02

CPC分类号： C22C38/58 ,  C21D6/005 ,  C21D8/02 ,  C21D8/0226 ,  C21D9/46 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/001 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/20 ,  C22C38/22 ,  C22C38/24 ,  C22C38/28 ,  C22C38/38 ,  C22C38/40 ,  C22C38/50

摘要： A multi-phase hot-rolled steel sheet having improved strength in an intermediate strain rate region has a chemical composition comprising, in mass percent, C: 0.07-0.2%, Si+Al: 0.3-1.5%, Mn: 1.0-3.0%, P: at most 0.02%, S: at most 0.005%, Cr: 0.1-0.5%, N: 0.001-0.008%, at least one of Ti: 0.002-0.05% and Nb: 0.002-0.05%, and a remainder of Fe and impurities. The area fraction of ferrite is 7-35%, the grain diameter of ferrite is in the range of 0.5-3.0 μm, and the nanohardness of ferrite is in the range of 3.5-4.5 GPa. A second phase which is the remainder other than ferrite contains martensite and bainitic ferrite and/or bainite. The average nanohardness of the second phase is 5-12 GPa, and the second phase contains a high-hardness phase of 8-12 GPa with an area fraction of 5-35% based on the overall structure.

摘要翻译： 具有中间变形率区域的强度提高的多相热轧钢板具有质量％C：0.07〜0.2％，Si + Al：0.3〜1.5％，Mn：1.0〜3.0％的化学成分， ，P：0.02％以下，S：0.005％以下，Cr：0.1-0.5％，N：0.001-0.008％，Ti：0.002〜0.05％，Nb：0.002〜0.05％中的至少一种，余量 的铁和杂质。 铁素体的面积率为7-35％，铁素体的晶粒直径在0.5-3.0μm的范围内，铁素体的纳米硬度在3.5-4.5GPa的范围内。 作为铁素体以外的剩余部分的第二相包含马氏体和贝氏体铁素体和/或贝氏体。 第二相的平均纳米硬度为5-12GPa，第二相包含8-12GPa的高硬度相，基于总体结构的面积分数为5-35％。

公开(公告)号：US08313591B2

公开(公告)日：2012-11-20

申请号：US12647028

申请日：2009-12-24

申请人： Hiroyuki Hirata ,  Atsuro Iseda ,  Hirokazu Okada ,  Hiroyuki Semba ,  Kaori Kawano ,  Osamu Miyahara

发明人： Hiroyuki Hirata ,  Atsuro Iseda ,  Hirokazu Okada ,  Hiroyuki Semba ,  Kaori Kawano ,  Osamu Miyahara

IPC分类号： C22C30/00 ,  C22C19/05

CPC分类号： C22C38/44 ,  C21D6/001 ,  C21D6/002 ,  C21D6/004 ,  C22C38/001 ,  C22C38/002 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  F22B37/04

摘要： An austenitic heat resistant alloy, which contains, by mass percent, C≦0.15%, Si≦2%, Mn≦3%, Ni: 40 to 80%, Cr: 15 to 40%, W and Mo: 1 to 15% in total content, Ti≦3%, Al≦3%, N≦0.03%, O≦0.03%, with the balance being Fe and impurities, and among the impurities P≦0.04%, S≦0.03%, Sn≦0.1%, As≦0.01%, Zn≦0.01%, Pb≦0.01% and Sb≦0.01%, and satisfies the conditions [P1=S+{(P+Sn)/2}+{(As+Zn+Pb+Sb)/5}≦0.050], [0.2≦P2=Ti+2Al≦7.5−10×P1], [P2≦9.0−100×O] and [N≦0.002×P2+0.019] can prevent both the liquation crack in the HAZ and the brittle crack in the HAZ and also can prevent defects due to welding fabricability, which occur during welding fabrication, and moreover has excellent creep strength at high temperatures. Therefore, the alloy can be used suitably as a material for constructing high temperature machines and equipment, such as power generating boilers, plants for the chemical industry and so on. The ally may contain a specific amount or amounts of one or more elements selected from Co, B, Ta, Hf, Nb, Zr, Ca, Mg, Y, La, Ce and Nd.

摘要翻译： 一种奥氏体耐热合金，以质量％计含有0.15％，Si＆NlE; 2％，Mn＆NlE; 3％，Ni：40〜80％，Cr：15〜40％，W和Mo：1〜15％ 在总含量中，Ti＆NlE; 3％，Al＆NlE; 3％，N＆amp; NlE; 0.03％，O＆NlE; 0.03％，余量为Fe和杂质，杂质P＆lt; L; 0.04％，S＆NlE; 0.03％，Sn＆ ，As / nlE; 0.01％，Zn和nlE; 0.01％，Pb和nlE; 0.01％和Sb＆nlE; 0.01％，满足条件[P1 = S + {（P + Sn）/ 2} + {（As + Zn + Pb + Sb）/ 5}＆nlE; 0.050]，[0.2＆nlE; P2 = Ti + 2Al＆nlE; 7.5-10×P1]，[P2＆nlE; 9.0-100×O]和[N＆lt; lE; 0.002×P2 + 0.019]可以防止液化裂纹 HAZ和HAZ中的脆性裂纹，并且还可以防止在焊接制造期间发生的焊接可制造性的缺陷，并且还在高温下具有优异的蠕变强度。 因此，该合金可以适当地用作构成发电锅炉，化工工业用等的高温机器和设备的材料。 盟友可以含有一定量或数量的选自Co，B，Ta，Hf，Nb，Zr，Ca，Mg，Y，La，Ce和Nd中的一种或多种元素。

公开(公告)号：US07927433B2

公开(公告)日：2011-04-19

申请号：US12768216

申请日：2010-04-27

申请人： Toshirou Tomida ,  Norio Imai ,  Mitsuru Yoshida ,  Kaori Kawano ,  Masayuki Wakita ,  Tamotsu Toki ,  Masanori Yasuyama ,  Hitomi Nishibata

发明人： Toshirou Tomida ,  Norio Imai ,  Mitsuru Yoshida ,  Kaori Kawano ,  Masayuki Wakita ,  Tamotsu Toki ,  Masanori Yasuyama ,  Hitomi Nishibata

IPC分类号： C22C38/00 ,  C21D8/02 ,  C21D8/04

CPC分类号： C23C2/40 ,  B32B15/012 ,  B32B15/013 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0263 ,  C21D8/0405 ,  C21D8/0463 ,  C21D9/46 ,  C21D9/50 ,  C21D2201/03 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/009 ,  C22C18/04 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C23C2/06 ,  C23C2/28

摘要： A cold-rolled steel sheet of carbon steel or low-alloy steel comprising C: 0.01 to 0.25% by mass with a ferrite main phase is has an average ferrite crystal grain diameter D (μm) at the depth of ¼ of the sheet thickness from the steel sheet surface satisfying formulas (5,6) and the increase rate X (μm/min) in average ferrite crystal grain diameter at 700° C. at the depth of ¼ of the sheet thickness from the steel sheet surface and D (μm) satisfying formula (3): 1.2≦D≦9.3  (5) D≦5.0−2.0·Cr+5000/(5+350·C+40·Mn)2  (6) D·X≦0.1  (3) and, at said ¼ inch depth, the area percentage of ferrite crystal grains the crystal grain diameter d (μm) of which satisfying formula (4) is at least 80%: D/3≦d≦3D  (4) wherein C, Cr and Mn represent mass % of the respective elements in the steel.

摘要翻译： 含铁素体相的C：0.01〜0.25质量％的碳素钢或低合金钢的冷轧钢板的平均铁素体晶粒直径D（μm）为 钢板表面满足式（5,6）的平均铁素体晶粒直径的增加率X（μm/ min），钢板表面的厚度¼的D值（μm） ）满足式（3）：1.2＆nlE; D＆nlE; 9.3（5）D＆nlE; 5.0-2.0·Cr + 5000 /（5 + 350·C + 40·Mn）2（6）D·X＆ 在所述¼英寸深度处，铁素体晶粒的满足公式（4）的晶粒直径d（μm）的面积百分比为至少80％：D / 3＆nlE; d＆nlE; 3D（4）其中C，Cr和 Mn表示钢中各元素的质量％。

公开(公告)号：US07879164B2

公开(公告)日：2011-02-01

申请号：US12768253

申请日：2010-04-27

申请人： Toshirou Tomida ,  Norio Imai ,  Mitsuru Yoshida ,  Kaori Kawano ,  Masayuki Wakita ,  Tamotsu Toki ,  Masanori Yasuyama ,  Hitomi Nishibata

发明人： Toshirou Tomida ,  Norio Imai ,  Mitsuru Yoshida ,  Kaori Kawano ,  Masayuki Wakita ,  Tamotsu Toki ,  Masanori Yasuyama ,  Hitomi Nishibata

IPC分类号： C21D8/02 ,  C21D9/46

CPC分类号： C23C2/40 ,  B32B15/012 ,  B32B15/013 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0263 ,  C21D8/0405 ,  C21D8/0463 ,  C21D9/46 ,  C21D9/50 ,  C21D2201/03 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/009 ,  C22C18/04 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C23C2/06 ,  C23C2/28

摘要： A steel sheet excellent in mechanical strength, workability and thermal stability and suited for use as a raw material in such fields of manufacturing automobiles, household electric appliances, machine structures, and of constructing buildings, and a manufacturing method thereof is provided. The steel sheet is a hot-rolled steel sheet of a carbon steel or low-alloy steel, the main phase of which is ferrite, and is characterized in that the average ferrite crystal grain diameter D(μm) at the depth of ¼ of the sheet thickness from the steel sheet surface satisfies the relations respectively defined by formulas (1) and (2) given below and the increase rate X (μm/min) in average ferrite crystal grain diameter at 700° C. at the depth of ¼ of the sheet thickness from the steel sheet surface and said average crystal grain diameter D(μm) satisfy the relation defined by the formula (3) given below: 1.2≦D≦7  formula (1) D≦2.7+5000/(5+350·C+40·Mn)2  formula (2) D·X≦0.1  formula (3) wherein C and Mn represent the content (in % by mass) of the respective elements in the steel.

摘要翻译： 本发明提供一种机械强度，加工性，热稳定性优异且适用于制造汽车，家用电器，机器结构，建筑物等领域的原料的钢板及其制造方法。 该钢板是碳素钢或低合金钢的热轧钢板，其主相是铁素体，其特征在于，深度为1/4的平均铁素体晶粒直径D（μm） 从钢板表面的板厚满足下述式（1）和（2）所定义的关系，并且在700℃的平均铁素体晶粒直径的增加速度X（μm/ min）在深度为1/4 钢板表面的平均厚度和所述平均晶粒直径D（μm）满足以下公式（3）所定义的关系：1.2＆nlE; D＆nlE; 7式（1）D＆nlE; 2.7 + 5000 /（5+ 350·C + 40·Mn）2式（2）D·X＆nlE; 0.1式（3）其中，C和Mn表示钢中各元素的含量（质量％）。

公开(公告)号：US20080202639A1

公开(公告)日：2008-08-28

申请号：US12068045

申请日：2008-02-01

申请人： Toshirou Tomida ,  Norio Imai ,  Mitsuru Yoshida ,  Kaori Kawano ,  Masayuki Wakita ,  Tamotsu Toki ,  Masanori Yasuyama ,  Hitomi Nishibata

发明人： Toshirou Tomida ,  Norio Imai ,  Mitsuru Yoshida ,  Kaori Kawano ,  Masayuki Wakita ,  Tamotsu Toki ,  Masanori Yasuyama ,  Hitomi Nishibata

IPC分类号： C21D8/04 ,  C22C38/04 ,  C21D11/00 ,  C22C38/18

CPC分类号： C23C2/40 ,  B32B15/012 ,  B32B15/013 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0263 ,  C21D8/0405 ,  C21D8/0463 ,  C21D9/46 ,  C21D9/50 ,  C21D2201/03 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/009 ,  C22C18/04 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C23C2/06 ,  C23C2/28

摘要： A steel sheet excellent in mechanical strength, workability and thermal stability and suited for use as a raw material in such fields of manufacturing automobiles, household electric appliances and machine structures and of constructing buildings, and a manufacturing method thereof. are provided.The steel sheet is a hot-rolled steel sheet of carbon steel or low-alloy steel, the main phase of which is ferrite, and is characterized in that the average ferrite crystal grain diameter D (μm) at the depth of ¼ of the sheet thickness from the steel sheet surface satisfies the relations respectively defined by the formulas (1) and (2) given below and the increase rate X (μm/min) in average ferrite crystal grain diameter at 700° C. at the depth of ¼ of the sheet thickness from the steel sheet surface and said average crystal grain diameter D (μm) satisfy the relation defined by the formula (3) given below: 1.2≦D≦7   formula (1) D≦2.7+5000/(5+350·C+40·Mn)2   formula (2) D·X≦0.1   formula (3) wherein C and Mn represent the contents (in % by mass) of the respective elements in the steel.

摘要翻译： 机械强度，加工性，热稳定性优异的钢板，适用于制造汽车，家用电器和机器结构以及建筑物的领域的原材料及其制造方法。 被提供。 钢板是碳素钢或低合金钢的热轧钢板，其主相是铁素体，其特征在于，在片材的1/4深度处的平均铁素体晶粒直径D（母体） 从钢板表面的厚度满足下面给出的式（1）和（2）所定义的关系，并且在700℃的平均铁素体晶粒直径的增加速率X（mum / min）在深度为1/4 来自钢板表面的板厚和所述平均晶粒直径D（母）满足以下给出的公式（3）所定义的关系：<？in-line-formula description =“In-line Formulas”end =“lead “？> 1.2 <= D <= 7公式（1）<？in-line-formula description =”In-line Formulas“end =”tail“？> <？in-line-formula description =”在线公式 “end =”lead“？> D <= 2.7 + 5000 /（5 + 350.C + 40.Mn）2式（2）<？in-line-formula description =”In- 行公式“end =”tail“？> <？in-line-formula description =”In-line Formulas“end =”lea d“？> DX <= 0.1式（3）<？in-line-formula description =”In-line formula“end =”tail“？>其中C和Mn表示各自的内容（以质量％计） 钢中的元素。