摘要:
A low yield ratio and high-strength hot rolled steel sheet having a composition containing, on a mass percent basis, 0.03% to 0.10% C, 0.10% to 0.50% Si, 1.4% to 2.2% Mn, 0.005 % to 0.10% Al, 0.02% to 0.10% Nb, 0.001% to 0.030% Ti, 0.05% to 0.50% Mo, 0.05% to 0.50% Cr, and 0.01% to 0.50% Ni, in which Moeq preferably satisfies the range of 1.4% to 2.2%; and a microstructure including a main phase that contains bainitic ferrite having an average grain size of 10 μm or less and a secondary phase that contains massive martensite having an aspect ratio of less than 5.0 in an area ratio of 1.4% to 15%.
摘要:
A hot rolled steel sheet for a square column for building structural members, the hot rolled steel sheet having a composition of, in terms of % by mass, C: 0.07 to 0.18%, Mn: 0.3 to 1.5%, P: 0.03% or less, S: 0.015% or less, N: 0.006% or less, Al: 0.01 to 0.06%, and the balance being Fe and unavoidable impurities, and having a microstructure that includes a primary phase constituted of ferrite and a second phase constituted of pearlite or pearlite and bainite, wherein a second phase frequency defined by equation (1) below is 0.20 to 0.42 and a mean crystal grain diameter of the primary phase and the second phase together is 7 to 15 μm Second phase frequency=(Number of second phase grains intersecting line segments of particular length)/(Number of primary phase grains and second phase grains intersecting line segments of particular length) (1).
摘要:
A hot rolled steel sheet for a square column for building structural members, the hot rolled steel sheet having a composition of, in terms of % by mass, C: 0.07 to 0.18%, Mn: 0.3to 1.5%, P: 0.03% or less, S: 0.015% or less, N: 0.006% or less, Al: 0.01 to 0.06%, and the balance being Fe and unavoidable impurities, and having a microstructure that includes a primary phase constituted of ferrite and a second phase constituted of pearlite or pearlite and bainite, wherein a second phase frequency defined by equation (1) below is 0.20 to 0.42 and a mean crystal grain diameter of the primary phase and the second phase together is 7 to 15 μm Second phase frequency=(Number of second phase grains intersecting line segments of particular length)/(Number of primary phase grains and second phase grains intersecting line segments of particular length) (1).
摘要:
A hot-rolled steel sheet for high-strength ERW pipes contains about 0.02% to about 0.06% C; about 0.05% to about 0.50% Si; about 0.5% to about 1.5% Mn; about 0.010% or less P; about 0.0010% or less S; about 0.01% to about 0.10% Al; about 0.01% to about 0.10% Nb; about 0.001% to about 0.025% Ti; about 0.001% to about 0.005% Ca; about 0.003% or less 0; and about 0.005% or less N, and at least one element selected from the group consisting of about 0.01% to about 0.10% V; about 0.01% to about 0.50% Cu; about 0.01% to about 0.50% Ni; and about 0.01% to about 0.50% Mo on the basis of mass. The group of C, Si, Mn, Cu, Ni, Mo, and V and the group of Ca, 0, and S satisfy specific relationships, and the microstructure of the steel sheet is composed of about 95% by volume or more bainitic ferrite.
摘要:
A hot-rolled steel sheet for high-strength ERW pipes contains about 0.02% to about 0.06% C; about 0.05% to about 0.50% Si; about 0.5% to about 1.5% Mn; about 0.010% or less P; about 0.0010% or less S; about 0.01% to about 0.10% Al; about 0.01% to about 0.10% Nb; about 0.001% to about 0.025% Ti; about 0.001% to about 0.005% Ca; about 0.003% or less 0; and about 0.005% or less N, and at least one element selected from the group consisting of about 0.01% to about 0.10% V; about 0.01% to about 0.50% Cu; about 0.01% to about 0.50% Ni; and about 0.01% to about 0.50% Mo on the basis of mass. The group of C, Si, Mn, Cu, Ni, Mo, and V and the group of Ca, 0, and S satisfy specific relationships, and the microstructure of the steel sheet is composed of about 95% by volume or more bainitic ferrite.
摘要:
A high-tensile-strength hot-rolled steel sheet is provided having a composition which contains 0.02 to 0.08% C, 0.01 to 0.10% Nb, 0.001 to 0.05% Ti and Fe and unavoidable impurities as a balance, wherein the steel sheet contains C, Ti and Nb in such a manner that (Ti+(Nb/2))/C
摘要翻译:本发明提供一种组成为含有0.02〜0.08%C,0.01〜0.10%Nb,0.001〜0.05%Ti,Fe和余量的不可避免的杂质的高强度热轧钢板,其中钢板含有C ,Ti和Nb以满足(Ti +(Nb / 2))/ C <4的方式,并且钢板具有这样的结构,其中在距离片材表面1mm的位置处的结构的主相 厚度方向选自铁素体相,回火马氏体和铁素体相和回火马氏体的混合组织中的一种,板厚中心位置处的结构的主相由铁素体相形成,差异 在板厚方向上距离表面1mm处的第二相的结构部分(体积%)和板厚中心位置处的二次相的结构分数(体积%)之间的差为2% 或更少。
摘要:
A hot-rolled steel strip having superior low temperature toughness and weldability, which is suitably used as a starting material for high strength electric resistance welding pipe, is provided at a low cost without constructing new production facilities and increasing cost. The hot-rolled steel strip is low carbon steel containing at least one of about 0.5.% or less of Cu, about 0.5% or less of Ni, and about 0.5% or less of Mo, wherein Pcm represented by the following equation (1) is 0.17 or less: Pcm=(% C)+(% Si)/30+((% Mn)+(% Cu))/20+(% Ni)/60+(% Mo)/7+(% V)/10 Equation (1), (where (% M) indicates the content of element M on a mass percent basis), and the balance includes Fe and incidental impurities. In addition, in the entire microstructure, the ratio of bainitic ferrite, which is a primary phase, is controlled to be about 95 percent by volume or more.
摘要:
A high-tensile-strength hot-rolled steel sheet is provided having a composition which contains 0.02 to 0.08% C, 0.01 to 0.10% Nb, 0.001 to 0.05% Ti and Fe and unavoidable impurities as a balance, wherein the steel sheet contains C, Ti and Nb in such a manner that (Ti+(Nb/2))/C
摘要翻译:本发明提供一种组成为含有0.02〜0.08%C,0.01〜0.10%Nb,0.001〜0.05%Ti,Fe和余量的不可避免的杂质的高强度热轧钢板,其中钢板含有C ,Ti和Nb以满足(Ti +(Nb / 2))/ C <4的方式,并且钢板具有这样的结构,其中在距离片材表面1mm的位置处的结构的主相 厚度方向选自铁素体相,回火马氏体和铁素体相和回火马氏体的混合组织中的一种,板厚中心位置处的结构的主相由铁素体相形成,差异 在板厚方向上距离表面1mm处的第二相的结构部分(体积%)和板厚中心位置处的二次相的结构分数(体积%)之间的差为2% 或更少。
摘要:
A thick-walled high-strength hot rolled steel sheet has a high tensile strength TS of 521 MPa or more and excellent low-temperature toughness. The steel material forming the sheet contains 0.02%-0.08% C, 0.01%-0.10% Nb, and 0.001%-0.05% Ti and is heated; C, Ti, and Nb satisfies (Ti+(Nb/2))/C
摘要翻译:厚壁高强度热轧钢板的拉伸强度TS为521MPa以上,低温韧性优异。 形成片材的钢材含有0.02%-0.08%C,0.01%-0.10%Nb和0.001%-0.05%Ti,并加热; C,Ti和Nb满足(Ti +(Nb / 2))/ C <4。
摘要:
An object of the present invention is to provide a cold-rolled steel sheet and an alloyed hot-dip galvanized steel sheet in which tensile strength is effectively increased by press forming and heat treatment while maintaining excellent deep drawability in press forming. Specifically, a steel composition contains less than 0.01% of C, 0.005 to 1.0% of Si, 0.01 to 1.0% of Mn, 0.005 to 0.050% of Nb, 0.005 to 0.030% of Al, 0.005 to 0.040% of N, 0.0005 to 0.0015% of B, 0.05% or less of P, and 0.01% or less of S, the balance substantially composed of Fe, in which the following equations (1) and (2) are satisfied: N %≧0.0015+14/93·Nb %+14/27·Al %+14/11·B % (1) C %≦(12/93)·Nb %. (2)