摘要:
Provided are a high-strength hot-dip galvanized steel sheet having excellent formability and a tensile strength of 440 MPa or more and a method for manufacturing the same. A steel sheet has a microstructure containing a ferrite phase having an area fraction of 60% or more, a pearlite phase having an area fraction of 20% to 30%, and a bainite phase having an area fraction of 1% to 5%, the area fraction of a cementite phase present in a grain of the ferrite phase being 5% or less. Upon manufacture, a hot-rolled sheet or a cold-rolled sheet is heated to a temperature of 650° C. or higher at an average heating rate of 10° C./s or more, is held at a temperature of 700° C. to (Ac3-5)° C. for ten seconds or more, is cooled to a temperature of 300° C. to 500° C. at an average cooling rate of 10° C./s to 200° C./s, is held at a temperature of 300° C. to 500° C. for 30 seconds to 300 seconds, and is then hot-dip galvanized.
摘要:
Provided are a high-strength hot-dip galvanized steel sheet having excellent formability and a tensile strength of 440 MPa or more and a method for manufacturing the same. A steel sheet has a microstructure containing a ferrite phase having an area fraction of 60% or more, a pearlite phase having an area fraction of 20% to 30%, and a bainite phase having an area fraction of 1% to 5%, the area fraction of a cementite phase present in a grain of the ferrite phase being 5% or less. Upon manufacture, a hot-rolled sheet or a cold-rolled sheet is heated to a temperature of 650° C. or higher at an average heating rate of 10° C./s or more, is held at a temperature of 700° C. to (Ac3-5)° C. for ten seconds or more, is cooled to a temperature of 300° C. to 500° C. at an average cooling rate of 10° C./s to 200° C./s, is held at a temperature of 300° C. to 500° C. for 30 seconds to 300 seconds, and is then hot-dip galvanized.
摘要:
A steel sheet excellent in FB performance and also excellent in fabrication performance after FB working and a manufacturing method of the same are provided. The steel sheet is a steel sheet having a composition containing from 0.1 to 0.5% of C, not more than 0.5% of Si and from 0.2 to 1.5% of Mn in terms of % by mass, with P and S being adjusted at proper ranges and having a structure having a ferrite having an average grain size of more than 10 μm and less than 20 μm and a cementite present in the ferrite grain having an average particle size of from 0.3 to 1.5 μm. In this way, the steel sheet becomes a steel sheet excellent in FB performance, mold life and performance (side bend elongation) after FB working.
摘要:
The present invention relates to a high strength hot rolled steel sheet consisting of 0.04 to 0.15% C, 1.5% or less Si, 0.5 to 1.6% Mn, 0.04% or less P, 0.005% or less S, 0.04% or less Al, 0.03 to 0.15% Ti, 0.03 to 0.5% Mo, by mass, and balance of Fe and inevitable impurities, and having a microstructure consisting of ferrite containing precipitates, second phase of bainite and/or martensite, and other phase, wherein the percentage of the ferrite containing precipitates is 40 to 95%, and the percentage of the other phase is 5% or less. For example, the high strength hot rolled steel sheet having a thickness of 1.4 mm shows a tensile strength of 780 MPa or higher, an elongation of 22% or higher elongation, and a hole expansion ratio of 60% or higher, thus the steel sheetis suitable for reinforcing members automobile cabin and crash worthiness members of automobile.
摘要:
A high strength galvanized steel sheet having tensile strength of 590MPa or more which is excellent in fatigue property in punching work, and a manufacturing method thereof are provided. The microstructure includes a ferrite phase having an average grain diameter of 15 μm or less and an area fraction of 60% or more and a martensite phase having an area fraction of 5 to 40%, and an amount of one or more kinds of oxide selected from a group consisting of Fe, Si, Mn, Al, P, Nb, and Ti generated on a surface layer portion of the steel sheet within 100 μm in a steel-sheet-side depth direction from a surface of a base steel sheet directly below a galvanized layer is less than 0.060 g/m2 per one-side surface of the steel sheet.
摘要翻译:提供一种拉伸强度为590MPa以上的冲压加工疲劳性优异的高强度镀锌钢板及其制造方法。 微观结构包括平均粒径为15μm以下,面积分率为60%以上的铁素体相,面积分数为5〜40%的马氏体相和选择的一种以上的氧化物的量 从钢基板表面直接在钢板侧深度方向上在钢板表面层上产生的由Fe,Si,Mn,Al,P,Nb,Ti组成的组中, 在镀锌层以下,钢板的单面表面小于0.060g / m 2。
摘要:
A high carbon hot-rolled steel sheet which is a hot-rolled spheroidizing annealed material, including 0.2 to 0.7% C, 2% or less Si, 2% or less Mn, 0.03% or less P, 0.03% or less S, 0.08% or less Sol.Al., and 0.01% or less N, by mass, which contains carbide having a particle size of smaller than 0.5 μm in a content of 15% or less by volume to the total amount of carbide, and the difference between the maximum hardness Hv max and the minimum hardness Hv min, ΔHv (=Hv max−Hv min), in the sheet thickness direction being 10 or smaller.
摘要:
A high carbon cold-rolled steel sheet having both excellent stretch-flange formability and excellent homogeneity of hardness in the sheet thickness direction is provided by a manufacturing method having the steps of: hot-rolling a steel containing 0.2 to 0.7% C by mass at finishing temperatures of (Ar3 transformation point −20° C.) or above to prepare a hot-rolled sheet; cooling the hot-rolled sheet to temperatures of 650° C. or below at cooling rates from 60° C./s or larger to smaller than 120° C./s; coiling the hot-rolled sheet after cooling at coiling temperatures of 600° C. or below; cold-rolling the coiled hot-rolled sheet at rolling reductions of 30% or more to prepare a cold-rolled sheet; and annealing the cold-rolled sheet at annealing temperatures from 600° C. or larger to Ac1 transformation point or lower.
摘要:
A high strength galvanized steel sheet having tensile strength of 590 MPa or more which is excellent in fatigue property in punching work, and a manufacturing method thereof are provided. The microstructure includes a ferrite phase having an average grain diameter of 15 μm or less and an area fraction of 60% or more and a martensite phase having an area fraction of 5 to 40%, and an amount of one or more kinds of oxide selected from a group consisting of Fe, Si, Mn, Al, P, Nb, and Ti generated on a surface layer portion of the steel sheet within 100 μm in a steel-sheet-side depth direction from a surface of a base steel sheet directly below a galvanized layer is less than 0.060 g/m2 per one-side surface of the steel sheet.
摘要翻译:提供了一种拉伸强度为590MPa以上的冲压加工疲劳性优异的高强度镀锌钢板及其制造方法。 微观结构包括平均粒径为15μm以下,面积分率为60%以上的铁素体相,面积分数为5〜40%的马氏体相和选择的一种或多种氧化物的量 从在钢板侧深度方向上从钢基板表面直接在钢板表面层上产生的由Fe,Si,Mn,Al,P,Nb和Ti组成的组中, 在镀锌层以下,钢板的单面表面小于0.060g / m 2。
摘要:
A steel sheet excellent in FB performance-and also excellent in fabrication performance after FB working and a manufacturing method of the same are provided. The steel sheet is a steel sheet having a composition containing from 0.1 to 0.5% of C, not more than 0.5% of Si and from 0.2 to 1.5% of Mn in terms of % by mass, with P and S being adjusted at proper ranges, and having a structure in which a ferrite has an average grain size of from 1 to 10 μm, cementite has a spheroidization ratio of 80% or more, and of the cementite, an amount Sgb of ferrite intergranular cementite which is defined by the following expression (1): Sgb(%)={Son/(Son+Sin)}×100 (wherein Son represents a total occupied area of cementite present on the ferrite grain boundary of the cementite present per unit area; and Snin represents a total occupied area of cementite present in a ferrite grain of the cementite present per unit area) is 40% or more. In this way, the steel sheet becomes a steel sheet excellent in FB performance, mold life and performance after FB working.
摘要:
The present invention relates to a high strength hot rolled steel sheet consisting of 0.04 to 0.15% C, 1.5% or less Si, 0.5 to 1.6% Mn, 0.04% or less P, 0.005% or less S, 0.04% or less Al, 0.03 to 0.15% Ti, 0.03 to 0.5% Mo, by mass, and balance of Fe and inevitable impurities, and having a microstructure consisting of ferrite containing precipitates, second phase of bainite and/or martensite, and other phase, wherein the percentage of the ferrite containing precipitates is 40 to 95%, and the percentage of the other phase is 5% or less. For example, the high strength hot rolled steel sheet having a thickness of 1.4 mm shows a tensile strength of 780 MPa or higher, an elongation of 22% or higher elongation, and a hole expansion ratio of 60% or higher, thus the steel sheet is suitable for reinforcing members automobile cabin and crash worthiness members of automobile.