TH57180B - Cold rolled steel sheet with excellent formability, shape retention ability, and surface appearance and method for producing cold rolled steel sheet. - Google Patents

Abstract

DC60 (26/04/59) in low carbon steel, cold rolled steel sheet. And methods for the production of rolled steel sheets The evening will be prepared. Cold rolled steel sheets conform to both workability and shape retention capacity; Can be brought through pulling, bending, and stretching; Will be able to ensure the desired shape for large components; There will be a high flatness; To be free from Appearance defects; And they excel in formability, shape retention, and surface appearance. Cold rolled steel sheet has a C composition of 0.030% to 0.060%, Si 0.05% or less, Mn 0.1% to 0.3%, P 0.05% or less, S 0.02% or less, Al 0.02% to 0.10%. , And N 0.005% or less on a mass basis, the rest are iron and avoided impurities. Its Langford value is 0.7 to 1.4 in the rolling direction and the direction perpendicular to the direction of the rolling. The anisotropy in the ((delta) r) plane of its Langford values corresponds to the inequality. -0.2 (less than or equal to) ((delta) r) (less than or equal to) 0.2 Its average yield strength will be 230 Mpa or less, and its mean elongation will be 40% or more in three directions.

Claims (1)

Claims (total) which will not appear on the advertisement page :Edit 26/4/2016 1. 1.Cold-rolled steel plate with alloy C of 0.030% to 0.060%,Si0.05% or less. than, Mn0.1% to 0.3%, P0.05% or less, S0.02% or less, Al0.02% to 0.10%, and N 0.005% or less on a mass basis, the remainder is Iron and inevitable impurities, where its mean rake strength (YSm) is 230 megapascals (MPa) or less, as determined by the following equation (a); Its average elongation (Elm) will be 40% or more, as determined by the following equation (b); Its langford value is 0.7 to 1.4 in the rolling direction and the direction perpendicular to the direction of rolling; the anisotropy in the plane (?r) of the langford value of it will corresponds to the inequality -0.2?(?r)?0.2 as defined by the following equation (c); and yield elongation of cold-rolled steel plates being maintained at 170 °C for 60 min will be 2% or less in the direction of rolling, the direction of 45 degrees to the direction of rolling, and the direction perpendicular to Iron direction: YSm=(YSL+2YSD+YSc/4 (a) Elm=(ElL+2ElD+Elc/4 (b) ((?r)=(rL-2rD+rc)/2 (c) where where YSm is the average yield strength, Elm is the mean elongation, ?r is the anisotropy in the Langford plane, YSL is the yield strength in the direction of ironing,YSD is the yield strength in the direction of 45 degrees to the direction of rolling, YSc is the yield strength in the direction perpendicular to the direction of rolling, ElL is elongation in the direction of rolling, ELD is elongation in the direction of 45 degrees to the direction of rolling, ELc is elongation in Direction perpendicular to the direction of rolling,r L is the Langford value in the direction of rolling, rD is The langford value in the direction of 45 degrees to the direction of rolling, and rc is the langford value in direction perpendicular to the direction of rolling Slap of steel with the elements defined in Claim 1 up to a heating temperature of 1200 °C or higher, hot-rolling operations so that the finishing of the rolling is finished at that temperature. (deformation temperature A1-50 °C) to (deformation temperature A1-50 °C), coiling operation at 550 °C to 680°C, acid curing operation, rolling operation. Cool at 50% to 85% reduction of rolling, heat treatment to a annealing temperature of 700 °C or above 600 °C or higher at an average heating rate of 1 to 30 °C/s, and then the cooling operation to 600 °C at an average cooling rate of 3 °C/s or more ------------------------- ----------------------------------------- 1.Cold rolled steel plate containing alloy C of 0.030% to 0.060%,Si0.05% or less, Mn0.1% to 0.3%,P0.05% or less,S0.02% or less. , Al0.02% to 0.10%, and N 0.005% or less on a mass basis, the rest is iron and impurities are avoided. No, where its average rake strength (ySm) is 230 Mpa or less. As defined by the following equation (a); its average elongation (Elm) will be 40% or more as defined by the following equation (b); Its ford is 0.7 to 1.4 in the rolling direction and the direction perpendicular to the direction of rolling; the anisotropy in the plane (formula) of its Langford value corresponds to inequality -0.2< or equal to (formula)< or equal to 0.2 as defined by The following equation (c); and the yield elongation of the cold-rolled steel sheet maintained at 170 °C for 60 min is 2% or less in the direction of rolling, the direction of 45 degrees to the direction of ironing, and the direction perpendicular to the direction of ironing: YSm=(YSL+2YSD+YSc/4 (a) Elm=(ElL+2ElD+Elc/4 (b)) (formula)=( rL-2rD+rc (c) where YSm is the mean yield strength, Elm is the mean elongation, (formula)r is an isotropy in the Langford value plane, YSL is the yield strength in the rolling direction, YSD is the yield strength in the 45 degree direction. with the direction of rolling, YSc is the yield strength in the direction perpendicular to the direction of rolling, ElL is elongation in the direction of rolling, ELD is elongation in the direction of 45 degrees to the direction of rolling, ELc is elongation in Direction perpendicular to the direction of rolling, r L is the Langford value in the direction of rolling, rD is the value. langford in the direction of 45 degrees to the direction of rolling, and rc is the langford in the direction perpendicular to the direction of rolling