Cold rolled steel sheets having an improved press formability
AssigneeKawasaki Steel Corporation
InventorsSaiji Matsuoka, Takashi Obara, Kozo Tsunoyama, Shunichi Tsugawa, Shigeru Kobayashi, Toshio Ichida
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Abstract
A cold rolled steel sheet or plated steel sheet having an improved press formability as well as excellent phosphatability, resistance to galling and spot weldability is produced by controlling a surface roughness pattern of the steel sheet so as to satisfy a center-line average surface roughness of 0.3-2.0 .mu.m and a regularity parameter in at least one direction of not more than 0.25 defining the regularity of surface roughness.
Claims18
A cold rolled steel sheet having an improved press formability, characterized in that said steel sheet has a surface roughness pattern satisfying a center-line average surface roughness (Ra, .mu.m) of 0.3-2.0 and a regularity parameter (S) in at least one direction of not more than 0.25 showing a regularity of surface roughness represented by the following equations:
- ##EQU6## wherein Xi is a distance between peaks of convex portions at the surface of the steel sheet.
A plated steel sheet having an improved press formability, characterized in that said steel sheet has a surface roughness pattern satisfying a center-line average surface roughness (Ra, .mu.m) of 0.3-2.0 and a regularity parameter (S) in at least one direction of not more than 0.25 showing a regularity of surface roughness represented by the following equations:
- ##EQU7## wherein Xi is a distance between peaks of convex portions at the surface of the steel sheet.
Dependencies are inferred from the claim text.