| 摘要 |
PROBLEM TO BE SOLVED: To provide an automobile frame material made of a high strength electric resistance welded tube to which tapping screws can be screwed with small torque and which has excellent stability in quality. SOLUTION: A steel having a composition comprising 0.01 to 0.20% C,≤1.5% Si,≤2.5% Mn,≤0.05% P,≤0.02% S, 0.005 to 0.10% acid soluble Al, 0.01 to 0.15% Ti and/or 0.01 to 0.15% Nb, and, if required, comprising one or more kinds selected from 0.01 to 0.30% Zr, 0.01 to 0.30% V, 0.01 to 0.30% Mo, 0.01 to 0.30% Cr and 0.05 to 1.00% Ni, and in which C equivalent defined by formula (1): C equivalent=C+1/6Mn+1/24Si+1/5Cr+1/4Mo+1/14V+1/40Ni is controlled to 0.25 to 0.6% is continuously cast. Through hot rolling at a finishing temperature of an Ar<SB>3</SB>transformation point or higher and a coiling temperature of 600 to 450°C, pickling and cold rolling at a cold rolling ratio of 10 to 75%, a cold rolled steel strip having increased strength is produced. With the cold rolled steel strip as the stock, both the edge parts in the width direction are welded, thus the automobile frame material made of a high strength electric resistance welded tube having excellent tapping properties is obtained. COPYRIGHT: (C)2006,JPO&NCIPI |
