Patent ID: 6682829
Filing Date: 2004-01-27
Classification: C21D,C22C,Y10T

Abstract:
A welded steel pipe having excellent hydroformability having a composition comprising, on the basis of mass percent:about 0.05% to about 0.3% C; about 0.01% to about 2.0% Si; more than about 1.5% to about 5.0% Mn: about 0.01% to about 0.1% P; about 0.01% or less of S; about 0.01% to about 0.1% Cr; about 0.01% to about 0.1% Al; about 0.01% to about 0.1% Nb: about 0.01% to about 0.3% Ti: about 0.001% to about 0.01% N; and the balance being Fe and incidental impurities, wherein the welded steel pipe has a tensile strength of 780 MPa or more, and the nÃ—r product of the n-value and the r-value is about 0.15 or more.