Patent ID: 6210496
Filing Date: 2001-04-03
Classification: C22C

Abstract:
A cold rolled steel sheet having high strength, high formability and excellent crushing performance, comprising:ferrite as a major phase; anda minor phase consisting of martensite, acicular ferrite and retained austensite,wherein the ratio of the minor phase in the steel structure is 3-40%;wherein the ratios of martensite, retained austenite and acicular ferrite in the minor phase are 10-80%, 8-30% and 5-60% respectively; andwherein the steel sheet comprises:0.05-0.40 mass % of C,1.0-3.0 mass % of Si,0.6-3.0 mass % of Mn,0.02-1.5 mass % of Cr,0.010-0.20 mass % of P,0.01-0.3 mass % of Al, andthe remainder consisting essentially of Fe.