Method for manufacturing high strength and high formability hot-rolled transformation induced plasticity steel containing copper

申请公布号：: US6190469(B1)
申请号：: US19980101147
申请日期：: 1998.07.01
申请公布日期：: 2001.02.20
申请人：: POHANG IRON & STEEL CO., LTD.
发明人：: KOH HYANG JIN;KIM NACK JOON;PARK SUNG HO
分类号：: C21D9/46;C21D8/02;C22C38/00;C22C38/02;C22C38/08;C22C38/16;(IPC1-7):C21D11/00;C21D9/52
主分类号：: C21D9/46
摘要：: A method for producing a high strength hot-rolled steel sheet with good formability applicable to automobiles, industrial machines and the like is disclosed. The basic composition of TRIP steel is adjusted wherein Cu is added to improve the strength by precipitation hardening of a fine epsi-Cu. Other conditions are controlled to obtain a tensile strength of over 90 kg/mm2 with good formability. The steel is composed of 0.15-0.3% by weight of C, 1.5-2.5% by weight of Si, 0.6-1.8% by weight of Mn, 0.02-0.10% by weight of Al, 0.6-2.0% by weight of Cu, 0.6-2.0% by weight of Ni, the balance being Fe and inevitable impurities and has a microstructure of multi-phase structure consisting of ferrite, bainite, and retained austenite, or a granular structure (M-A constituents in bainitic ferrite matrix). The steel is finish rolled at a temperature of 750-880° C., water cooled from a water cooling initiation temperature of 680-740° C. to a water cooling termination temperature of 240x(% Mn+% Ni)-140 (° C.) to 540° C., and subsequently coiled at this temperature.