| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel sheet member having high strength and high toughness, and a production method therefor. SOLUTION: The steel sheet member is composed of 0.15-0.4 wt.% C content and 1.0-5.0 wt.% Mn content or the total content of Cr, Mo, Cu, Ni and Mn, 0.02-2.0 wt.% at least one content of Si and Al and the balance Fe with inevitable impurities, and made to be ≤5 μm average grain diameter of martensitic phase and ≥1,200 MPa tensile strength. Further, in the steel sheet member, at least one selected from B, Ti, Nb and Zr, is contained with ≤0.1 wt.% content. In the steel sheet member, the steel material is heated to 675-950°C, the maximum heating temperature T°C at ≥10°C/sec temperature raising speed, and after holding the maximum heating temperature T°C for ≤(40-T/25) s, the martensitic phase is generated by cooling to ≤Ms point as the generating temperature of the martensite from the maximum heating temperature T°C at ≥1.0°C/s cooling speed. COPYRIGHT: (C)2010,JPO&INPIT
|
