| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-strength quenched compact excellent in corrosion resistance, workability and fatigue resistance so that the corrosion resistance and the workability of the quenched compact are equivalent to or above than those of a cold molding in a galvanized steel sheet, and to provide a method for manufacturing the high-strength quenched compact. SOLUTION: A galvanized steel sheet having a galvanized layer containing Al and Si of≥0.15 mass% and <2 mass% independently or in combination is partly heated at the temperature equal to or higher than Ac3 point and≤950°C, and partly heated at the temperature≥500°C and below Ac3 point at the same time, and started to be cooled. After cooling the steel sheet≤730°C and≥500°C without 60seconds, and then, pressed and quenched within the above temperature range to obtain the joint product having a high-strength portion of≥1,000 MPa and a low-strength portion of≤800 MPa in terms of the tensile strength after the hot stamping while a phase of≥30 g/m<SP>2</SP>consisting of≥5 mass% and≤30 mass% Fe is contained on a surface of the steel sheet of the joint product after the quenching. COPYRIGHT: (C)2010,JPO&INPIT |
