| 摘要 |
PROBLEM TO BE SOLVED: To provide a press forming method of a steel sheet and a formed article of the steel sheet which can prevent strength deterioration and can improve workability of a high-strength steel sheet having a dual-phase structure by adjusting a forming condition without causing a painting defect.SOLUTION: A steel sheet includes, by mass%, 0.06-0.17% of C, 0.2-1.35% of Si, 1.25-3.1% of Mn, 0.009-0.025% of P, 0.002-0.012% of S, and the balance Fe with inevitable impurities, and has a microstructure which is a dual-phase structure of a ferrite phase and a martensite phase. The steel sheet is heated to a temperature range of an Ac1 transformation point or higher and less than an Ac3 transformation point. After maintaining the temperature range for a set time, which is previously set, press forming is started in the temperature range, press forming is carried out while cooling at a cooling speed for precipitating martensite and is finished in a temperature range lower than a martensite transformation start temperature. |
