| 摘要 |
A friction stir welding method, wherein: there is used, as a steel sheet, steel for a high-strength welded structure in which the component composition is adjusted to a predetermined range and the Pcm value calculated by the following expression (1) satisfies 0.18 ≤ Pcm ≤ 0.30, the balance being Fe and unavoidable impurities; and the welding conditions for friction stirring are such that the tool rotation speed is 100-1000 rpm, the tool rotation torque is 50-500 N·m, the welding speed is 10-1000 mm/min, and HI defined by the following expression (2) is within a range of 1.5-20 and has a relationship with Pcm satisfying the range in the following expression (3). Pcm(%) = C + Si/30 + (Mn + Cr + Cu)/20 + Ni/60 + Mo/15 + V/10 + 5B... (1) HI(kJ/mm) = (6.28 × RT × RS)/TS/1000... (2) 1.5 × 109 × (Pcm)13.8 ≤ HI ≤ 2.1 × 108 × (Pcm)10.6... (3) |
