| 摘要 |
In a friction stir welding method, steel sheets or plates used are each made of high-strength welding structural steel having a chemical composition controlled to a predetermined range, a Pcm value calculated by formula (1) satisfying 0.18 ‰¤ Pcm ‰¤ 0.30, and the balance being Fe and incidental impurities, friction stir welding conditions fall under ranges of tool rotational speed: 100 rpm to 1000 rpm, tool rotational torque: 50 N·m to 500 N·m, and welding speed: 10 mm/min to 1000 mm/min, and HI defined by formula (2) is within a range of 1.5 to 20, and satisfies formula (3) in relation with Pcm, Pcm % = C + Si / 30 + Mn + Cr + Cu / 20 + Ni / 60 + Mo / 15 + V / 10 + 5 B HI kJ / mm = 6.28 × RT × RS / TS / 1000 1.5 × 10 9 × Pcm 13.8 ‰¤ HI ‰¤ 2.1 × 10 8 × Pcm 10.6 |
