| 摘要 |
When friction-stir welding steel sheets, for the rotating tool, rotation speed RS is set 100-1000 rpm, rotational torque RT 50-500 Nm, and travel speed TS 10-1000 mm/min, and HIPT (kJ/mm 2 ) is controlled to be in a range of 0.3-1.5. The steel sheets that are used have a composition including 0.01-0.2 mass% of C, 0.5-2.0 mass% of Mn, 0.6 mass% or less of Si, 0.030 mass% or less of P, 0.015 mass% or less of S, and 0.0060 mass% or less of O, with a content of Ti [%Ti] and a content of N [%N] being restricted in relation to the HIPT, Ceq being 0.5 mass% or less, and the balance being Fe and incidental impurities. As a result, local change in the frictional heat and plastic flow generated by friction can be prevented, yielding a weld portion with uniform and good toughness. |
