Development of High-Speed Double‑sided Friction Stir Welding Technology with Pre-heating Process for Automotive Advanced High Strength Steel
摘要
Double-sidedDouble-sided friction stir weldingFriction stir welding (FSW) with pre-heatingPre-heating process utilizing high frequency induction heating was studied in an attempt to enhance the travel speed for welding of automotive advanced high strength steelAdvanced high strength steel. The experiments were performed on butt joints of 1.6 mm thick 1180N/mm2 grade steel sheets. The maximum welding speed free from weld defect or incompletion was 6.0 m/min, exhibiting a 50% increase compared with the case without pre-heatingPre-heating and fairly comparable with laser beam welding, one of the primary automotive welding processes. According to the metallographic observation of welds, the plastic flow was diminished when a thermal gradientThermal gradient developed within the stir zone, which tended to be obvious with high travel speed. The pre-heatingPre-heating process was studied to make a positive impact on homogenizing the temperature field and promoting the plastic flow within the stir zone, which led to increasing the maximum travel speed.