EFFECT OF PRE-FATIGUE ON DYNAMIC AND STATIC TENSILE PROPERTIES OF LASER WELDED BUTT JOINTS BETWEEN DIFFERENT HIGH STRENGTH STEEL PLATES

摘要

In this research, the effects of pre-fatigue on the dynamic and quasi-static tensile properties of laser welded butt joints between three kinds of steel plates, i.e. HR270, HR590 and HR780 steels, were investigated using tensile split Hopkinson bar apparatus. There were no significant effects of prefatigue on the dynamic and static tensile properties of HR780-HR270 and HR780-HR590 joints.Their fracture occurred in the middle of the weaker base metal parts. However, one or two in three pre-fatigued HR780-HR780 joint specimens broke at the heat affected zone, irrespective of strain rate. Their elongation decreased dramatically from that of the virgin specimens, although there are no changes in the tensile strength.