The Joints Characteristics of Friction Welded Titanium and 321 Stainless Steel

摘要

The microstructural change and mechanical properties of friction welded Ti /321 stainless steel joint have been investigated with various friction welding conditions for example friction time and upset pressure. Very fine and equaxed grain structure was observed near interface and its size was about 10 times smaller than those of the base metals. The shape of the interface showed the non-straight line at the 475MPa of upset pressure. This non-straight line improved the Ti/321 stainless joint property due to the increased joint area. The hardness profile near the weld zone showed higher value those of the Ti and 321 stainless steel base metal. This result may be occurred by the intermetallic compound of Ti/ 321 stainless steel and the stress induced martensite transformation of 321 stainless side at the higher upset pressure. The tensile strength increased as increasing upset pressure and reached 420MPa at 475MPa of upset pressure. The fracture occurred at Ti side at higher upset pressure and it meant the joint strength was higher than that of the Ti.