Cracking and fracture in welding zone of Fe₃Al and 18-8 stainless steel by TIG

Fe₃Al and 18-8 steel dissimilar materials were welded by tungsten inert gas arc welding(TIG) with filler metal.The cracking and fracture characterization of Fe₃Al/18-8 joint were analyzed by mans of SEM and EPMA.The dislocation morphology was investigated via TEM.The results indicated that the cracks initiated in the fusion zone of Fe₃Al side.The fracture was mainly in trans-granular cleavage mode and there distributed obvious rivers patterns composed of cleavage steps.The weld zone was composed of partial dimples,indicating the better toughness than that of the fusion zone.The dislocations of different density were distributed in the fusion zone of Fe₃Al side,which was the potential cracking of the welding joint.The micro-cracks propagated to Fe₃Al HAZ until rupture when the local stress was larger than critical stress.