A study of crack and fracture on the welding joint of Fe3Al and Cr18–Ni8 stainless steel

Fe3Al and Cr18–Ni8 steel dissimilar materials were welded by tungsten inert gas arc welding (TIG) with filler metal in this paper. The micro-crack and the fracture in the welding zone were analyzed by means of scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA), the morphology of the dislocation was analyzed by means of the transmission electron microscopy (TEM). The results indicated that the cracks of the Fe3Al/Cr18–Ni8 welding zone were produced in the fusion zone of Fe3Al side, the trans-granular cleavage crack was the main form of the fracture, and the river pattern distributed in the cleavage face which was composed of the cleavage steps. The dislocations with the different density distributed in the fusion zone, which was the potential crack origin of the Fe3Al/Cr18–Ni8 joint. The micro-crack propagated to the heat-affected zone of Fe3Al side until rupture when the local stress was larger than critical stress.

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