Welding solidification cracking susceptibility and behavior of a Ni-28W-6Cr alloy

Welding solidification cracking of alloys is associated with the range of solidification temperature that can be greatly affected by the amount of refractory metals and other additives. In this work, solidification cracking of Ni-28W-6Cr alloy with high W content was studied by gas tungsten arc welding, showing that the welding current, alloying elements and precipitates all affect the cracking susceptibility. The lengths of cracks increase linearly with the welding current in the range from 150 to 250 A. The relatively high cracking susceptibility is mainly attributed to the high content of Si, which tends to segregate with other elements including W, Cr, Mn as films or components with low melting point in the last solidification stage and weaken the binding force of grain boundaries. Moreover, the existence of precipitated continuous eutectic M6C carbides in the grain boundaries also acts as nucleation sites of crack initiation, and the cracks often propagate along solidification grain boundary.