Characteristics of cracks in heat affected zone of ductile cast iron in powder welding process

Cracking can occur in the HAZ of ductile cast iron hardfaced with nickel base self-fluxing alloy using oxyacetylene powder welding. Since there is no partially melted zone and almost no dissolution of graphite nodules, the cracking has metallurgical characteristics, which differentiate it from the cracks reported in the case of arc welding processes. The cracks initiate within the graphite nodules and propagate through the martensitic matrix. It is shown that the cracking process is predominantly controlled by the residual stresses.