The influence of B, P and C on heat-affected zone micro-fissuring in inconel type s uperalloy

摘要

The influence of minor elements, viz., C, B and P, present either individually or in combination, on HAZ micro-fissuring susceptibility of Incopel 718 Superalloy was studied. The micro=fissuring susceptibility was evaluated by hot ductility testing in a Gleeble 1500 system and by the measurements of cracks in HAZs around electron beam welds. It was then correlated to the microstructure of the alloys and the segregation of minorelements to the grain boundaries. It was observed that B affected the HAZ micro-fissuring susceptibility very adversely, but the influence of C was only marginal. The addition of P to the B containing alloy made it more susceptible. However, the addition of C to both the B, and B and P containing alloy was beneficiial in reducing the HAZ micro-fissuring susceptibility. The influence of minor elements could be reasponably explained bythe segreation and/or formation of prepipitates on grain boundaries.