The effect of hot isostatic pressing on crack healing, microstructure, mechanical properties of Rene88DT superalloy prepared by laser solid forming

Crack characterization in Rene88DT superalloy prepared by laser solid forming (LSF)was investigated; the effect of hot isostatic pressing (HIP) on crack healing, microstructure and mechanical properties was also analyzed. It was found that cracks in LSFed Rene88DT mainly nucleate and propagate in the overlap zone of laser-deposited passes, and can be attributed to the liquation cracks. The size and amount of the cracks in LSFed Rene88DT are significantly affected by the overlap of as-deposited passes. Through HIP processing, crack healing occurred, which leads to a substantial improvement of the mechanical properties of LSFed Rene88DT superalloy. However, the insufficient overlap will result in very large cracks in the deposit, which makes the diffusion bonding during HIP not completely eliminate the local segregation of Ti and Nb in the crack healing region. (C) 2008 Elsevier B.V. All rights reserved.