Microstructure and high cycle fatigue property of HIPed GH4169 superalloy fabricated by laser solid forming

The fatigue property of laser solid forming (LSF) GH4169 superalloy is worse for the influences of the coarse and uneven distributed grains and the existence of large amount of twin boundaries. The post hot isostatic pressing (HIP) process is used to the LSF GH4169 superalloy sample to improve its high cycle fatigue property owing to the enhancement of density and the uniform of the grain structure, combined with the post heat treatment. The results show that the grains are refined to an average size of 100~200 μm from 50~500 μm and their spherical degrees are raised. The interface structure also changes and the volume fraction of <111>60℃ twin boundary clearly decreases. HIP can effectively improve the high cycle fatigue property of LSF GH4169 superalloy, however, it is still lower than the standard value of forged GH4169.