Effects of HIP Conditions on the Microstructure and Creep Properties of Ni-base Superalloy Fabricated by Laser Powder Bed Fusion

Abstract

Ni-base superalloy (IN718) manufactured by laser powder bed fusion (L-PBF) was subjected to hot isostatic pressing (HIP) under various conditions. The effects on microstructure and defects in the builds were investigated, and tensile strength at room and high temperatures and tensile creep properties were evaluated. After HIP at lower temperature, Laves phase in as-built specimen was dissolved and the δ phase was precipitated. However, the δ phase dissolved in the matrix as the HIP temperature increased. When the HIP temperature was less than 1323 K, the tensile strength was almost as high as the forged specimen. The creep rupture strain increased with increasing HIP temperature and was the highest at 1393 K. However, the strain was lower than that of the forged specimen. It was found that there was a factor that reduce the creep rupture strain specific to the HIP specimens.