Effect of HIP treatment on the microstructure and mechanical properties of a Ni-based superalloy fabricated by selective laser melted method

Abstract

Selective laser melting (SLM) is one of the most emerging additive manufacturing (AM) method through the melting of metal powder to manufacture the full density parts, which will lead to an orientation microstructure and anisotropy mechanical properties. Thus, corresponding post-processing treatments, such as solution treatment (ST) and hot isostatic pressing (HIP), were subjected to the specimens before tests. The effect of the HIP on the microstructure and mechanical properties of SLM Inconel 625 was investigated through uniaxial tension tests at room and elevated temperature. The fracture mechanism was systematically characterized and analyzed using scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). It was found that the microstructure after the HIP process is composed of equiaxed austenite, and the annealing twins are reduced. The tensile test results reveal that the HIP has a significant impact on the plastic behavior of the alloy at high-temperature, and is the main reason for the greatly improved elongation, compared to the ST process.