A multi-scale study of Inconel 625 powders HIP process and construction of HIP maps

A multi-scale analysis of Inconel 625 powders hot isostatic pressing (HIP) has been carried out numerically by finite element method base on the modified Shima model. Numerical results have indicated the capsule deformation and powders movement at different HIP parameters. Furthermore, five interrupted experiments have given a vivid description about the powder densification process in the micro level. Results have shown that at the initial stage of HIP, densification process is caused by the movement, arrangement, and aggregation of powders. When the coordinate number reaches to the maximum, plastic deformation plays the leading role in densification. When the applied pressure is bigger than the yield stress of powders, parts of the particles will be squeezed into the voids and all the powders particles are linked into a whole unit. At the last stage, plastic flows are relatively small; diffusion and power law creep mechanisms play the leading role in densification. Powder atoms are squeezed into the residual porosity slowly with the help of isostatic temperature and pressure. Based on the above micro analysis, coupled with the original empirical densification model, the HIP maps of Inconel 625 powders have been constructed. And the HIP maps have depicted how the relative density changes with HIP temperature, pressure, and duration time. Effects of particle size on the densification have also been considered in the HIP maps.