Modelling and optimisation of the post-weld heat treatment of γ′ precipitation and hardness on Inconel X-750 using the response surface methodology

This work describes a post-weld heat treatment (PWHT) for Inconel X-750. The following PWHT variables were examined: the solution temperature, PWHT temperature, and PWHT time. In this research, the application of the response surface methodology and Box-Behnken design in a mathematical model was investigated and optimised. The resulting materials were examined using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM) in the fusion zone (FZ). The experimental results reveal that using a full quadratic model with the proposed mathematical model of the γ′ precipitation size and γ′ hardness in the FZ, the obtained correlation of the hardness and γ′ precipitate size showed a reasonable linear relationship.