Optimization of large cast Haynes 282 based on thermal induced cracks: formation and elimination

Abstract

Haynes 282, a wrought material, attracts the attention from casting application due to its excellent mechanical properties. Fracture of large cast Haynes 282 were found before yielding during tensile test in previous researches, but the reasons have not been fully understood. In this study, various heat treatments were designed and applied for large cast Haynes 282 to reveal the fracture before yielding. Thermodynamic calculation, residual stress calculation combined with microstructural examination were utilized to analyze the reasons of fracture. It has been found that there are grain boundary cracking and grain boundary precipitate cracking in the tensile sample. The grain boundary cracking is mostly attributed to the melting of the low melting point phases such as some segregated matrix and μ phases. The grain boundary precipitate cracking is associated with the blocky Ti, Mo rich MC carbides, and it is more likely to be caused by the quenching after the second homogenization treatment. Optimized heat treatment has been proposed and proven to be workable for the large cast Haynes 282.