3D grain structure modelling of intergranular fracture in forged Haynes 282

Abstract

In this paper, 3D grain structure finite element models are used to simulate the anisotropic tensile ductility of Ni-based superalloy Haynes 282. The anisotropic ductility is believed to be caused by a nonuniform distribution of both grain size and large carbides, which influences the intergranular fracture of the material. To simulate this anisotropic ductility, grain structure models with nonuniform grain size distribution are generated by Voronoi tessellation. Additionally, the mechanical behaviour of the models is governed by crystal plasticity and the intergranular fracture is simulated by cohesive elements embedded in the grain boundaries. The paper investigates how the shape and orientation of regions with smaller grains in the grain structure model influence the cracking behaviour. Furthermore, the study also focuses on modelling the embrittling impact of large carbides in the grain boundaries. Results from the simulations qualitatively correspond to experimental results, which supports the assumption that the nonuniform grain size distribution and the large carbides cause the anisotropic tensile ductility seen in forged Haynes 282.