Microstructure Evolution and Mechanical Properties of As-rolled Ni-20Cr-18W Base Superalloy

Abstract:

Microstructure and mechanical properties of solution strengthened Ni-20Cr-18W rolled superalloy were investigated. Microstructure features and phase composition investigations indicate the average equiaxed grain size of the as-rolled alloy is 20~30 μm (ASTM 7). Significant annealing twins can be observed within the microstructure and most M6C-type carbides mainly disperse on the grain boundary. As-rolled Ni-20Cr-18W superalloy maintains a high tensile strength due to the small grain size. Low ductility of the as-rolled superalloy can be ascribed to M6C-type carbides, which act as crack source on the grain boundary, and the transgranular fracture features with typical dimple-ductile characteristics are observed.