Solidification characteristics and high temperature tensile properties of Ni-based superalloy IN713C

Abstract

The solidification characteristics and high temperature tensile properties of IN713C superalloy were investigated using directional solidification methods at withdrawal rates of 10, 50 and 100 µm/s, respectively. The results show that carbide morphologies change from block and long strip to short rod and granular with increasing withdrawal rate. The increase of withdrawal rate promotes the microsegregation of Mo, Nb and Zr, and contributes to precipitation of the γ/γ’ eutectic and boride. With the withdrawal rate increasing from 10 µm/s to 50 µm/s, the high temperature yield strength, ultimate strength and elongation of the IN713C alloy increased by 11.8%, 18.3% and 64% respectively. The increase of the γ/γ’ eutectic and boride lead to slight decrease in strength when the withdrawal rate increased from 50 µm/s to 100 µm/s. The fractographic observation of tensile specimen indicates that the integrate carbide particles are an overwhelming majority at a higher withdrawal rate. When the withdrawal rate decreases, the particles become larger and more secondary cracks are generated. The morphology of carbides affects the tensile fracture mechanism of the alloy. With the decrease of carbide size, the crack source of the IN713C alloy changed from brittle carbides to the interface between carbide and matrix.