Effect of microtextures on the intermediate temperature fracture behavior of additive-manufactured Ni-based overlay

Texture components with specific orientations are found to play important roles in crack and fracture phenomena. In this study, nickel-based alloy overlays with different texture intensities were directly produced by wire and arc additive manufacturing (WAAM) processes. Results of hardness and tensile tests from room to elevated temperatures showed global differences in strength, ductility and cracking susceptibility between the deposit with the Cube texture and the deposit with the Brass texture. The formation mechanism of different textures during WAAM processes was elucidated. Then the deformation of individual texture grains and incompatible deformation among them were analyzed, and their effects on the fracture mechanism at the intermediate temperature were also investigated. During the deformation, the Brass grains, with relatively lower Schmid factors compared to the Cube grains, were hard to activate (111 )<1-10> system slip without rotation, which led to significant strain accumulation at the grain interior and boundaries. The incompatible deformation and discontinuous slip transfer between differently orientated grains, especially the Brass grains, induced cracking and exacerbated the ductility within the intermediate temperature range. (C) 2019 Elsevier B.V. All rights reserved.