Microstructural evolution and mechanical response of ERNiCr-3 deposited alloy using gas tungsten wire arc additive manufacturing

Abstract

ERNiCr-3 alloy was deposited using gas tungsten wire arc additive manufacturing (GT-WAAM), and the microstructures and mechanical properties were investigated as a function of sampling direction and height. The (Ti, Nb) C precipitates and segregation could be observed in the interdendritic regions and the degree of segregation was found to become stronger with the distance from the bottom, which should be related to the heat accumulation effect. Such microstructural gradient feature causes the loss of strengthening elements from the dendrite arms and the strength degradation at the top of deposited alloy. The fine-grain remelting zones could be observed between the deposited passes, which resulted from the rapid solidification process. These remelting zones were found to be more resistant to the deformation damage and thus lead to the higher tensile property in the tensile specimens perpendicular to deposited direction as compared with that along the deposited direction. This study can provide useful guidance for the optimization and development of GT-WAAM process for ERNiCr-3 alloy.