Interface Stability Homogeneity of Large-Scale Laser-Melting-Deposited Titanium Alloy Components

Abstract

Interface stability homogeneity control remains a challenging problem in large-scale laser-melting-deposited titanium (LLMDT) alloy components for aerospace applications. In this study, the homogeneity of the interface stability of LLMDT components after post heat treatment was investigated. Recrystallized grains nucleated and grew in the equiaxed and columnar grain regions in the LLMDT part, whereas they did not form in the interface region because the recrystallization driving force in the interface region was lower than that in the LLMDT part. The microstructures of the LLMDT components showed coarsened α lamellae, and their width varied from 1.65 μm to 2.18 μm. The α lamellae did not completely coarsen during post heat treatment (950 °C/1 h/air cooling+550 °C/4 h/air cooling) because of the low coarsening driving force. For the LLMDT components, the ultimate tensile strength (UTS) and yield strength (YS) were slightly different in different regions owing to the slight difference in the width of the α lamellae. The elongation (EL) of the LLMDT components exhibited no difference, and there was nearly zero anisotropic ductility. The highest fluctuation ratios of the UTS, YS, and EL were 3.11%, 3.8%, and 7.18%, respectively. The tensile properties of the LLMDT components showed no difference in the different regions, indicating interface stability homogeneity.