Microstructure transition gradients in titanium dissimilar alloy (Ti-5Al-5V-5Mo-3Cr/Ti-6Al-4V) tailored wire-arc additively manufactured components

The nature of the chemical mixing and microstructure gradients that occur across interface transition, when manufacturing tailored components with two high-performance dissimilar titanium alloys (Ti-6Al-4V (Ti-64) Ti-5Al-5V-5Mo-3Cr (Ti-5553)) by wire-arc additive (WAAM) process, are reported. It has been shown a relatively long-range gradient occurs during transition between layers produced different alloys, due to convective in melt pool substrate new alloy wire. This resulted stepwise exponential decay composition profile normal layers, width which can be described simple dilution law, steep local seen within boundary at fusion each individual layer. alloy-alloy had little effect on β-grain structure. However, they strongly influenced transformation microstructure, their parent β-phase stability β → α kinetics reaction sequence. transitioning from Ti-64 Ti-5553 was significantly more abrupt, compared depositing reverse order. Under WAAM thermal conditions, appears sensitive adding β-stabilising elements than is diluted Ti-64, because high cooling rates, stabilisation phase readily suppresses nucleation through transus, lamellar abruptly replaced finer scale laths generated precipitation subsequent reheating cycles.