Abstract:A graded structural material (GSM) with a material transition from TA15 to TC11 was fabricated by wire arc additive manufacturing (WAAM) method. The grain morphology, chemical composition, microstructure and mechanical properties of the as-deposited GSM were all characterized to investigate their variations along the deposition direction. The results indicate that from TA15 to TC11, the grain size decreases and a transition from columnar grains to equiaxed grains occurs. The content of alloy element alters greatly within a short distance, and the width of the mutation zone is 800 μm. Both TA15 and TC11 regions exhibit basketweave microstructure with α-phase and β-phase. However, during the transition from TA15 to TC11, the α-lath becomes fine, which leads to an increase in microhardness. The tensile test shows that the bonding strength at the interface is higher than the longitudinal strength of TA15, and the lateral elongation at the interface is higher than that of TA15 and TC11.

Key words: wire arc additive manufacturing; graded structural material; grain morphology; microstructure; mechanical properties