Coupling effects of high magnetic field and annealing on the microstructure evolution and mechanical properties of additive manufactured Ti–6Al–4V

Additive manufacturing (AM) is playing a critical role in the areas of in-space intelligent manufacturing and on-orbital serving technologies. One of challenges is to reveal the composition-processing-microstructure-property relationship during post-treatment process, which would promote the AMed-product with excellent quality. In present work, the integration of heat and magnetic fields provides an approach to optimize microstructures and to enhance the mechanical properties of the selective laser melting (SLM) fabricated Ti–6Al–4V alloy. The conditions for post-treatment processes are set up to 400 °C for 30 min with 2 T, 4 T, 6 T, 8 T and 10 T, respectively. This coupling effects not only promote the phase transformation of α'→α+β, but also modify the width of the α'/α phases. The α'/α morphology after post-treatment becomes finer than the as-built ones, attributing to grain refinement strengthening. Moreover, the yield strength and the ductility of the annealed specimen in 8 T high magnetic field are 1092.1 MPa and 15.1% respectively, which could beat the classical reported SLM-fabricated ones and be comparable to the wrought ones. This work provides the connections between magnetic heating treatments and mechanical properties, paving a path to accelerate the development of space technology and exploration.