The effect of electron beam surface remelting on the wear behavior of Ti-6Al-4V by EBF3

Ti-6Al-4V alloy is one of the key materials in the aerospace and chemical industries. Additive manufacturing (AM), e.g., electron beam freeform fabrication (EBF3), is increasingly applied to manufacture the titanium part due to its low cost, high flexibility, high efficiency, etc. At the same time, the wear resistance and hardness of the Ti-6Al-4V alloy synthesized by AM can deteriorate during fabrication. In this paper, electron beam surface remelting (EBSR) is used to improve the wear resistance and hardness of the titanium alloy made by EBF3. The phase, microstructure, element composition, and wear track profile of layers remelted at three EBSR-beam currents were analyzed. According to the results, the synthesized alloy consists of a homogeneous α′ martensitic structure with numerous embedded nano-scale particles rather than a dual α + β lamellar structure when a rapid cooling rate is applied during EBSR. Simultaneously, the coarser prior-β grain boundary was eliminated in the process. The wear rate of the as-obtained remelted layers at the EBSR-beam currents of 0 (as-deposited), 3, 6, and 9 mA was determined as 7.7 × 10−10, 5.7 × 10−10, 7.9 × 10−10, and 8.9 × 10−10 m3/Nm, respectively. The evolution of the structure accounts for the high hardness and superior wear resistance. EBSR successfully modified the as-deposited microstructure to achieve favorable wear properties, which widens the application potential and extends service life.