Compressive performance and defects healing behavior of pure tungsten fabricated by LPBF coupled with subsequent hot isostatic pressing

Abstract

Additively manufactured pure tungsten parts are prone to defects such as gas pores, lack of fusions, and cracks, which significantly confines its wider application. Here, the hot isostatic pressing (HIP) treatment was employed to improve the microdefects using high temperature and high pressure conditions. The microstructure evolution and compressive performance were systematically investigated. The results revealed that the HIP treatment contributed to filling the gas pores and lack of fusions, and healing the crack to discontinuous chain-like pores. The grain size ascended with the more concentrated distribution at both views, and the texture orientation evolved towards the 〈101〉 and 〈111〉, accompanied by the weaker 〈001〉. In addition, the LAGBs penetrated the HGABs storing the strain energy required for crack propagation. The compressive performance of additively manufactured pure tungsten was significantly enhanced, with the compressive strength increasing from 944 MPa to 1263 MPa (about 33.8 %) and the compressive strain rising from 11.0 % to 16.0 % (around 45.4 %). These results aid in offering another way to understand the micro defects and heal them of pure tungsten or other refractory metals.