In Situ Elimination of Pores During Laser Powder Bed Fusion of Ti–6.5Al–3.5Mo–l.5Zr–0.3Si Titanium Alloy

The printing quality of components manufactured using laser powder bed fusion(LPBF)generally depends on the presence of various defects such as massive porosity.Thus,the efficient elimination of pores is an important factor in the production of a sound LPBF product.In this study,the efficacy of two in situ laser remelting approaches to eliminating pores during the LPBF of a titanium alloy Ti–6.5 Al–3.5 Mo–l.5 Zr–0.3 Si(TC11)was assessed both experimentally and computationally.These two remelting methods are surface remelting and layer-by-layer printing and remelting.A multi-track multi-layer phenomenological model was established to analyze the variation of pores with the temperature and velocity fields.The results showed that surface remelting with a high laser power,such as 180 W,can eff ectively eliminate pores within three deposited layers.However,such remelting could not reach defects in deeper regions.Layer-by-layer remelting with a 180 W laser could eff ectively eliminate the pores formed in the previous layer in real time.The results obtained in this study can provide useful guidance for the in situ control of printing defects supported by real-time monitoring,feedback,and operating systems of an intelligent LPBF equipment.