Abstract
Laser powder bed fusion (LPBF) is a promising additive manufacturing technology, but porosity defects impair its widespread application. A universal relative density equation is essential for elucidating the physical mechanisms of density and optimizing process parameters. Here, a global, stepwise, centrally dense hexagonal design of experiments is applied to the additive manufacture of 65 GH4169 nickel superalloy samples under varying parameter conditions. Inspired by the Morse potential energy function, a universal relative density equation is first established using a data-physics fusion driven (DPFD) approach by introducing contact angle (θ) and boiling factor (b). This equation uncovers the dynamic evolution and competing mechanisms of relative density under different laser volume energy density (E). The results illustrate that the relative density increases rapidly as E increases in the low E regime, but it falls slowly as E exceeds the optimal range (process window); meanwhile, the density rapidly increases as θ decreases in the low E regime, but it falls slowly as b increases when E exceeds the optimal process window. This progress breaks through the limitations of P-v space design. This study provides theoretical guidance and a simple basic technical choice for exploring the fabrication of fully dense products using LPBF.