Additive manufacturing processes such as laser powder bed fusion (LPBF) introduce residual stresses that can cause part distortion and reduced mechanical properties. LPBF process parameters are often selected to give high relative density and specific mechanical properties; however, it is not straightforward to predict their combined influences on residual stresses. This study examines the relationships between various LPBF parameters (laser power, laser scanning speed, and build plate preheating) and residual stresses in LPBF fabricated AlSi10Mg and Ti6Al4V materials using the bridge curvature method where the sample total flatness deviation (FLTt) is utilized as a measure of the relative residual stress magnitude. For AlSi10Mg, the residual stresses were significantly influenced by any changes in the LPBF process parameters, and a strong positive correlation was found between the solidification cooling rates and the FLTt values across all LPBF process parameter groups. Such results highlight the importance of understanding how LPBF process parameters affect the solidification process for residual stress management in AlSi10Mg. In contrast, while FLTt values were generally higher for Ti6Al4V compared to AlSi10Mg, only build plate preheating showed a significant effect on the residual stresses which was attributed to its effect on the cooling rates during the martensitic phase transformation. Such results highlight that while LPBF process parameters may influence residual stress formation via the sample cooling rates, care must be taken to understand the temperature range over which the cooling rates most strongly influence the residual stresses for a specific alloy system.
Taufiq et al. (Fri,) studied this question.