Coefficient of Thermal Expansion of AlSi10Mg, 316L Stainless Steel and Ti6Al4V Alloys Made with Laser Powder Bed Fusion

This study investigates the coefficient of thermal expansion (CTE) behavior of LPBF-fabricated AlSi10Mg, 316L stainless steel, and Ti-6Al-4V alloys, focusing on the influence of laser power, scanning speed, and annealing. AlSi10Mg exhibits the highest CTE, but its thermal expansion is highly sensitive to porosity and balling defects. 316L stainless steel shows moderate and stable CTE values, with minimal changes after annealing due to its dense microstructure. Ti-6Al-4V has the lowest CTE, with annealing improving expansion. Higher laser power (100 W) improves fusion, reduces porosity, and stabilizes CTE, while lower power (50 W) increases defects, particularly in AlSi10Mg and Ti-6Al-4V. Scanning speed significantly influences porosity, with 0.4 m/s providing an optimal balance between melt efficiency and defect minimization. Annealing enhances CTE uniformity by reducing the lack of fusion defects and refining grain structures, with the greatest improvements seen in low-laser-energy conditions. These findings provide valuable insights for optimizing LPBF parameters to enhance thermal stability and reliability in aerospace, biomedical, and structural applications.