Dual-Phase Laser Scanning for Enhanced Mechanical Properties in Laser Powder Bed Fusion Deposited 17-4PH Stainless Steel

This study investigates the application of the dual-phase laser scanning (DPLS) technique in laser powder bed fusion (LPBF) to enhance mechanical properties of 17 − 4 precipitation hardened (PH) stainless steel. While LPBF is widely used for its precision and ability to produce complex geometries, challenges such as porosity and inconsistent material properties remain significant hurdles. The DPLS technique, incorporating an initial melt followed by a remelt, aims to address these challenges by improving interlayer bonding and relative density (RD). Experimental evaluations, including Archimedes’ method and X-ray tomography, revealed that despite a marginal decrease in relative density compared to single-phase scanning, the DPLS process yielded notable improvements in mechanical properties. Samples fabricated using repeated-pattern DPLS, exhibited an ultimate tensile strength (UTS) of 1222.8 ± 30.5 MPa and a yield strength (YS) of 955.2 ± 26.8 MPa, demonstrating significant enhancements in strength and ductility. Similarly, samples fabricated using non-repeated-pattern DPLS achieved the UTS of 1193.4 ± 18.2 MPa and the YS of 722.9 ± 21.9 MPa, with improved elongation attributed to favorable crystallographic orientations. Additionally, comparisons with hot isostatic pressing (HIP)-treated samples, which exhibited the UTS of 910.3 ± 7.9 MPa and the YS of 598.8 ± 36.9 MPa, suggest that DPLS can potentially reduce reliance on costly post-processing treatments. These findings highlight the potential of DPLS to optimize mechanical performance in LPBF-fabricated 17-4PH stainless steel components, offering a pathway toward more efficient and cost-effective additive manufacturing solutions.