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<p>This study investigates a dual-phase laser scanning (DPLS) strategy in laser powder bed fusion (LPBF) to enhance the mechanical performance of 17 − 4 precipitation-hardening (17-4PH) stainless steel for future nuclear energy component design. DPLS is defined as a two-step laser exposure applied to each layer, comprising a primary melt scan and an in-situ remelting pass that adjusts thermal gradients, promotes improved fusion, and facilitates microstructural refinement. In this study, DPLS was executed using two distinct scan-path variants—(i) a repeated-path design and (ii) a non-repeated, perpendicular-path design with modified remelting speed—to more precisely control the layerwise thermal history. Porosity and pore morphology were quantified by X-ray computed tomography (XCT), microstructure (grain size/texture) by electron backscatter diffraction (EBSD), and tensile behavior by uniaxial testing. All DPLS builds maintained relative density (RD) above 99% and showed notable gains in strength and ductility. The repeated-path DPLS achieved a yield strength of 955.2 ± 26.8&#xa0;MPa, an ultimate tensile strength (UTS) of 1222.8 ± 30.5&#xa0;MPa, and 12.02% elongation. The non-repeated, perpendicular-path DPLS reached 722.9 ± 21.9&#xa0;MPa YS and 1193.4 ± 18.2&#xa0;MPa UTS, with improved ductility attributed to favorable crystallographic orientations. To strengthen the study, comparisons with literature using combined heat-treatment routes indicate that repeated-path DPLS can reach similar property levels within a single build. These results show that DPLS refines martensitic microstructure and defect morphology while preserving high RD, offering a process-integrated, cost- and time-efficient pathway to optimize 17-4PH components fabricated by LPBF.</p>

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Dual-phase laser scanning for enhanced mechanical properties in laser powder bed fusion deposited 17-4PH stainless steel: implications for nuclear energy component design

  • 期刊论文

  • 发表日期：

    2026年1月4日

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  • Dan T. Nguyen,
  • Reza Mirshams,
  • Madhavan Radhakrishnan,
  • Narendra Dahotre

摘要

This study investigates a dual-phase laser scanning (DPLS) strategy in laser powder bed fusion (LPBF) to enhance the mechanical performance of 17 − 4 precipitation-hardening (17-4PH) stainless steel for future nuclear energy component design. DPLS is defined as a two-step laser exposure applied to each layer, comprising a primary melt scan and an in-situ remelting pass that adjusts thermal gradients, promotes improved fusion, and facilitates microstructural refinement. In this study, DPLS was executed using two distinct scan-path variants—(i) a repeated-path design and (ii) a non-repeated, perpendicular-path design with modified remelting speed—to more precisely control the layerwise thermal history. Porosity and pore morphology were quantified by X-ray computed tomography (XCT), microstructure (grain size/texture) by electron backscatter diffraction (EBSD), and tensile behavior by uniaxial testing. All DPLS builds maintained relative density (RD) above 99% and showed notable gains in strength and ductility. The repeated-path DPLS achieved a yield strength of 955.2 ± 26.8 MPa, an ultimate tensile strength (UTS) of 1222.8 ± 30.5 MPa, and 12.02% elongation. The non-repeated, perpendicular-path DPLS reached 722.9 ± 21.9 MPa YS and 1193.4 ± 18.2 MPa UTS, with improved ductility attributed to favorable crystallographic orientations. To strengthen the study, comparisons with literature using combined heat-treatment routes indicate that repeated-path DPLS can reach similar property levels within a single build. These results show that DPLS refines martensitic microstructure and defect morphology while preserving high RD, offering a process-integrated, cost- and time-efficient pathway to optimize 17-4PH components fabricated by LPBF.