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<p>Considering the long period service life, stainless steel 316L is widely utilized in multiple fields, such as aerospace, military, automobile, etc. However, the 316L’s additively manufacturing (AM) mechanical property is not guaranteed due to limitation of process itself. A newly combined laser powder bed fusion (LPBF) with ultrasonic re-melting (URM) is proposed to get rid of the fabricated defects. To be specific, the re-melting is conducted in each laser fabricated powder layer, meanwhile the ultrasonic vibration (USV) is added in the laser re-melting stage to reduce the porosity. The effects of USV on the surface contour quality, porosity, microstructure, texture, and mechanical properties of the samples were analyzed. Compared with conventional LPBF (C-LPBF) and re-melting LPBF (RM-LPBF) processes, the results show that USV significantly reduces porosity, eliminates large pores, refines grains and inhibits texture-preferred orientation. Among them, the porosity under the URM-LPBF condition is 0.034%, which is approximately 70% lower than that under the C-LPBF condition (0.114%), and approximately 84% lower than that under the RM-LPBF condition (0.212%). The equivalent radius of defects under the URM-LPBF condition is less than 15&#xa0;μm, which is approximately 55% lower than that under the other two conditions (33&#xa0;μm). Both microhardness and fatigue life were improved. When the applied stress amplitude is 193&#xa0;MPa, the fatigue life under the URM-LPBF condition is about 19% higher than that under the RM-LPBF condition and about 36% higher than that under the C-LPBF condition. The improvements in the comprehensive properties of the samples prove the feasibility of using USV to enhance LPBF forming. This study provides an innovative solution to the issue of powder polarization under ultrasonic action, thereby eliminating the anisotropy and enhancing the quality of LPBF, which can be a hopeful high performance strategy in metal powder AM fields.</p>

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Microstructure and mechanical properties of 316L additively manufactured via ultrasonic re-melting laser powder bed fusion

  • 期刊论文

  • 发表日期：

    2025年10月23日

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  • Yue Lu,
  • Cong Sun,
  • Dawei Wang,
  • Yang Liu,
  • Zhenxing Jiang,
  • Shu Huang

摘要

Considering the long period service life, stainless steel 316L is widely utilized in multiple fields, such as aerospace, military, automobile, etc. However, the 316L’s additively manufacturing (AM) mechanical property is not guaranteed due to limitation of process itself. A newly combined laser powder bed fusion (LPBF) with ultrasonic re-melting (URM) is proposed to get rid of the fabricated defects. To be specific, the re-melting is conducted in each laser fabricated powder layer, meanwhile the ultrasonic vibration (USV) is added in the laser re-melting stage to reduce the porosity. The effects of USV on the surface contour quality, porosity, microstructure, texture, and mechanical properties of the samples were analyzed. Compared with conventional LPBF (C-LPBF) and re-melting LPBF (RM-LPBF) processes, the results show that USV significantly reduces porosity, eliminates large pores, refines grains and inhibits texture-preferred orientation. Among them, the porosity under the URM-LPBF condition is 0.034%, which is approximately 70% lower than that under the C-LPBF condition (0.114%), and approximately 84% lower than that under the RM-LPBF condition (0.212%). The equivalent radius of defects under the URM-LPBF condition is less than 15 μm, which is approximately 55% lower than that under the other two conditions (33 μm). Both microhardness and fatigue life were improved. When the applied stress amplitude is 193 MPa, the fatigue life under the URM-LPBF condition is about 19% higher than that under the RM-LPBF condition and about 36% higher than that under the C-LPBF condition. The improvements in the comprehensive properties of the samples prove the feasibility of using USV to enhance LPBF forming. This study provides an innovative solution to the issue of powder polarization under ultrasonic action, thereby eliminating the anisotropy and enhancing the quality of LPBF, which can be a hopeful high performance strategy in metal powder AM fields.