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<p>This study reports on the development and characterization of a multi-layer SS316L wall created by Wire Arc Additive Manufacturing (WAAM) with a GTAW-based heat source. The research examined the microstructure, mechanical properties, corrosion behaviour, and wear performance at different heights of the build with a specific focus on the bottom and upper layers with respect to the differences in thermal management. Micro-hardness testing indicates an inhomogeneous hardness profile from the bottom to the top of the wall. The average hardness in the bottom area was greater in the build-up direction (206 HV) and the scanning direction (216 HV), compared to the upper area, i.e., 180 HV and 191 HV, respectively. The hardness in the upper layers was attributed to coarser grains formed due to a slower cooling rate, while finer grains and higher hardness were formed in the bottom layer as the samples cooled faster near the substrate, confirming the Hall–Petch relationship. The Ultimate Tensile Strength (UTS) values from tensile testing were found to be 644&#xa0;MPa for the samples built in the vertical direction and 624&#xa0;MPa for the samples built in the scanning direction, when compared to the wrought UTS material bearing 669&#xa0;MPa. The slight reduction in strength is mainly attributed to grain coarsening and repeated thermal cycling during deposition. Microstructural analysis showed a fine-grained austenitic matrix with lower retained δ-ferrite in the lower layers, while the upper layers showed a relatively coarser microstructure with higher retained δ-ferrite content because of lower thermal cycling. Electrochemical tests showed that the bottom portion of the wall had better corrosion resistance and a more stable passive film than the upper region. Similarly, the wear test results confirmed that the bottom region exhibited improved tribological behavior, such as a low coefficient of friction and a low specific wear rate compared to the upper layer. Overall, the results clearly showed the strong influence of thermal gradients on the microstructure, hardness, tensile response, corrosion resistance, and wear behaviour of WAAM-fabricated SS316L components.</p>

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Integrated study of microstructure, mechanical performance, corrosion resistance, and wear behaviour in SS-316L multi-layer walls fabricated by GTAW-based WAAM process

  • 期刊论文

  • 发表日期：

    2026年6月19日

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  • Zawed Alam,
  • Sudhansu Sekhar Panda,
  • Bhaskar Kumar

摘要

This study reports on the development and characterization of a multi-layer SS316L wall created by Wire Arc Additive Manufacturing (WAAM) with a GTAW-based heat source. The research examined the microstructure, mechanical properties, corrosion behaviour, and wear performance at different heights of the build with a specific focus on the bottom and upper layers with respect to the differences in thermal management. Micro-hardness testing indicates an inhomogeneous hardness profile from the bottom to the top of the wall. The average hardness in the bottom area was greater in the build-up direction (206 HV) and the scanning direction (216 HV), compared to the upper area, i.e., 180 HV and 191 HV, respectively. The hardness in the upper layers was attributed to coarser grains formed due to a slower cooling rate, while finer grains and higher hardness were formed in the bottom layer as the samples cooled faster near the substrate, confirming the Hall–Petch relationship. The Ultimate Tensile Strength (UTS) values from tensile testing were found to be 644 MPa for the samples built in the vertical direction and 624 MPa for the samples built in the scanning direction, when compared to the wrought UTS material bearing 669 MPa. The slight reduction in strength is mainly attributed to grain coarsening and repeated thermal cycling during deposition. Microstructural analysis showed a fine-grained austenitic matrix with lower retained δ-ferrite in the lower layers, while the upper layers showed a relatively coarser microstructure with higher retained δ-ferrite content because of lower thermal cycling. Electrochemical tests showed that the bottom portion of the wall had better corrosion resistance and a more stable passive film than the upper region. Similarly, the wear test results confirmed that the bottom region exhibited improved tribological behavior, such as a low coefficient of friction and a low specific wear rate compared to the upper layer. Overall, the results clearly showed the strong influence of thermal gradients on the microstructure, hardness, tensile response, corrosion resistance, and wear behaviour of WAAM-fabricated SS316L components.