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<p>A gradient nanostructured layer was fabricated on the surface of TA15 (Ti-6Al-2Zr-1Mo-1V) alloy (produced by selective laser melting) using severe shot peening (SSP). This study focuses on the evolution of the microstructure and the mechanism of grain refinement in TA15 titanium alloy during SSP treatment. Transmission electron microscopyand Rietveld refinement methods were employed. The residual stress and microhardness variations with depth were also characterized. The results show: (1) At the initial stage of deformation, plastic deformation is primarily accommodated through twinning and dislocation slip. (2) As the strain increases, twinning disappears, and dislocations interact to form tangles. Some dislocations annihilate and rearrange into subgrain boundaries, subdividing the original grains into subgrains. (3) With continued dislocation activity, the subgrain size decreases until nanocrystals are formed through the dynamic rotational recrystallization. SSP introduced compressive residual stress (CRS) in the near-surface layer of the material, with the maximum CRS of approximately −1141&#xa0;MPa observed in the subsurface layer. It also induced work hardening, increasing the surface hardness to approximately 479&#xa0;HV. However, the surface roughness increases, leading to a slight deterioration in surface quality.</p>

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Microstructure Evolution and Residual Stress Redistribution in Selective Laser Melted TA15 Titanium Alloy Under Severe Shot Peening Treatment

  • 期刊论文

  • 发表日期：

    2025年7月29日

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  • Ang Yin,
  • Wenbo Li,
  • Chengxi Wang,
  • Vincent Ji,
  • Chuanhai Jiang

摘要

A gradient nanostructured layer was fabricated on the surface of TA15 (Ti-6Al-2Zr-1Mo-1V) alloy (produced by selective laser melting) using severe shot peening (SSP). This study focuses on the evolution of the microstructure and the mechanism of grain refinement in TA15 titanium alloy during SSP treatment. Transmission electron microscopyand Rietveld refinement methods were employed. The residual stress and microhardness variations with depth were also characterized. The results show: (1) At the initial stage of deformation, plastic deformation is primarily accommodated through twinning and dislocation slip. (2) As the strain increases, twinning disappears, and dislocations interact to form tangles. Some dislocations annihilate and rearrange into subgrain boundaries, subdividing the original grains into subgrains. (3) With continued dislocation activity, the subgrain size decreases until nanocrystals are formed through the dynamic rotational recrystallization. SSP introduced compressive residual stress (CRS) in the near-surface layer of the material, with the maximum CRS of approximately −1141 MPa observed in the subsurface layer. It also induced work hardening, increasing the surface hardness to approximately 479 HV. However, the surface roughness increases, leading to a slight deterioration in surface quality.