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<p>The high-pressure torsion (HPT) process is one of the most powerful methods of severe plastic deformation, capable of significantly refining the microstructure and altering the functional properties of high-strength aluminum alloys. In this work, the effects of HPT on the microstructure, residual stresses, hardness, and damping characteristics of the AA7075 alloy were comprehensively studied. Microstructural investigation revealed that the average grain size of the starting material was around 95&#xa0;µm, but after HPT, it decreased to ~ 6.1&#xa0;µm, indicating continuous dynamic recrystallization. The secondary-phase particles were fragmented and uniformly distributed, as observed by SEM. The lattice strain was evident from the broadening of the XRD peaks. High compressive residual stresses were found near the surface (~ − 600&#xa0;MPa), whereas at greater depths the stresses were tensile due to strain gradients. Microhardness rose about 35–40%, i.e., from ~ 170–177 VHN to ~ 229–245 VHN, due to grain size reduction and dislocation density increment. Dynamic mechanical analysis showed a dramatic improvement in damping capability (~ 0.012–0.062 to ~ 0.032–0.09 over 1–30&#xa0;Hz) due to grain boundary sliding, dislocation hysteresis, and residual stresses.</p>

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Structure–Property Relationships in High Pressure Torsion-Processed AA7075 Alloy: A Combined Microstructural and Functional Analysis

  • 期刊论文

  • 发表日期：

    2026年5月14日

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  • Kadapa Vijaya Bhaskar Reddy,
  • K. Santarao,
  • Sd. Abdul Kalam,
  • M Udaya Kıran,
  • Yadluri Ravi Kishore,
  • G. Uma Maheswara Rao,
  • K. Rajesh

摘要

The high-pressure torsion (HPT) process is one of the most powerful methods of severe plastic deformation, capable of significantly refining the microstructure and altering the functional properties of high-strength aluminum alloys. In this work, the effects of HPT on the microstructure, residual stresses, hardness, and damping characteristics of the AA7075 alloy were comprehensively studied. Microstructural investigation revealed that the average grain size of the starting material was around 95 µm, but after HPT, it decreased to ~ 6.1 µm, indicating continuous dynamic recrystallization. The secondary-phase particles were fragmented and uniformly distributed, as observed by SEM. The lattice strain was evident from the broadening of the XRD peaks. High compressive residual stresses were found near the surface (~ − 600 MPa), whereas at greater depths the stresses were tensile due to strain gradients. Microhardness rose about 35–40%, i.e., from ~ 170–177 VHN to ~ 229–245 VHN, due to grain size reduction and dislocation density increment. Dynamic mechanical analysis showed a dramatic improvement in damping capability (~ 0.012–0.062 to ~ 0.032–0.09 over 1–30 Hz) due to grain boundary sliding, dislocation hysteresis, and residual stresses.