Investigation of thermal stability of residual stresses and microstructure of dual shot peened TC17 titanium alloy

This study investigates the thermal stability of surface residual stresses and microstructure in dual shot-peened (SP) TC17 titanium alloy after isothermal annealing at 350–500 °C for durations of 1 min to 2 h. Both surface residual stresses and microstrains relaxed with increasing temperature and annealing time, with the β-Ti phase exhibiting a faster relaxation rate than the α-Ti phase, likely attributed to its greater number of slip systems. The stress relaxation kinetics followed the Zener-Wert-Avrami model, with activation energies for stress relaxation ( ΔH σ ) of 101 kJ/mol and 69 kJ/mol for α-Ti and β-Ti, respectively. Despite significant stress relaxation, the dual SP treatment imparted remarkable microstructural stability, attributed to the formation of annealed nanotwins that effectively inhibit grain growth. • Thermostability of residual stress and microstructure of shot peened TC17 titanium alloy was studied. • Annealing generated nanotwin observed in annealed specimens. • The stress relaxation activation energies (ΔHσ) of α-Ti and β-Ti are 101 and 69 kJ/mol, respectively. • The microstructure possesses a high degree of thermal stability not exceeding 500 ℃.