In-situ warm shot peening on Ti-6Al-4V alloy: Effects of temperature on fatigue life, residual stress, microstructure and mechanical properties

• Published in: Journal of alloys and compounds 2021-11, Vol.882, p.160701, Article 160701
• Main Authors: Lim, Su Hui, Zhang, Zheng, Seng, Debbie Hwee Leng, Lin, Ming, Teo, Siew Lang, Wei, Fengxia, Cheong, Augustine Kok Heng, Wang, Shijie, Pan, Jisheng
• Format: Article
• Language: English
• Subjects: Compressive properties; Crystallographic orientation mapping; EBSD; Fatigue life; Fatigue strength; Grain refinement; High temperature; Mechanical properties; Microstructure; Residual stress; Room temperature; Shot peening; Spring steels; Stress distribution; Stress relaxation; Temperature effects; Tensile stress; Thermal softening; Ti-6Al-4V; Titanium base alloys; Warm shot peening
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.160701

Shot peening (SP) is a matured surface enhancement technique to improve fatigue strength and fatigue lives of cyclically loaded metallic components at room temperature. In order to achieve enhanced beneficial effects beyond SP’s conventional performance, SP has been attempted at elevated temperatures or under tensile stress loading on spring steel with some success. In this work, SP on α/β Ti-6Al-4V alloys has been carried out when they were heated at elevated temperatures up to 400 °C. The effects of such in-situ warm SP on fatigue life of Ti-6Al-4V at different temperatures have been evaluated and correlated with respective development in compressive residual stress distribution, microstructure and hardness. The optimum in-situ warm SP condition was achieved at 100 °C after a trade-off between compressive residual stress relaxation and enhanced grain refinement, both of which are affected by thermal softening but to different degrees. [Display omitted] •α/β Ti-6Al-4V coupons were in-situ warm-shot-peened (WSP) at 32, 100, 200 and 300 °C.•Its fatigue performance was correlated with residual stress profile and microstructural changes.•WSP relaxed compressive residual stress (CRS) mildly at 100 °C but severely at 200 & 300 °C.•Surface grains were heavily refined after WSP at 100 °C, but agglomerated at 300 °C.•Optimum WSP is 100 °C for Ti64 with a trade-off between grain refinement and CRS relaxation.