Collaborative improvement of macro-deformation and fatigue property for thin-walled parts in TA19 titanium alloy via a double-sided simultaneous ultrasonic surface rolling process

Abstract

To obtain thin-walled parts with superior geometric accuracy and fatigue resistance, a novel material surface processing paradigm, double-side simultaneous ultrasonic surface rolling process (DS-USRP), was proposed. The effects of the proposed process on the deformation suppression, surface modification, and fatigue improvement in thin-walled parts of the TA19 titanium alloy were also evaluated in this work. The average geometric deformation of thin-walled parts with the DS-USRP can decrease by ∼30 %. The fatigue life of thin-walled parts at elevated temperatures increased by a maximum of 60.9 times, and the corresponding fatigue strength was increased by 15.43 %. The surface integrity and microstructure of thin-walled parts also significantly change, and there is no failure risk associated with the superimposed effects of bilateral reinforcement. This study demonstrated that the synchronization of the compressive residual stress field evolution on both sides and the temporary increase in static stiffness could suppress the macro-deformation of the thin-walled parts during material surface processing. The improvement in fatigue-resistance at high temperatures is attributed to the low geometrical notch stress concentration and high compressive residual stress field. A moderate rolling intensity is essential to maximize the combined effect of the excellent surface quality and compressive residual stress field. Therefore, the proposed DS-USRP pattern is a promising and effective technique for the high-performance manufacturing of thin-walled parts in titanium alloys.