Residual stress of belt polishing for the micro-stiffener surface on the titanium alloys

Abstract

Titanium alloys are widely used in the key parts of aero-engine, such as blade, blisk and so on, and the belt polishing process is proved to be a good method to creating optimal surface integrity to improving the fatigue life and service performance for titanium alloys parts. The method of micro-stiffener belt polishing was presented, based on the influence rule of thin-plate stiffener on the bending life and the principle of micro-crack, to forming characteristically and clearly surface texture to further improving the fatigue life with new belt polishing method. This paper provides a comprehensive characterization of residual stresses produced in micro-stiffener belt polishing for heat-resistant titanium alloys bearing steel using aluminum oxide abrasive belt. There are two method to analyzing the residual stresses generated by this method: the X-ray projector was used to measure the surface residual stress to revealing the formation rule of residual stress with different belt polishing parameters (reciprocating frequency, feeding speed and contact force), and a finite element model of the belt finishing operation in order to bring an further understanding the belt polishing process and the residual stress distribution in different depth. The results show that, the contact force is the main parameters to influencing the forming of residual stress, and the same time, the bigger residual stress would be obtained under the conditions of smaller feeding speed and faster reciprocating frequency, the influenced layer thickness of residual stress is nearly 10μm, and the maximum residual stress is 1.2μm under the surface. Therefore, the new method can be used to improve the surface residual stress of titanium alloy parts.