Study On The Improvement Of Fatigue Properties Of Titanium Alloy With ESD Fireproof Layer Processed By Ultrasonic Impact

Titanium alloys are widely used in various parts of aero-engines because of their excellent properties,but titanium alloys in the working environment of aircraft engines are prone to titanium fire failures.At present,in the titanium fire prevention technology at home and abroad,the preparation of fireproof coatings on the surface of titanium alloy has obvious advantages,but it will reduce the fatigue performance of titanium alloy components.In this study,ultrasonic impact was used to treat the surface of titanium alloy components with electro spark deposition(ESD)fireproof layer,and the fatigue performance of titanium alloy components with ESD fireproof layer prepared on the surface was improved.The main research contents and conclusions of this study are as follows:Based on the motion process of ultrasonic impact,the theoretical calculation and analysis of the surface roughness and residual stress distribution of the material after ultrasonic impact treatment were carried out,and the design of the ultrasonic impact gun was improved.A three-axis automatic ultrasonic impact test system is designed and built.The system mainly includes the ultrasonic impact section and the mobile control section.The system controls the movement of the ultrasonic impact gun through the mobile control mechanism to accomplish the automatic processing of ultrasonic impact.According to the design drawings,a three-axis automatic ultrasonic impact system was built and verified by experiments.The results showed that the surface roughness of the titanium alloy samples prepared with ESD fireproof layer after ultrasonic impact treatment was greatly reduced,which effectively improved the surface quality of the samples.Through the research on the process parameters of ultrasonic impact treatment,it is concluded that the process parameters of ultrasonic impact treatment are feed speed 2mm/s,output amplitude 32μm and pre-pressure 60 N,respectively.Under these process parameters,the surface quality of titanium alloy samples prepared with ESD fireproof layer after ultrasonic impact treatment shows the best performance.The fatigue properties and fireproof properties of titanium alloy samples prepared with ESD fireproof layer before and after ultrasonic impact treatment were tested.The results show that the fatigue properties are improved when the fireproof properties remain unchanged.