Study on Residual Stress Relief and Shape Accuracy Retention of Titanium Alloy Parts

Residual stress relief tests are carried out on typical TC4 R state titanium alloy commonly used in spacecraft structural products by vacuum stress relief annealing, cryogenic treatment, and high and low temperature cyclic heat treatment. X-ray diffraction method is used to measure residual stress in the specimens, and the average residual stress relief rates inside and in the surface of the treated specimens are calculated. Finally, the shape accuracies of the treated specimens are tested, and the effectiveness of various heat treatment methods in maintaining shape accuracy is verified. The results show that the vacuum stress relief annealing is the most effective, followed by cryogenic treatment, and that the effectiveness of high and low temperature cyclic heat treatment is the lowest. The average residual stress relief rate is strongly positively correlated with the shape accuracy retention. Of all the specimens treated by different methods, the average residual stress relief rates in the internal/surface of specimens treated with the combination of vacuum stress relief annealing, cryogenic treatment, and high and low temperature cycle heat treatment in queue are the highest, and their shape accuracy retention the best, those of the specimens treated with cryogenic treatment and high and low temperature cycle heat treatment come in second, and those of the specimens only treated with high and low temperature cyclic heat treatment rank last.