Effects of Deep Rolling on the Microstructure Modification and Fatigue Life of 35Cr2Ni4MoA Bolt Threads

Stress concentration on a bolt thread, resulting from its own special shape, poses threat to the fatigue strength of bolt, which directly affects safety and reliability aircraft. In this paper, deep rolling was applied thread improve resistance. The properties plastic deformation layer, including surface morphology, microstructure, hardness, residual stress, as well life were characterized by means SEM, white light interferometer, EBSD, tests. results showed that roughness bottom reduced 0.255 ?m, layer about 300 ?m in depth formed after rolling. A more compact streamlined fibrous composed refined grains, with increased dislocation density hardness decreased tensile layer. bolts 113%, evidencing comprehensive result these microstructure modifications.