高温合金线性摩擦焊接头疲劳裂纹扩展有限元分析

To characterize the fatigue crack initiation and growth of linear friction welded superalloy joints in the fatigue environment and reveal the effect of crack growth on joint failure, this study investigates the fatigue crack growth behavior of the linear friction welded superalloy joint and its important influencing factors based on the finite element method. To study the internal causes of joint failure (holes, hard inclusions, and residual stresses), finite element models for the fatigue joints containing initial holes and inclusions with different geometric and location characteristics were established to study the sequence of crack initiation and propagation of the joints and classify important factors of crack growth. The results show that for the fatigue joints with initial holes and inclusions, cracks were initiated at the locations of the holes and inclusions. For the specimens with initial inclusions, the cracks grew in a "bypass" manner. For the joints with initial holes, the cracks were all propagated in a "crossing" manner. The locations of holes and inclusions had little effect on the crack initiation position and propagation mode. Crack initiation, propagation and specimen fracture occurred earlier with the increase of the size of holes and inclusions. The residual tensile stress of the joint accelerates the initiation and propagation of cracks, and the initiation and propagation time of cracks is positively correlated with the tensile stress.