Study on X-Ray Parameter and Fracture Mechanics Parameter on Fatigued Fracture Surface under Variable Loading

摘要

The relation formula between X ray parameter eppsilon_y and the fracture mechanics parameter K_(max) on the fracture surface under variable loading is examined. CT specimens made of cyclic softening material HW685 steel and cyclic hardening material SS400 steel were tested on fatigue crack propagation test. The fracture surfaces were analyzed by X-ray fractography, and the parameter eppsilon_y was determined, then the hardness at sub-surface of the fracture surface were measured, and estimated the yield stress (sigma_y ) at the region of crack tip. The relation formula between eppsilon_ y and K_(max) is proposed, and the experimental results have a good agreement with the proposed formula.