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利用液压伺服疲劳实验机研究了400 MPa级板带在对称循环应力下的高周疲劳性能,测量了S-N曲线,确定了应力幅低于疲劳强度时疲劳寿命与应力幅之间的关系式;用扫描电镜观察该钢的疲劳断口,分析了疲劳断裂特点;在透射电镜下观察了断口附近的微观组织,并对其疲劳断裂机理进行了分析,结果表明:疲劳裂纹起源于表面驻留滑移带挤出脊、侵入沟或表面缺陷,裂纹源扩展最终导致断裂。
The high-cycle fatigue behavior of 400 MPa plate under symmetrical cyclic stress was studied by hydraulic servo fatigue tester. The SN curve was measured and the relationship between fatigue life and stress amplitude was obtained when the stress amplitude was lower than the fatigue strength. The fatigue fracture of the steel was observed by scanning electron microscope (SEM) and the fatigue fracture characteristics were analyzed. The microstructure of the steel was observed under transmission electron microscope and the fatigue fracture mechanism was analyzed. The results show that the fatigue crack originated from the surface resident slip band Extruding ridges, invades ditch or surface defects, the source of crack propagation eventually lead to fracture.