6XN不锈钢与825合金的高周疲劳行为研究

Study on High-Cycle Fatigue Behavior of 6XN Stainless Steel and Alloy 825

采用旋转弯曲疲劳方法完成了6XN不锈钢与825合金在室温和550℃空气中的高周疲劳试验。结果表明:室温时,6XN不锈钢的耐久极限应力大于825合金的耐久极限应力,与静强度顺序一致;550℃高温时,试样氧化速率增加,材料疲劳寿命降低,6XN不锈钢的疲劳寿命下降趋势较大,耐久极限应力接近825合金的耐久极限应力;6XN不锈钢对温度更敏感,而825合金对应力循环次数更敏感;与经验公式比较,2种材料具有较好的抗高周疲劳性能;疲劳过程为裂纹源产生、扩展和断裂,最后断裂区具有韧窝特征。

The high-cycle fatigue （HCF） experiments of 6XN stainless steel and alloy 825 were conducted undér bending and rotating loads at room temperature （RT） as well as at 550℃ in air.The results indicate that the fatigue limited stress of 6XN at RT is higher than that of 825,which consistent with the order of their tensile strength.The oxidation rate of the specimen increased at 550℃,therefore the fatigue life of the specimen decreased,among them 6XN was more sensitive to high temperature with the larger decreasing tendency which make the fatigue limited stresses of the two alloys more closer at 550℃.While 825 is more sensitive to the stress cycles,both materials have good resistance to high cycle fatigue when comparing their experimental data with the calculated value from the empirical formula.The fracture morphology presents the areas of crack initiation,crack growth and fracture,and the fracture area has much dimples.