残余应力对U75V重轨钢疲劳裂纹扩展速率的影响

• 作 者: 王慧军 陈林 郭飞翔 陈昆宇 宿皓 刘志敏
• 机 构: 内蒙古科技大学材料与冶金学院,
• 出 处: 金属热处理
• 发表日期: 2017年06期
• 关键词: 残余应力 U75V 重轨钢 残余压应力 断口形貌 疲劳辉纹 疲劳裂纹 裂纹扩展速率 裂纹尖端 应力强度因子

通过残余应力测试仪Stress3000测试了不同工艺处理U75V重轨钢表面残余应力,利用Sinco Tec疲劳试验机研究了残余应力对疲劳裂纹扩展速率的影响,并对疲劳断口形貌进行了观察。结果表明:不同工艺处理U75V重轨钢表面残余应力均为压应力,淬火态试样表面平均残余应力大于轧态试样;随退火温度升高和退火时间延长,试样表面残余应力下降明显。随表面残余压应力的增大,疲劳裂纹常数m值逐渐减小,即裂纹扩展速率随着表面残余压应力的增加而减小。断口形貌观察发现表面残余压应力较大时,断口疲劳辉纹更为细小,有利于降低表面疲劳裂纹扩展速率。

The residual stress on the surface of U75V heavy rail steel was tested by Stress 3000, and the effect of residual stress on the fatigue crack growth rate was investigated by Sinco Tec fatigue tester. The appearance of fatigue fracture was also observed. The results show that the residual stress on the U75V heavy rail steel is compressive, and the average residual stress on the quenched sample surface is larger than that on the rolled sample. With the increase of annealing temperature and annealing time, the residual stress on the sample surface obviously decreases. As the residual compressive stress increases, the value of the fatigue crack growth rate m decreases gradually, that is to say, the crack propagation rate decreases with the increase of residual compressive stress on the surface. Fracture morphology observed surface residual compressive stress is larger, the fatigued fracture finer finer, help to reduce the surface fatigue crack growth rate.