高超载比超载对Q345钢的疲劳性能的影响

Effect of Overload with High Overload Ratio on Fatigue Properties of Q345 Steel

采用Q345钢制作成紧凑拉伸试样,并在裂纹萌生后进行超载。通过疲劳裂纹扩展试验,研究高超载比超载对疲劳裂纹扩展速率的影响,分析其延寿机理。研究发现:较高的超载比使试样引入了残余压应力,使得有效应力强度因子降低至应力强度因子门槛值附近。可以降低疲劳裂纹扩展速率,抑制裂纹扩展,延长试样的疲劳寿命,通过此方法提高了含裂纹结构的使用寿命。

A compact tensile specimen was made of Q345 steel and overloaded after the crack initiation.Through the fatigue crack growth test,the influence of overload with high overload ratio on fatigue crack growth rate is studied,and its life extension mechanism is analyzed.It is found that the high overload ratio leads to the introduction of residual compressive stress,which reduces the effective stress intensity factor to near the threshold value of stress intensity factor.The fatigue crack growth rate can be reduced,the crack growth can be restrained,and the fatigue life of the specimen can be prolonged.The service life of the structure with cracks can be prolonged by this method.