高速道岔钢轨轨底材质疲劳性能试验研究

Experimental Study on Fatigue Properties of Rail Bottom Material of High Speed Turnout

针对高速铁路道岔钢轨轨底萌生疲劳裂纹而导致轨件断裂的问题,以高速道岔R350HT钢轨为对象,从轨底中部硬度最低的位置取样,分别开展轨底材质拉伸试验、疲劳极限试验、疲劳裂纹扩展试验以及断裂韧性试验,为阐明高速道岔轨底疲劳伤损机理及轨件服役寿命预测提供依据。结果表明:采用升降法得到道岔R350HT钢轨轨底材质的疲劳极限为447.1 MPa,所有试样均失效于表面裂纹萌生;轨底材质裂纹扩展速率为da/d N=1.89×10^(-10)ΔK^(4.18);室温(25℃)和低温(-10℃)环境下测试得到的断裂韧性接近,轨底材质在-10℃没有呈现低温脆性特征。

Aiming at the problem of rail fracture caused by fatigue crack initiation at the rail bottom of high peed railway turnout,the rail bottom material tensile test,fatigue limit test,fatigue crack propagation test and fracture toughness test were carried out from the position with the lowest hardness in the middle of the rail bottom by taking high speed turnout R350HT rail as the object,providing a basis for clarifying the fatigue damage mechanism of the rail bottom of high speed turnout and predicting the service life of the rail.The results show that the fatigue limit of the rail bottom material of the turnout R350HT rail obtained by the lifting method is 447.1 MPa,and all samples fail at the surface crack initiation.The crack growth rate of rail bottom material is da/d N=1.89×10^(-10)ΔK^(4.18).The fracture toughness measured at room temperature(25℃)and low temperature(-10℃)is similar,and the rail bottom material does not exhibit low-temperature brittleness at-10℃.