PD3及BNbRE钢轨断裂韧性K_(IC)的研究

Study on the Fracture Toughness K_(IC) of PD3 and BNbRE Rails

钢轨是铁路轨道中非常重要的构件 ,直接关系到行车的安全。铁路不断提速对钢轨提出了越来越高的要求 ,在要求其有更高的使用寿命的同时 ,还要求其有更好的韧塑性 ,以保证铁路的安全。断裂韧性 KIC 是反应材料抵抗裂纹失稳扩张能力的力学性能指标 ,因而研究目前铁路较为普遍应用的PD3和BNbRE钢轨的断裂韧性KIC ,对提速线路、尤其是即将铺轨的时速 2 0 0km秦沈客运专线上钢轨的使用安全性非常重要。本试验通过对PD3及BNbRE钢轨在室温和 - 2 0℃时断裂韧性 KIC 的测定 ,分析了碳含量、钢种化学成分以及温度对断裂韧性的影响。同时还比较了两个钢种断裂韧性的不同和对温度的敏感性 ,相比之下 ,PD3在室温时的断裂韧性要稍高一些 ,而在 - 2 0℃时 ,BNbRE的断裂韧性要高一些 ,显示出BNbRE的断裂韧性KIC 随温度降低而下降更小 ,因而表现出对温度更不敏感。但是两个钢种的断裂韧性 KIC 都达到了铁道部颁发的“时速 2 0 0km客运专线 6 0kg·m- 1 钢轨暂行技术条件”

Rail is one of the most important component on railway track,and relates directly with the train operation safety.With the increasing of speed,much stricter requirements for rail is made.It is required to provide a longer service life and much higher toughness.Fracture toughness K IC  is a mechanical property parameter corresponding to the properties of track spreading resistance on materials.So the study on the fracture toughness K IC  of the widely used PD3 and BNbRE Rails is very important for the speed increasing safety,especially for the rails which will be installed on 200 km·h -1 Qin-Shen dedicated passenger railway.Based on the test of K IC  of PD3 and BNbRE rails under room temperature and -20 ℃,the influence of temperature and composition on fracture toughness and the difference of the two rails′ fracture toughness are compared.The fracture toughness of PD3 at room temperature is a little higher than BNbRE,and the toughness of PD3 at room temperature is a little higher than BNbRE,and the toughness of BNbRE at -20 ℃ is much higher.So the fracture toughness of the BNbRE has little sensitivity to temperature.The test reults show that the two rails′ fracture toughness K IC  are better than the standards set in the ″Provisional Technical Specifications of 60 kg·m -1 Rail for 200 km·h -1 Dedicated Passenger Railway″ which was issued by the Ministry of Railways.