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研究目的:目前我国主要的几条重载铁路铺设使用了当今世界上断面最大的75 kg/m钢轨,国外重载铁路发达的国家则大量使用美国铁路保养协会钢轨技术条件(AREMA-2004)中规定的136RE(68 kg/m)断面的钢轨,且较为成熟。因此开展68 kg/m钢轨的试验研究,可为我国重载铁路钢轨的铺用提供更多的选择,对发展我国重载铁路运输具有重要的意义。研究结论:热轧钢轨室温抗拉强度为1 080 MPa,轨顶面硬度达到300 HB;成品钢轨中的氢含量为0.5×10-4%,氧含量为12.3×10-4%;轨头踏面及轨角处的显微组织为片状珠光体及少量铁素体;轨底最大残余拉应力为200.2 MPa;-20℃断裂韧性KIC为32.5MPa.m1/2;裂纹尖端强度因子ΔK=10 MPa.m1/2及13.5 MPa.m1/2时疲劳裂纹扩展速率da/dN分别为9.55 m/Gc和31.98 m/Gc。由以上试验研究结果可知,我国68 kg/m热轧钢轨的各项性能指标均达到了《68 kg/m钢轨暂行技术条件》的要求,可以上道试铺。
Research purposes: At present, some of the major heavy-haul railways in our country use the 75 kg / m rails with the largest cross section in the world today, while the countries with developed heavy haul railways make extensive use of RAEM rail technology conditions (AREMA-2004) The provisions of the 136RE (68 kg / m) section of the rail, and more mature. Therefore, the experimental study on 68 kg / m rail can provide more choices for the laying of heavy-haul railroad rails in our country and is of great significance for the development of heavy haul railway in our country. The conclusions are as follows: The tensile strength of hot-rolled rail is 1 080 MPa at room temperature, the hardness of rail top surface is 300 HB; the hydrogen content of finished rail is 0.5 × 10-4% and the oxygen content is 12.3 × 10-4% And the corner of the microstructure of flake pearlite and a small amount of ferrite; the maximum residual tensile stress at the rail bottom of 200.2 MPa; -20 ℃ fracture toughness KIC 32.5MPa.m1 / 2; crack tip strength factor ΔK = 10 The fatigue crack growth rates da / dN at MPa.m1 / 2 and 13.5 MPa.m1 / 2 are 9.55 m / Gc and 31.98 m / Gc, respectively. From the above experimental results, we can see that all the performance indexes of 68 kg / m hot-rolled rails in our country meet the requirements of “Interim technical conditions of 68 kg / m rails” and can be tested on the road.