重载铁路钢轨的伤损及预防对策研究

Research on the Rail Damages and the Preventive Countermeasures in Heavy Haul Railways

通过对重载铁路钢轨伤损的现场调查分析,确定出钢轨伤损的主要类型和规律,在此基础上提出了预防对策措施并进行了试验验证。结果表明:①在半径小于1 200 m的曲线上铺设轨面硬度大于370 HB的含铬热处理钢轨(U77 MnCr和PG4)、采用每天1次固体润滑并设置欠超高,可以减少钢轨的严重侧磨;②热塑性弹性体垫板可以增加轨道弹性,减少轨道动应力和钢轨的疲劳核伤;③在减少所用钢轨表面脱碳层深度和钢中夹杂物的基础上及时进行钢轨打磨,可有效抑制钢轨轨距角剥离掉块伤损的发展;④虽然热轧轨出现的剥离掉块深度较浅,但会在轨面外侧出现严重的深层肥边掉块,影响钢轨的安全使用,因此,重载铁路曲线下股仍应铺设高强度的热处理钢轨;⑤在优化焊接工艺和提高接头内部质量的基础上,对焊接接头采用焊后再淬火,以提高接头轨面的硬度,从而明显减少焊接接头轨面的低塌和焊接接头的伤损。

The main types and the development trend of rail damages have been determined by field investigation in the rail damage of heavy haul railways. On this basis, the countermeasures have been put forward and validated by tests. Results show that： （1） on the curves with the radius no greater than 1200 m, severe side abrasion of rails can be controlled by paving heat treated rails with Cr elements and the hardness of the rail surface greater than 370 HB （U77MnCr and PG4）, by lubricating with solid lubrication once a day, and by setting up appropriate deficient superelevation. （2） Thermal-plastic tie plates can increase track elasticity and reduce the dynamic stresses and eventually decrease the oval flaws resulted from fatigue. （3） The growth of the tread shelling on the rail corner can be mitigated by timely rail grind- ing on the basis of decreasing the decarbonized depth in tread layer and nonmetal inclusions of rail material. （4） It is suggested that the hardened premium steel should be applied to the lower rail of the heavy haul railway because deep crushing may produce on the railhead which affects the running safety even though the shelling is relatively shallow. （5） Welding defects especially the crushing on the railhead at the welding joints can be markedly reduced by optimizing the welding process to improve the joint quality and adding re-quenching after welding so as to augment tread hardness.