高速铁路新材料

为探究踏面制动方式对货车车轮踏面状态的影响，针对直径为915 mm和840 mm的货车车轮进行踏面制动台架试验，对比分析制动前后车轮踏面形貌、硬度和浅表层残余应力的变化。结果表明：在相同制动工况下，直径915 mm车轮踏面未出现明显热斑，而直径840 mm车轮踏面出现约20处热斑，这与车轮热容量以及闸瓦材料特性有关，而且由制动热产生的热斑会导致硬度下降。此外，试验验证了踏面制动过程中车轮踏面浅表层残余应力会发生拉应力和压应力之间的转变，为车轮热裂纹机理研究提供了试验依据及技术支持。

In order to explore the influence of tread braking methods on the tread state of railway freight car wheels, wheels with diameters of 915 mm and 840 mm were conducted tread braking bench tests, and the changes in tread morphology, hardness and shallow-layer residual stress were compared and analyzed. The research results show that after experiencing the same braking conditions, there were no obvious hot spots on the 915 mm diameter wheel tread, while there were about 20 hot spots on the 840 mm diameter wheel tread, whose reason is related to the wheel's thermal capacity and the material properties of the brake shoes, and the hot spots generated by braking heat will cause a decrease in tread's hardness. In addition, from the perspective of experimental testing, it has been verified that there exists a transition between tensile stress and compressive stress the residual stress on the wheel tread's shallow-layer during the tread braking process, providing experimental and technical support for the study of the wheel thermal cracking mechanism.