超声冲击对钢轨钢组织与性能的影响

The Influence of the Ultrasonic Impact on the Microstructure and Properties of Rail Steel

利用HJ-Ⅱ型超声冲击机对U70钢轨的表面进行超声冲击处理。在超声冲击机输出能量一定的前提条件下,采用6360LA型扫描电镜观察分析不同超声冲击时间下钢轨表面组织的变化,研究经过超声冲击处理后钢轨表面硬度和耐磨性的变化。实验结果表明,超声冲击对钢轨表面能够起到明显的强化作用,钢轨表面的硬度和耐磨性显著提高,而且随着超声冲击时间的延长,钢轨表面的硬度和耐磨性越来越好。与未经超声冲击处理的钢轨试样相比,在超声冲击时间分别为3,6,15和30 min的实验条件下,U70钢轨的表面硬度分别提高了23.6%,32.9%,43.1%和48.1%;耐磨性分别提高了30.6%,32.7%,42.9%和57.1%。

The ultrasonic impact treatment on the surface of U70 rail steel was carried out by using HJ-Ⅱ ultrasonic impact machine. Under the condition of the stated output energy of the impact machine, the influence of different impact time on the surface microstructure of rail steel was observed and analyzed with 6360LA type SEM （scanning electron microscope）, and the hardness and the wear resistance of the impacted surface was also researched before and after the impact treatment. The experimental results indicate that the surface strength of rail steel can be improved evidently by using ultrasonic impact treatment. The surface microstructure of the rail steel can be refined and the hardness and wear resistance of the impact layer are significantly improved through the ultrasonic impact technology. The longer is the impact time, the greater increasing range of hardness and wear resistance will be. Compared to the rail sample without impact treatment, the rail surface hardness is increased by 23.6%, 32.9%, 43.1% and 48.1% respectively, and the wear resistance is also increased by 30.6%, 32.7%, 42.9% and 57.1% respectively, when the impact time is 3, 6, 15 and 30 min respectively.