CL60车轮钢喷丸强化的研究

Shot peening strengthening of CL60 wheel steel

对车轮用钢喷丸强化处理的可行性进行探讨。试验材料为CL60车轮钢，采用直径1mm的钢丸以45m／s的速度进行不同时间喷丸处理，分析其表层粗糙度、应力、组织和硬度随喷丸工艺的变化。试验结果表明：喷丸后的试样表层粗糙度均低于4．9μm，符合车轮服役规范；喷丸后试样表层会产生厚约为400μm的随深度变化的残余压应力，喷丸处理2min时最大应力可达762MPa；硬度随喷丸处理时间的增加逐渐提高，喷丸0．5h后表层硬度约为375HV，喷丸6h后表层硬度最高，可达到480HV，硬化层的厚度在喷丸1h时达到饱和，约为130μm；喷丸处理后，车轮钢表层渗碳体会产生变形细化、断裂、溶解，铁素体会明显细化，在喷丸处理3h时表层部分铁素体晶粒细化至70nm。喷丸处理1-3h可以在表层无损伤的情况下，有效提高硬度，为喷丸处理的最佳工艺。

The feasibility of shot peening strengthening treatment on the wheel steel was discussed. Shot peening treatment was used to the experimental material CL60 wheel steel with 1 mm steel shot at a speed of 45 m/s for different time. The changes of the surface roughness, stress, microstructure and hardness after shot peening treatment were analyzed. The results show that the surface roughness of the treated samples is lower than 4.9 ~m, which is in accord with the wheel service specification. After shot peening treatment, residual compressive stress of about 400 μm thickness changing along with depth was generated on the surface of the sample, the maximum compressive stress is 762 MPa after shot peening for 2 minutes. With increasing time of shot peening treatment, hardness increases gradually, the hardness of the surface is about 375HV after shot peening treatment for 0.5 h, and reaches the maximum 480HV when peened for 6 h, the thickness of the hardened layer increases at the beginning, and reaches the maximum after peened for 1 h, about 130 μm, then remains unchanged. After shot peening treatment, the cementite on the surface of wheel steel begins to deform and fracture, and finally dissolves into the ferrite, the ferrite on the surface refines significantly. The grain size of ferrite can be refined to 70 nm after peened for 3 h. The hardness of the wheel steel can be improved effectively without damage on the surface by shot peening for 1-3 h, which is considered as the optimum processing of shot peening strengthening on the wheel steel.