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通过试验 ,分析研究了 4 5钢激光相变强化梯度分布的显微组织特征以及原始组织对 4 5钢激光相变强化梯度组织及其显微硬度的影响。通过对不同原始组织激光相变强化效果的对比分析 ,指出原始组织越细小弥散 ,成分越均匀 ,缺陷密度越高 ,材料的临界硬化温度越低 ,越有利于激光相变强化。在相同的激光处理工艺参数下 ,原始组织为淬火高温回火态时 ,激光相变强化的效果最显著 ,正火态次之。淬火回火态的激光相变强化比退火态具有更大的硬化层深度及更高的显微硬度
The effects of the original microstructure on the laser gradient transformation microstructure and the microhardness of 45 steel were analyzed by experiments. By comparing and analyzing the laser phase transformation strengthening effect of different primary structures, it is pointed out that the finer the original structure, the more uniform the composition and the higher the defect density, the lower the critical hardening temperature of the material, the more favorable to the laser phase transformation strengthening. Under the same laser processing parameters, the effect of laser phase transformation strengthening is the most obvious when the original microstructure is quenched and tempered at high temperature, followed by the normalized state. Quenched and tempered laser phase transformation strengthened annealed state has a greater hardened depth and higher microhardness