激光冲击次数对高碳珠光体钢组织和显微硬度的影响

Effect of Laser Shock Processing Times on Microstructure and Microhardness of High Carbon Pearlitic Steel

采用激光冲击强化技术对原始组织为层片状珠光体的高碳钢进行表面强化处理,借助扫描电镜(SEM)、透射电镜(TEM)和显微硬度计等手段研究了激光冲击次数对高碳珠光体钢微观组织和硬度的变化规律。结果表明,原始珠光体组织经激光冲击后,渗碳体片层发生弯曲、断裂、球化,并且随着冲击次数的增加,冲击中心区域渗碳体球化程度加剧,溶解量也随之增加,过饱和的碳原子溶于铁素体基体中,导致其点阵常数增大。多次冲击后冲击中心区域材料表层的硬度从300HV(原始珠光体组织)分别增加至333HV(2次激光冲击),353HV(6次)。

High carbon pearlitic steel is processed by laser shocking processing （LSP）. The microstructure and hardness of high carbon pearlitic steel are examined using scanning electron microscope （SEM） and transmission electron microscope （TEM） and microhardness tester. The results show that the cementite lamellae is bent, fractured and spheroidized after multiple LSP impacts. With increase of LSP times, the spheroidization of the cementite lamellae is aggravating at the center of the laser spot, and the dissolution of the cementite is increased, supersaturated carbon atoms are dissolved in ferrite, leading to the increase of the lattice parameters. Moreover, the microhardness increases with increase of LSP times. After multiple LSP impacts, the microhardness at the center of the laser spot increases from 300 HV to 333 HV （2 LSP impacts）, 353 HV（6 LSP impacts）.