【摘要】 采用SEM、TEM及显微硬度等方法研究了原始组织为层片状珠光体的共析钢激光冲击处理后的组织演变与硬度变化规律。结果表明:单道次激光冲击即可实现共析钢表层铁素体晶粒超细化,等轴铁素体晶粒尺寸约为0.8μm;激光冲击产生的冲击波诱发材料表层产生高应变速率的塑性变形,渗碳体层片具有较好的塑性变形能力,冲击波中心区域渗碳体层片球化完全,渗碳体颗粒粒径约为50nm,而冲击波边缘区域渗碳体层片主要发生弯曲、扭折和断裂;塑性变形导致大量位错的产生使得冲击波中心区域材料表层的硬度相比冲击前提高约20%左右。更多还原

【Abstract】 Microstructure evolution and variation in hardness of eutectoid steel with lamellar pearlite after laser shock processing(LSP)were investigated with SEM and TEM and micro-hardness test.The results show that the ferrite grains in top surface of the eutectoid pearlitic steel were ultra-refined after LSP for one pass.The average size of equiaxed ferrite grains was about 0.8 μm.The shock wave generated by LSP impact introduced plastic deformation with high strain rate in the top surface of eutectoid pearlitic steel.Cementite lamella exhibited good plastic deformation capacity during LSP.At the center of the laser shock wave cementite lamella were spheroidized completely and the size of the cementite particles were about 50 nm.At the edge of the laser shock wave bent,kink and fracture of cemetite lamella is observed.Hardness at the center of the laser shock wave in the top surface of eutectoid steel increased by 20% compared with that of un-LSP steel because of dislocation multiplication after laser shock processing.更多还原