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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。
The microstructure evolution and hardness change of laser beam after eutectoid steel was treated by SEM, TEM and microhardness were studied. The results show that the ultrafine grain size of eutectoid steel can be achieved by one pass laser shock, the grain size of the equiaxed ferrite is about 0.8μm, and the shock wave produced by laser shock induces high strain rate Plastic deformation, cementite layer has good plastic deformation capacity, the center of the shock wave cementite lamella completely, cementite particle size of about 50nm, while the impact of the edge region of cementite ply bending mainly occurs , Kink and fracture. The plastic deformation leads to a large number of dislocations resulting in the hardness of the material surface in the central region of the shock wave being increased by about 20% compared with that before impact.