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研究40Cr在激光单道熔凝和叠道熔凝下材料表面显微组织分布特征,表面硬度分布规律和残余应力状态,结果显示单道激光熔凝的强化层组织由表层熔化区、亚表层相变硬化区及与基体相连的高温回火区组成,最大残余应力为拉应力,出现在熔凝带中心,在熔化带边缘为压应力,在热影响区为拉应力:叠道激光熔凝试件表面显微组织和硬度分布的差异在回火软化区和二次淬硬区。。叠道扫描的残余应力要比单道激光熔凝的小,新的熔凝带对前道熔凝带施加了应力并产生了韧化作用。
The microstructure distribution, surface hardness distribution and residual stress state of 40Cr were studied under single laser fusion and lapping fusion. The results show that the microstructure of 40Cr laser melted layer consists of surface melting zone, sub-surface phase Hardened zone and the high temperature tempering zone connected to the base body, the maximum residual stress is tensile stress, appears in the center of the melting zone, at the edge of the melting zone is compressive stress, tensile stress in the heat affected zone: Stack laser fusion test The difference of surface microstructure and hardness distribution between temper softening zone and secondary hardening zone. . The residual stress in lapping scanning is smaller than that of single lasers, and the new lapping zone exerts stress and toughening on the former lapping zone.