采用双光束激光修复碳钢零件的表面裂纹。裂纹修复区堆焊层与零件基体间存在一明显的白色熔合结合带 ,组织结构中存在联生的胞晶组织及树枝状、针状组织。枝晶为先析出相γ Ni,固溶有大量的Cu和Fe ;枝晶间隙除低熔点金属外 ,含有γ Ni,NiSi2 ,Cr3 Ni2 ,CrSi。修复区送料堆焊层的硬度明显高于碳钢基体的硬度 ,约在HV0 .2 40 0～HV0 .2 45 0 ,随后由堆焊层到过渡区逐渐降低 Using Double Beam Laser to Repair Surface Cracks of Carbon Steel Parts. There is a clear white fused joint between the surfacing layer and the part substrate in the crack repair area, and there are associated cell clusters and dendritic and needlelike structures in the microstructure. The dendrites are the first precipitated phase γ Ni and the solid solution contains a large amount of Cu and Fe. The dendritic interspace contains γ Ni, NiSi2, Cr3 Ni2 and CrSi in addition to the low melting point metal. The hardness of the repaired zone feeding surfacing layer is obviously higher than the hardness of the carbon steel matrix, about HV0.240 0 ~ HV0 .2 45 0, and then gradually decreased from the overlay to the transition zone