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研究了冷作模具LD钢经不同工艺参数激光熔凝处理后的显微组织及性能。结果表明,激光功率P=3500 W,扫描速度v=20 mm/s,光斑直径d=5 mm时,处理效果较为理想。由表及里依次为熔凝层、淬火层、热影响层和基体。熔凝层又依次分为表层等轴晶区,柱状晶区和等轴晶+胞状晶区。等轴晶区和柱状晶区原有的带状、块状碳化物全部溶解,胞状晶区原有的碳化物基本保持原状,新晶粒明显细化并均匀分布。硬化层总深度可达1.0 mm;平均硬度可提高15%左右,耐磨性和耐腐蚀性显著提高。如果能量密度过大,在熔凝层容易产生微裂纹甚至宏观裂纹,破坏材料性能。
The microstructure and properties of cold-working LD steel after laser melting treatment under different process parameters were studied. The results show that the laser beam power P = 3500 W, the scanning speed v = 20 mm / s, the spot diameter d = 5 mm, the treatment effect is quite satisfactory. From the table followed by the fused layer, quenched layer, heat affected layer and the substrate. Melting layer and then into the surface equiaxed zone, columnar and equiaxed zone + cell crystalline zone. Equiaxed zone and columnar zone of the original ribbon, massive carbides dissolved, cell-like crystal area of the original carbide remained unchanged, the new crystal was significantly refined and evenly distributed. The total depth of the hardened layer can reach 1.0 mm; the average hardness can be increased by about 15%, and the abrasion resistance and corrosion resistance are remarkably improved. If the energy density is too large, easy to produce micro-cracks in the melt layer or macro-cracks, undermining the material properties.