【摘要】 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。更多还原

【Abstract】 Microstructure and properties of LD cold work die steel were studied by laser surface melt-solidifying with different process parameters.The results show that when laser power is 3500 W,scanning speed is 20 mm/s,and the light spot diameter is 5 mm,laser treatment effect is more ideal.The surface of the steel from outside to inside is melt-solidified layer,quenched layer,heat affected layer and the substrate in turn.The melt-solidified layer can also be divided into surface equiaxial grain zone,columnar grain zone and the fine equiaxial grain + cellular grain zone.The original ribbon or blocky carbides in the equiaxial grain zone and columnar grain zone are dissolved,and the carbides in the cellular grain zone keep original shape,the new grains are refined obviously and uniform distribution.The total depth of the strengthening layer center can reach to 1.0 mm,the average microhardness can be increased by about 15%,and the wear resistance and corrosion resistance are also improved significantly.If the energy density is too large,the microcracks even macro cracks are easy to initiate in the melt-solidified layer,then destroy the material performance.更多还原