无限冷硬铸铁轧辊的激光表面改性

Laser Surface Modification of Indefinite Chilled Cast-Iron Roller

轧辊作为轧制过程中金属变形的直接工具，其质量和使用寿命至关重要。同时轧辊也是冶金企业的主要消耗部件，在轧钢生产成本中占很重的比例。使用Cr2C3＋NiCr粉末，利用激光熔覆技术对镍铬无限冷硬铸铁轧辊进行了表面改性，旨在大幅度提高轧辊硬度及使用寿命。研究表明，熔覆层与基材呈良好的冶金结合，相对于基材微观组织，熔覆层组织更为致密；基材和熔覆层的平均硬度分别为506HV和1137HV，熔覆层的硬度提高了25％，熔覆层的耐磨性能明显提高。激光熔覆层内形成的微裂纹主要由结晶裂纹和高温低塑性裂纹组成，通过二次扫描和调整粉末化学成分可有效地减少微裂纹的形成。

As the direct tool of metal deforming in rolling, the quality and operational life span of mill roll are of high significance. Mill roll is the main consumption component with a high ratio in steel rolling production costs, In this paper, the indefinite chilled cast-iron roller is surface-modified by laser cladding, using Cr2 C3 and NiCr powder. The results indicates that, the cladding layer and base materials are a good metallurgical bond, and the microstructure of cladding layer is finer than base materials. The average microhardnesses of base materials and cladding layer are 506 HV and 1137 HV, respectively. Compared with the base material hardness, cladding layer hardness increases by 25 %, so the wear resistance of the cladding layer is significantly improved. Microcrack in cldding layer includes solidification crack and low plasticity crack, and the microcrack is effectively decreased by the secondary scanning and adjusting chemical composition of the oowder.