高镍铬无限冷硬铸铁轧辊表面激光合金化的研究

将激光合金化技术应用于高镍铬无限冷硬合金铸铁轧辊,利用OM,SEM,显微硬度计和X射线衍射仪对激光合金化层的显微组织、成分、截面显微硬度分布和物相进行分析研究.结果表明,合金化层表面平整,与基体形成了冶金结合,部分区域存在裂纹.在激光功率、光斑直径、搭接率一定的条件下,合金化层厚度随扫描速度变化不大;裂纹率随速度增加而增加;合金化层硬度随速度的增加先提高后降低.当激光功率为7.2 kW,光斑直径为0.8~3 mm,搭接率为33.3%时,最佳扫描速度为11 m/min.此时,合金化层平均厚度为0.287 5 mm,平均显微硬度为1 001 HV0.05,是基体材料(656 HV)的1.53倍.

Research on Laser Alloying of High-Ni-Cr Infinite Chilled Cast Iron Roller

The laser alloying technique was applied to the high-Ni-Cr infinite chilled cast iron roller coated with nano-carbide ceramics. The microstructural morphology, composition, cross-sectional microhardness distribution and the phases of the alloyed coating were analyzed by OM, SEM, microhardness tester and XRD. The results revealed that the flat alloyed coating combines metallurgically with the substrate with some cracks found in part. Under conditions that the laser power, spot diameter and overlap ratio remain unchanged, the thickness of the coating changes slightly with varying scanning speed, but the rate of cracks increases with increasing speed and the hardness of alloyed coating increases then decreases with increasing scanning speed. The optimal scanning speed is 11 m/min when the laser power is 7.2 kW, beam diameter 0.8-3 mm and overlapping rate 33.3%. At the moment, the average thickness of alloyed coating is 0.2875 mm with an average microhardness up to 1001 HV0.05, i.e. about 1.53 times as high as that of the substrate of 656 HV.