扫描速度对硅钢表面激光熔覆层组织和硬度的影响

Effect of Scanning Speed on Microstructure and Microhardness of Laser Cladding of Silicon Steel

在低硅钢表面激光熔覆Fe-Si粉末制备高硅熔覆层,研究了激光扫描速度对熔覆层宏观形貌、相组成、显微组织、成分及硬度分布等的影响.结果表明,不同扫描速度条件下熔覆层表面均由-αFe(Si),-γFe(Si)和FeSi2组成;随扫描速度增大,熔覆层的组织有细化的趋势,组织不均匀性得到改善;同时,熔覆层厚度减小,导致稀释率减小,使熔覆层平均硅含量提高,显微硬度提高.通过调整激光扫描速度,获得了无裂纹缺陷,且与基体呈良好冶金结合的熔覆层,最佳扫描速度为2.5 mm/s.

High-Si coating was deposited on low-silicon steel substrate using laser to clad Fe-Si mixed powder onto that. The effects of laser scanning speed on the macro-morphology, phase composition, microstructure, chemical composition and microhardness of the laser cladding were investigated. The result showed that the cladding consists of α-Fe（Si）, γ-Fe （Si） and FeSi2 phases at different scanning speeds. The microstructure of the cladding tends to grain refinement with its inhomogeneity improved with increasing scanning speed and, meanwhile, average microhardness increases due to decreasing dilution ratio in the cladding as arising from its decreasing thickness. As a result, a pore and crack-free cladding with metallurgical bonding to the substrate is formed on low-silicon steel surface by adjusting the laser scanning speed of which the optimal one is 2.5 mm/s.