激光扫描速度对镍基合金熔覆层显微结构和耐腐蚀性能的影响

Effect of Laser Scanning Speed on Microstructure and Corrosion Resistance of Ni-based Alloy Coatings

摘要:

采用激光熔覆技术在Q235钢表面制备了镍基合金（含质量分数24%Cr、13%Mo）熔覆层，研究了激光扫描速度（100、200和300 mm/s）对熔覆层显微结构和耐腐蚀性能的影响，分析了熔覆层的显微组织、相组成、元素稀释率、显微硬度和耐腐蚀性能。结果表明，熔覆层由γ-Ni(C, Mo, Fe)和Cr0.19Fe0.7Ni0.11固溶体组成。随着激光扫描速度的提高，熔覆层晶粒细化，元素稀释率降低，显微硬度提高。由于元素稀释率较高，在扫描速度100 mm/s制备的熔覆层在3.5%（质量分数）NaCl溶液中浸泡2 h后的腐蚀电位最低。但由于熔覆层质量好，表面钝化膜稳定，在3.5% NaCl溶液中浸泡7 d后，其耐腐蚀性能仍优于其他2种涂层。

Abstract:

Ni-based alloy (24wt% Cr, 13wt% Mo, and balanced Ni) coatings were prepared by laser cladding technique on Q235 steel. The effects of laser scanning speed (100, 200, and 300 mm/s) on microstructure and corrosion resistance of coatings were investigated. The microstructures, phase composition, element dilution rate, microhardness, and corrosion resistance of the coatings were analyzed. Results show that coatings consist of γ-Ni(Cr, Mo, Fe) and Cr0.19Fe0.7Ni0.11 solid solution. The grain size is refined, the element dilution rate is decreased, and the microhardness is enhanced with increasing the laser scanning speed. The coating prepared at scanning speed of 100 mm/s exhibits the lowest corrosion potential after immersion in 3.5wt% NaCl solution for 2 h due to its high element dilution rate. Whereas this coating shows better corrosion resistance than the other two coatings do after immersion in 3.5wt% NaCl solution for 7 d due to the good coating quality and stable passive film.