送粉式激光增材制造TC4钛合金熔覆层组织及电化学腐蚀行为的研究

Microstructure and Electrochemical Corrosion Behavior of TC4 Titanium Alloy Cladding Layer Prepared with Powder Feeding Laser Additive Manufacturing

采用激光增材制造(LDM)技术在TC4钛合金基体表面制备了TC4钛合金熔覆层,研究了不同扫描速率下制备的熔覆层的组织、显微硬度以及其在H_2SO_4溶液中的抗电化学腐蚀性能。结果表明:熔覆层的主要物相为α-Ti,且在β晶界附近生成了细针状α′马氏体,组织呈正交状网篮结构;随着扫描速率增大,熔覆层的平均显微硬度先增大后减小,腐蚀电流密度先降低后升高,电荷转移电阻先增大后减小,即其耐蚀性先增强后减弱;当扫描速率为10 mm/s时,熔覆层具有最大的平均显微硬度(390 HV)、最小的腐蚀电流密度(1.2337μA·cm^(-2))、最大的电荷转移电阻(11500Ω·cm^(-2)),此时的熔覆层具有较好的抗电化学腐蚀性能。

TC4 alloy cladding layer is prepared on TC4 titanium alloy substrate with laser additive manufacturing(LDM)technology,and the microstructure,microhardness and electrochemical corrosion resistance of the cladding layers in sulfuric acid solution are studied.The results show that the main phase of the cladding layers isα-Ti,and the fine acicularα′martensite is formed near theβgrain boundary,showing orthogonal basket-weave microstructure.With the increase of the scanning speed,the average microhardness of the cladding layers increases first and then decreases,the corrosion current density decreases first and then increases,and the charge transfer resistance increases first and then decreases,that is,its corrosion resistance also strengthens first and then weakens.In contrast,when the scanning speed is 10 mm/s,the cladding layer has the highest average microhardness(390 HV),minimum corrosion current density(1.2337μA·cm^-2),and maximum charge transfer resistance(11500Ω·cm^-2),and at this time,the cladding layer has better resistance to electrochemical corrosion.