紧固件用耐蚀合金熔覆层的制备与性能研究

Preparation and Properties of Corrosion Resistant Alloy Cladding Layer for Fasteners

针对常用紧固件防腐工艺不能满足实际防腐需求的难题,本文提出了基于激光熔覆技术的紧固件防腐新思路并进行了实验验证。实验采用了10种激光熔覆参数,在镀铬和未镀铬45#钢棒材上制备了哈氏合金C22熔覆层。研究了熔覆层的微观形貌、稀释率、显微硬度及极化曲线。结果表明:熔覆层与基体结合良好,无明显裂纹。在基体表面镀铬后再进行激光熔覆,可有效降低熔覆层稀释率。熔覆层表面的显微硬度可达到320HV0.5,高于基体硬度200 HV0.5。熔覆层具有较高自腐蚀电位Ecorr=-0.335 V和较低自腐蚀电流密度Icorr=2.133×10-6 A/cm-2,可有效保护基体金属。激光熔覆技术应用于紧固件的防腐具有可行性。

Aiming at the problem that the common fastener anti-corrosion process cannot meet the actual anti-corrosion requirements, this paper proposes a new idea to improve fastener anti-corrosion based on laser cladding technology and the results have been verified by experiment. Ten laser cladding parameters were used to prepare the C22 cladding layer of Hastelloy alloy on chromium-plated and non-chromium-plated 45 steel bars to study the microscopic appearance, dilution rate, microhardness and polarization curve of the cladding layer.The results show that the cladding layer has a good bonding with the matrix, without obvious cracks. The dilution rate of the cladding layer can be effectively reduced by first plating chromium on the surface of the substrate and then laser cladding. The microhardness of the cladding layer’s surface can reach 320 HV0.5, 200 HV0.5 higher than that of the matrix. Since the cladding layer has a higher self-corrosion potential(Ecorr=-0.265 V) and a lower self-corrosion current density(Icorr=4.784×10-7 A/cm-2), the base metal can be efficiently protected. Therefore, a conclusion can be drawn that it is feasible to apply laser cladding technology to anti-corrosion of fasteners.