Effect of scanning speeds on electrochemical corrosion resistance of laser cladding TC4 alloy**Project supported by the National Natural Science Foundation of China (Grant Nos. 61475117 and 51471084), the National Key Research and Development Program of China (Grant No. 2017YFB1103604), and the Tianjin Municipal Special Program of Talents Development for Excellent Youth Scholars, China (Grant No. TJTZJHQNBJRC-2-15).

Abstract

In order to study the effect of scanning speed on the electrochemical corrosion resistance of laser cladding TC4 alloy in artificial seawater, the x-ray diffraction analysis, microstructure of cross-section, microhardness variation, and impedance spectrum have been studied in comparison with the TC4 titanium alloy. The results show that the main phase of cladding coating is α-Ti, and the change of scanning speed has no obvious effect on it; therefore, the supersaturated α-Ti solid solution is formed, and the acicular martensite is obtained. As the scanning speed increases, the microstructure of cladding coating is orthogonal basket-weave, the crystal surface spacing decreases, and the average microhardness of laser cladding TC4 alloy slightly increases. When the scanning speed increases to 10 mm/s, the microhardness is about 14.71% higher than that of the substrate, and the electrochemical corrosion resistance of laser cladding TC4 alloy is also improved, which is about 2.48 times more than the substrate. Grain refinement has a great effect on enhancing the anti-electrochemical corrosion.