Study on Surface Treatment and Corrosion Resistance of Crankshaft Mold

Ti/CrN and Ti/TiN/Cr coatings were prepared on the surface of 4Cr5MoVSi1 hot work die steel by multi-arc ion plating. The phase composition, microscopic morphology, and corrosion resistance of the two coatings were compared and analyzed. The results show that Ti/CrN coating is mainly composed of Ti and CrN phases, while Ti/TiN/Cr coating is mainly composed of Ti, TiN, and CrN phases. The surface morphologies of the two coatings are similar, with bright white particles and a small number of micro pits. The average microhardness of Ti/CrN and Ti/TiN/Cr coatings are 27.74 and 30.72 GPa, respectively, which are 5.44 and 6.02 times that of the substrate. With the increase of the corrosion time, the aluminum corrosion depth of the crankshaft mold matrix gradually increases,reaching 0.18 mm at 120 min. Both coatings show good resistance to high-temperature aluminum corrosion within120 min; no obvious corrosion is found on the surface of the coating, and no defects such as bulging or interface cracks in the coating.