Improvement of surface properties of AISI 8620 steel

In order to prevent losses in materials used in the manufacturing industry (especially due to wear and corrosion), steel types with new properties are developed or coating processes are carried out on existing steels. AISI 8620 steels, known as case hardening steels, are widely used in the construction of shafts, piston pins and gear wheels. Alloying elements such as chromium, molybdenum, tungsten and vanadium are added to the steel alloy to improve the corrosion, wear and mechanical properties of AISI 8620 steels. At the same time, the surface properties of existing steels are improved by using various coating methods (electrolytic, thermal spray, nitriding, boriding, physical vapor deposition, chemical vapor deposition). In this study, AISI 8620 steel was borided using the box boriding method after being electrochemically chrome plated. After the characterization of the coatings by optical and SEM-EDX microscopy, the phases formed on the surface were analyzed by the XRD method. The friction, wear and hardness behaviors of the examined samples were then determined by the Tafel method, and their corrosion properties were determined before and after coating. As a result, in boronized samples; It was determined that the boride layer thickness increased with increasing boriding temperature and duration. It was observed that the hardness value of boron-coated samples was higher compared to Cr-coated samples. It was determined that the wear rate and value of the Cr coated sample were lower than other samples. When the corrosion resistances were compared, it was seen that the Cr coated sample had higher corrosion resistance than the boron coated samples.