An Investigation on the Hardness and Wear Rate of Surface Alloyed AISI304 Stainless Steel with Ti using GTA as Heat Source

Background: Stainless steels are mainly used where prevention of corrosion attack is the main criteria, but low surface hardness and high wear rate are key obstacles to extensive application. Methods: The surface alloying of AISI 304 stainless steel with titanium was carried out using the heat generated from the Gas Tungsten Arc (GTA). Experiments were conducted by varying the GTA parameters and the optimal parameter was determined. Composition of the surface alloyed layer was analysed using atomic emission spectrometer. The Ti alloyed surface layers were characterized using SEM imaging/EDAX analysis. Findings: Composition of the surface alloyed layer was analysed using atomic emission spectrometer and the results confirmed an increase in the Ti content on the surface layer when compared to the composition of the substrate. The EDAX analysis showed that intermetallic alloys are present in the Ti alloyed surface layers. The microhardness was measured using the Vickers microhardness testing machine and the hardness increased from 267.5 HV for the substrate to 2098 HV for the surface alloyed layer. The wear was measured using the pin-on-disk wear tester and the wear rate decreased from 14.78 x 10^-4 mm³/m for the substrate to 1.84 x 10^-4 mm³/m for the surface alloyed layer. The observation of the microstructure revealed that there is grain refinement in the Ti alloyed surface layer. Applications: The modified specimens can be used as medical implants, control rods in nuclear power plants, pump barrels petrochemical industry. This method can be used to improve the properties in specific area of a product.