Surface modification of AISI 8620 steel by in-situ grown TiC particle using TIG arcing

In-situ grown titanium carbide (TiC) reinforced steel matrix was produced with tungsten inert gas (TIG) arcing by the metallurgical reaction between titanium and graphite powder on bearing steel (AISI 8620). Microstructure, chemical composition, and formation of TiC precipitate particles were thoroughly analysed primarily for basic understanding of transformation characteristics and morphology of the TiC particles as a function of the process parameters. The microstructure was analysed with the help of several tools like field emission scanning electron microscope (FESEM) equipped with energy dispersive spectroscopy (EDS), electron probe micro analyzer (EPMA), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The treated surface was practically free from cracks and porosity. The modified surface consists of in-situ synthesized titanium carbide precipitate in the martensite matrix. The XRD results confirmed the presence of titanium carbide precipitate. The changes in TIG arcing parameters have been found to vary the dilution of the modified zone which has subsequently affected the concentration of TiC precipitates in the modified region. Considerable enhancement in the mechanical properties of the modified surface was examined using microhardness and wear test. The average hardness of the modified surface with flux of lowest current reached to about 2.15 times that of the base metal. The wear test reveals the effectiveness of the TiC precipitate with the enhancement in wear resistance of about 4.6 times that of as received sample. Surface modification of the substrate was also carried out by employing TIG arcing without the addition of the flux coating to make a comparative study on the evolution of microstructure and its effect on mechanical behavior to find out the utility of using the flux coating for an exclusive benefit of the surface modification for superior properties.

Automated summary

In this study, in-situ grown titanium carbide reinforced steel matrix was produced using tungsten inert gas (TIG) arcing, with thorough analysis of the microstructure, chemical composition, and formation of TiC precipitate particles. By varying the TIG arcing parameters, the concentration of TiC precipitates in the modified region was found to be affected, resulting in significant enhancement in hardness and wear resistance of the modified surface. The presence of titanium carbide precipitates in the modified surface was confirmed through XRD analysis, showcasing the effectiveness of the surface modification process.