The main objective of the present work was to enhance the mechanical properties of AISI 1020 steel by depositing the TiB2-TiO2 composite coating on it with the help of the tungsten inert gas (TIG) cladding process. The semi-solid mixture of 50 wt.% of TiB2 and 50 wt.% of TiO2 was preplaced on AISI 1020 steel and a TIG torch was used as heat source to melt the preplaced layer as well as substrate layer to produce the new coating layer. Characteristics of the cladded layer were examined using Vickers microhardness tester, energy dispersive spectroscopy (EDS), scanning electron microscope (SEM) and X-ray diffractometer (XRD). The TIG currents have shown a significant influence on the microstructure and mechanical properties of the coated layer. Metallography result also shows that the input current of the TIG cladding has considerable effect on the microstructure and quality of the coating. Microstructural changes in the clad layer were studied in detail. The Vickers micro-hardness value of the coated layer increases with decrease in input current and maximum microhardness was achieved about 568 HV0.05 which was about 3.5 times higher than that of the substrate (157 HV0.05). The dry sliding abrasive wear test was performed against EN31 hardened alloy steel as counter body by pin-on-disc tribometer with sliding distance of 1036 meters. The coating produced at lower TIG current (110 A) exhibits minimum average wear rate 1.46 × 10-6 g/Nm while coating processed at higher TIG current (155 A) exhibits higher average wear rate 2.18 × 10-6 g/Nm. It was also concluded that the wear rate of the TiB2-TiO2 coating decreases with decreasing processing current and minimum wear rate (1.46 × 10-6 g/Nm) obtained up to 2.5 times lower as compare to wear of AISI 1020 mild steel substrate (3.65 × 10-6 g/Nm) which makes the TiB2-TiO2 coating suitable for application as wear resistance components. The average coefficient of friction also decreases with increasing TIG current and found maximum (0.76) and minimum (0.58) for the coating deposited at 110 A and 155 A current, respectively.

TiC – Fe composite coating was produced on AISI 1020 steel by the tungsten inert gas (TIG) cladding process to increase the hardness and wear resistance properties of the substrate. In this paper authors have investigated the effect of process parameters on the microstructure and hardness value of the coated layer. In this TIG cladding process the variable parameter is only current, whereas the other parameters such as scanning speed, standoff distance, and voltage and gas flow rate are fixed. Fe and TiC powders were mixed in the proper ratio of 80wt% - 20wt% and 90wt% - 10wt% respectively. The microstructure and micro-hardness value of the samples were investigated by the scanning electron microscope (SEM) and Vickers micro hardness tester. The result of SEM shows the distribution of the coating powder in the cladded zone. Micro hardness profile shows the variation of the hardness value in the cladded zone as well as in the substrate. The hardness value decreases with increase in distance from top surface of the cladded layer, which is due to difference in cooling rate. Also, the hardness value of cladded layer decreases with increase in current from 140A to 150A. The maximum hardness value of cladded layer was achieved as 262 HV0.05 with 140A current and composition of 90 wt.% - 10wt% (Fe - TiC), which was nearly two times higher than that of the as received AISI 1020 steel substrate. Keywords TIG, Microstructure, Micro hardness, Titanium Carbide (TiC), Iron (Fe) powder.

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In the present study, various compositions of TiB2-Co coating were deposited on AISI 1020 mild steel by tungsten inert gas cladding method. In this work, various heat energy of TIG with a fixed travelling speed of 1.5 mm/sec was used to deposit the coating layer. The aim of this study was to investigate the optimal heat input of TIG to develop a thick layer in terms of coating microstructure and bonding quality. The influence of cobalt addition and current variation on microhardness and wear properties of the cladded layer was also investigated. The metallographic examination and microstructural analysis were investigated by X-ray diffraction, scanning electron microscope (SEM) and energy dispersive spectroscopy. The microhardness and wear rate have been analyzed by Vickers microhardness and dry sliding wear test, respectively. The investigations reveal that the influence of heat input on the wear resistance and hardness of the coated layer was significant. The microhardness value increases with increase in wt.% of TiB2 coating powder when TIG parameter is constant. The microhardness value also increases with decrease in heat input of the TIG when composition of the coating is kept constant. The maximum microhardness value was achieved up to 2563 HV0.1 which was 15 times higher than the substrate hardness value of 170 HV0.1. From the wear test result, it was noticed that the minimum wear rate found was 8.24 × 10-8 g/Nm for the coating composed by lower heat input (720 J/mm) and higher wt.% of TiB2 (90 wt.%).

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