Full Length Research Paper
This article describes an innovative application of hardfacing using Gas Tungsten Arc Welding (GTAW) process with alloys in powder form incorporated directly into the weld puddle. Stellite 6 alloy was used on the substrate of SAE 1020 steel mainly due to wear resistance. The good wear resistance is due to the characteristics of Co-Cr carbide dispersed in a matrix alloy deposited. Vickers hardness data, deposition rate, dilution, optical micrograph and Scanning Electron Microscopy (SEM) with the corresponding EDS spectra analysis were performed and compared with the results of the processed PTA. The results showed pore-free coating without surface oxidation and dilution higher than the PTA process. Microstructural analysis showed a finer microstructure for the PTA process, possibly due to the low dilution rate. But it was found that for the semi-automatic GTAW process, there also appeared dendritic microstructure little finer than the proximity permitted good properties of both processes, PTA automatic and semi-automatic GTAW. The hardness obtained through PTA and semi-automatic GTAW were similar throughout the deposited material, as areas rich in Co-Cr carbides in the matrix were intense. Therefore, the wear resistance and the PTA processes GTAW automatic, were approximately 19.2% higher for 9 g/min deposition rate and 8.9% in deposition rate of 19 g/min, for the highest dilution with automatic GTAW.
Key words: Gas Tungsten Arc Welding (GTAW), PTA, hardfacing, wear resistance.
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