Development of a device adapted to perform the torch gas tungsten arc welding (GTAW) hardfacing using alloys in powder form

This work was aimed at developing a device adapted to any gas tungsten arc welding (GTAW) torch, allows obtaining hard coatings by depositing alloys in powder form. For the purpose of verifying the feasibility of implementing this process, the results and parameters were compared with the plasma transferred arc (PTA) process. Due to good wear resistance was used as the substrate alloy SAE 1020 and alloy STELLITE 6 powder as depositor/hardfacing. Deposition rate, ideal flow of protection, dilution, micrographic and X-ray diffraction analysis results were raised to evaluate the proposed technique. The data showed a coating by the process GTAW pore-free and lowest dilution for both the GTAW and PTA process semi-automatics. However, gas consumption was lower for the GTAW process (8 L/min), due to reduced flow of the carrier gas. Microstructural analysis showed a microstructure similar for both processes, but the process PTA presented a more refined microstructure, possibly due to the low dilution rate. We also conclude that the presence of phases identified as γ-Fe and γ-Ni led to an increase in dilution rate of the GTAW processes.   Key words: Gas tungsten arc welding (GTAW), plasma transferred arc (PTA), wear resistance, phase γ-Fe, phase γ-Ni.