Study on susceptibility of Al-Si alloy castings to surface refinement with TIG arc

Surface fusions were performed by GTAW (Gas Tungsten Arc Welding) surfacing process on plate castings of Al-7Si-Mg alloy with electric arc travel speeds from 200 to 800 mm/min in argon atmosphere. Their geometry and values of structural parameters were measured. Microhardness, frictional wear intensity and the fatigue strength of the alloy surface, refined through rapid solidification, have been investigated. Extensive calorimetric measurements of the net heat input for the gas tungsten arc welding process have been conducted. Arc and melting efficiencies were evaluated. A stepwise regression method was used to develop relationships between GTAW process parameters and energy transfer efficiency, as well as geometry, structure and hardness.