Pulse TIG Welding of Two Al-Mg-Si Alloys

This article reports the influence of pulse tungsten inert gas (TIG) welding parameters on the microstructure, hardness and tensile strength of weld joints of two Al-(0.5-0.8%)Si-(0.5-0.6%)Mg alloy (T4) produced by using three pulse frequencies (25, 33, and 50 Hz) and two duty cycles (40 and 50%). It has been observed that the mechanical properties (hardness and tensile strength) are sensitive to microstructure of weld metal, which is appreciably affected by the pulse parameters. Low frequency produced higher strength and hardness than high pulse frequency under identical welding conditions. Weld metal and HAZ were found stronger than the base metal. SEM study showed that the fracture of weldment was mostly brittle type.