Activated TIG welding has been performed on Al – 8% SiC composite 5mm plate with various fluxes such as Al₂O₃, MnO₂, CaO, MgO, SiO₂ & TiO₂. Microstructure, Micro hardness and cooling rate are observed. Correlation between micro hardness, microstructure and cooling rate of Constant Current TIG welding and Activated TIG welding on Al-SiC composite has been studied.  ATIG welding on Al-SiC composite showed fine superior weld microstructure on ATIG – SiO₂ & ATIG – TiO₂, this resulted in higher micro hardness. Micro hardness are observed in different locations of weld surface such as 1mm, 2mm & 3mm below the weld surface and it also observed along the weld zone to heat affected zone upto 12mm for the profiling the micro hardness value around the weldment.  Microstructure observed in weld centre for observed on the weld zone. 3mm away from the weld centre line shows interaction of weld zone & heat affected zone. 7mm away from the weld centre line shows the heat affected zone. Minimum micro hardness value of found in ATIG – MnO₂, ATIG – CaO & ATIG – MgO due to intermediate micro structure between coarse and fine in heat affected zone. ATIG – Al₂O₃ weld zone & heat affected zone and heat affected zone of ATIG – MnO₂, ATIG – CaO & ATIG – MgO shows coarse microstructure. This resulted in reduced micro hardness.  Cooling rate for the different CCTIG & ATIG welding are recorded and correlation between the micro structures are studied. Coarse micro structure in weld zone and heat affected zone have least cooling rate. Fine micro structure in weld zone should have higher cooling rate. Heat affected zone directly depends on temperature gradient between the weld centre and weldment heat affected zone.