INFLUENCE OF LIQUID NITROGEN COOLING ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF FRICTION STIR WELDED(FSW) DISSIMILAR AA5083 AA6061 ALUMINUM ALLOY JOINTS
In this paper, the effect of cryogenic (liquid nitrogen) cooling on grain size and influence of microstructure on mechanical properties of Friction stir welded (FSW) dissimilar Aluminium 5083 and 6061 alloys were studied due to their range of usage in naval and marine applications. However cryogenic (liquid nitrogen) coolant was employed immediately behind the FSW tool for rapid cooling to reduce the grain size and improve the mechanical properties of AA5083 and AA6061 Aluminum alloy. The welding parameters such as, welding speed, tool rotational speed and tool pin profile plays a major role in deciding the weld quality. The square tool profile generates a fairly localized deformation which results high volume of material was stirred and carried with the pin tool and also better mixing of plasticized metal. It was observed that better mechanical properties are obtained at rotational speed of 900rpm and welding speed of 31.5mm/min the fine microstructure is obtained. It was also observed that mechanical properties are enormously enriched. The experimental grain size and mechanical properties have correlated by microstructures and fracture structures.