The respiratory effects often seen in full time welders include bronchitis, Airway irrigation, lung function changes, lung fibrosis and a possible increase in the incidence of lung cancer. Functionally significant pulmonary fibrosis associated with exposure to silica dust, nitrogen dioxide gas and other components of the welding fume would appear to leads to severe form of fibrosis in welders. Traditionally, control of fumes and gases has been by enclosure and local exhaust ventilation, respiratory protective equipment may also be necessary in certain circumstances, in particular in confined spaces. In this context, an environmentally cleaner process has been invented at The Welding Institute (TWI), UK, which is popularly known as Friction Stir welding (FSW) process FSW is an environmentally cleaner process, due to the absence of a need for the various gases that normally accompany fusion welding. FSW process produces no smoke, fumes, arc glare and it is an eco friendly process. This paper deals with the improvement in micro hardness and mechanical properties shown by aluminum alloys after friction stir welding.