The effect of using neem oil, gear Oil (85W90) as quenchants and stress relief heat treatment on mechanical properties of gas metal arc welded duplex stainless steel were studied and compared. The samples after welded were given post weld heat treatments which are stress-relief and quenching in lubricating and neem oil. The results of the studies show that quenching in neem and lubricating oils (85w90) improved some mechanical properties of the alloy after welding (i.e toughness and ductility). The research also shows that the stress relief heat treatment gives better strength compared to those that were quenched in lubricating oil (85W90) and neem oil but the reverse is the case in terms of toughness and ductility.