This study analyses the effect of welding on mechanical properties of ribbed bars of two cold-deformed austenitic stainless steels (new, low-nickel AISI 204Cu and traditional 304L types) and two duplex stainless steels (SAF 2205 type, cold and hot-worked). Welds have been carried out using shielded metal arc welding. The effect of welding on local mechanical properties has been studied using a universal hardness equipment, measuring universal and Vickers hardness, elastic and plastic energies and Young modulus. Measured values are correlated with the microstructure of base materials and heat-affected zone. Results show that heat during welding promotes recrystallisation of the microstructure, effect that depends on the degree of deformation. These phenomena can be easily studied with universal hardness. Results suggest that hot-worked 2205 duplex stainless steel can be welded in construction without meaningful modification of its properties. Cold-deformed grades will comply ductility requirements of Eurocode 2 after welding, although reductions of yield strength can be found in 2205 and 304.