Two duplex stainless steels, Avesta 2205 from Avesta AB, Sweden, and Cromweld 3Cr12 from Cromweld Steels Ltd, UK, were welded by shielded metal arc using arc energies of between 0.4 to 1.7 kJ/mm. The effects of varying heat inputs on the properties of the HAZ (heat affected zone), e.g., the hardness, the impact toughness, the tensile strength, the microstructure and the corrosion rate, are documented.