Abstract
Duplex stainless steels are very promising materials for chemical and petro-chemical industry due to their moderate strength, good toughness and excellent corrosion resistance. Investigation of welds made of duplex stainless steels using shielded arc welding with tubular wire, tungsten inert gas welding, electron and laser beam welding with different welding speeds and welding currents. Hardness was measured across the welds. Increase of hardness in autogen welds is explained by excess of ferrite as well as by carbide and nitride dispersion hardening.Weld metal crystallizes epitaxially on ferrite of underbead zone. The microstructure is discussed in terms of quasi-binary duplex stainless steel diagram and practical implications on welding.

Key words
Duplex Stainless Steel, weldability, microstructure, hardness

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