Duplex 2304, also called Alloy 2304, is a molybdenum-free duplex stainless steel. It has a structure that is a balance of ferritic ad austenitic and is often used as a replacement for Alloys 304L and 316L.

Duplex 2304 is a 23% chromium, 4% nickel, molybdenum-free duplex stainless steel whose structure is a balance of ferritic and austenitic. It has general corrosion resistance similar or better than Alloys 304L and 316L but with yield strength nearly double that of austenitic stainless steels. Its duplex microstructure and low nickel and high chromium contents also allows Duplex 2304 to demonstrate improved stress corrosion resistant properties compared to 304 and 316.