TWO-PHASE STAINLESS STEEL

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Disclosed is a two-phase stainless steel which has outstanding weldability during high heat input welding and excellent stress corrosion cracking resistance in a chloride environment containing corrosive gas. The two-phase stainless steel satisfies the relationship between formula (1) and formula (2) and has a chemical composition which comprises C : 0.03 mass% or less, Si : 0.2 mass% to 1 mass%, Mn : 5.0 mass% or less, P : 0.040 mass% or less, S : 0.010 mass% or less, sol. Al : 0.040 mass% or less, Ni : 4 mass% to 8 mass%, Cr : 20 mass% to 28 mass%, Mo : 0.5 mass% to 2.0 mass%, Cu : over 2.0 mass% but no more than 4.0 mass%, N : 0.1 mass% to 0.35 mass%, with the remainder being Fe and impurities. In addition, the two-phase stainless steel may contain one or more of V, Ca, Mg, B, and rare earth elements instead of some of the Fe. In formulae (1) and (2), each element symbol represents the content of each element in the steel (unit : mass%). (1) 2.2Cr + 7Mo + 3Cu > 66 (2) Cr + 11Mo + 10Ni < 12 (Cu + 30N)