| 摘要 |
PROBLEM TO BE SOLVED: To provide a two-phase stainless steel tube excellent in strength, corrosion property and low temperature toughness.SOLUTION: There is provided a two-phase stainless steel constituted by an austenite phase and a ferrite phase having a chemical component containing, by mass%, C:0.03% or less, Si:0.2 to 1%, Mn:0.5 to 2.0%, P:0.040% or less, S:0.010% or less, Sol.Al:0.040% or less, Ni:4% or more and less than 6%, Cr:20% or more and less than 25%, Mo:2.0 to 4.0%, N:0.1 to 0.35%, O:0.003% or less, V:0.05 to 1.5%, Ca:0.0005 to 0.02%, B:0.0005 to 0.02% and the balance Fe with impurities, a metallographic structure has no deposition of a sigma phase, a percentage of the ferrite phase in the metallographic structure is 50% or less and the number of oxides having a particle diameter of 30 μm or more existing in a 300 mmfield is 15 or less. |
