| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive Ni-reduced duplex stainless steel material which has corrosion resistance and is excellent in shock toughness. SOLUTION: The alloy-saving duplex stainless steel material contains C of 0.06 mass% or less, Si of 0.1 to 1.5 mass%, Mn of 0.1 to 6.0 mass%, P of 0.05 mass% or less, S of 0.005 mass% or less, Ni of 0.25 to 4.0 mass%, Cr of 19.0 to 24.0 mass%, Mo of 1.0 mass% or less, Cu of 3.0 mass% or less, N of 0.15 to 0.25 mass%, Al of 0.003 to 0.050 mass% and O of 0.007 mass%, and has an austenite phase fraction of 30 to 70 mass%, wherein, when a surface parallel to the surface of steel material is turned to a microscopic observation surface, electrolytic etching is performed for 90 s with electric current density of 0.1 A/cm<SP>2</SP>in 10% oxalic acid and microscopic observation is performed in an observation viewing field of at least 1 mm<SP>2</SP>, the total length of parts where crystal grain boundaries become grooves gets to be 1.5 mm or less per 1 mm<SP>2</SP>of observation viewing field. COPYRIGHT: (C)2011,JPO&INPIT |
