Degradation of Impact Toughness due to Formation of R Phase in High Nitrogen 25Cr-7Ni-Mo Duplex Stainless Steels

摘要: Influences of the formation behavior R phase on hardness and impact toughness were experimentally studied for high nitrogen duplex stainless steels containing 25 mass% Cr, 7 mass % Ni, 3 to 5 Mo, 0.14 0.27 N, 0.02 C. The solution heat treated at 1 323 K 3.6 ks, then aged 873 various times between 1.0 1.08×10 4 ks. For steels, examined with a Vickers test Charpy test, respectively, whereas microstructure was observed by transmission electron microscopy as well optical microscopy. experimental results indicate that thin fine platelet precipitates are formed along {110} planes body-centered cubic (b.c.c) ferrite (α phase) early stages aging. causes brittle fracture thus significant degradation toughness.