Investigation on the solution treated behavior of economical 19Cr duplex stainless steels by Mn addition

• Published in: Materials & design 2015-10, Vol.83, p.820-828
• Main Authors: Yang, Yinhui, Cao, Jianchun, Gu, Yang
• Format: Article
• Language: English
• Subjects: Austenite; Duplex stainless steels; Economics; Formations; Fracture mechanics; Fracture toughness; Manganese; Mn addition; Pitting corrosion; Solution treatment; Toughness
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2015.05.052

[Display omitted] •Solution treatment at 1220°C lowered toughness but higher Mn addition improved it.•Elongation fell greatly with Mn addition to 8.1wt.% even by solution treatment.•Decreasing trend of pitting corrosion potential got slower by 8.1wt.% Mn addition.•Higher pitting corrosion resistance was achieved by lowering solution temperature. Effect of Mn on microstructure, mechanical property and pitting corrosion of 19% Cr economical duplex stainless steels with solution temperatures ranging from 1040 to1220°C has been investigated. The austenite content increases with more Mn addition, but decreases by increasing solution temperature, which can be inferred by trend of partition coefficient KMn with solution temperature. Meanwhile, a balanced austenite-ferrite duplex structure of solution-treated specimens was obtained with Mn addition. The impact energy at 20°C increased with decreasing solution temperature from 1220°C to 1040 and 1120°C, and improved by more Mn addition due to more ductile austenite phase formation. These toughness variations were consistent with fracture morphology characteristic changing. The effect of more Mn addition and solution treatment of 1120°Con decreasing of tensile strength and 0.2% offset yield strength were slight. However, the elongation to fracture (%) fell greatly with Mn addition up to 8.1wt.% for as-rolled and solution treated specimens due to larger deformation strains of austenite than that of ferrite. The decreasing trend of pitting corrosion potential became slower with Mn addition from 3.6 to 8.1wt.%. The pitting corrosion resistance was lowered by increasing solution temperature due to more weakened repassivation ferrite phase formation.