Microstructure and mechanical properties of friction stir welded SAF 2507 super duplex stainless steel

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2005-04, Vol.397 (1), p.376-384
• Main Authors: Sato, Y.S., Nelson, T.W., Sterling, C.J., Steel, R.J., Pettersson, C.-O.
• Format: Article
• Language: English
• Subjects: Applied sciences; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Cross-disciplinary physics: materials science; rheology; Duplex stainless steel; Exact sciences and technology; Friction stir welding; Hardness; Joining, thermal cutting: metallurgical aspects; Materials science; Mechanical properties; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microstructure; Physics; Treatment of materials and its effects on microstructure and properties; Welding
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2005.02.054

The microstructure and mechanical properties of friction stir (FS) welded SAF 2507 super duplex stainless steel were examined. High-quality, full-penetration welds were successfully produced in the super duplex stainless steel by friction stir welding (FSW) using polycrystalline cubic boron nitride (PCBN) tool. The base material had a microstructure consisting of the ferrite matrix with austenite islands, but FSW refined grains of the ferrite and austenite phases in the stir zone through dynamic recrystallisation. Ferrite content was held between 50 and 60% throughout the weld. The smaller grain sizes of the ferrite and austenite phases caused increase in hardness and strength within the stir zone. Welded transverse tensile specimen failed near the border between the stir zone and TMAZ at the retreating side as the weld had roughly the same strengths as the base material.