Strain hardening effect in austenite ferrite dual-phase steel subjected to tensile deformation

Abstract

Duplex stainless steel (DSS) with an austenite-ferrite duplex microstructure offers high strength and toughness, excellent resistance to intergranular and chloride corrosion, and good weldability. The strain hardening behavior of austenite and ferrite phases in duplex stainless steel, when subjected to a tensile stress condition, is studied in the current work. Specimens were prepared from test blocks soaked at a temperature of 1160˚ C followed by furnace cooling to 1060 ˚C and water quenching. Heat-treated samples were deformed for varied percentage elongations. Microstructural analysis using optical microscopy revealed the deformations in austenite and ferrite phases. The concentrations of component alloying elements were determined using Energy Dispersive X-Ray Analysis (EDX) and area-scan techniques. At each level of percentage deformations, as well as on the fractured sample, microhardness measurements were taken on both austenite and ferrite phases. The hardness values of both austenite and ferrite phases were observed to rise continuously with an increase in deformation. The rise in hardness value of the ferrite phase was found to be significantly higher than the rise of hardness in the austenite phase, proving that the ferrite phase has a higher work hardening with deformation.