Effect of Deformation Temperature on the Portevin-Le Chatelier Effect in Medium-Mn Steel

Abstract

Experimental investigations of the plastic instability phenomenon in a hot-rolled medium manganese steel were performed. The effects of tensile deformation in a temperature range of 20⁻140°C on the microstructure, mechanical properties, and flow stress serrations were analyzed. The Portevin⁻Le Chatelier (PLC) phenomenon was observed for the specimens deformed at 60 °C, 100 °C, and 140 °C. It was found that the deformation temperature substantially affects the type and intensity of serrations. The type of serration was changed at different deformation temperatures. The phenomenon was not observed at room temperature. The plastic instability occurring for the steel deformed at 60 °C was detected for lower strain levels than for the specimens deformed at 100 °C and 140 °C. The increase of the deformation temperature to 100 °C and 140 °C results in shifting the PLC effect to a post uniform deformation range. The complex issues related to the interaction of work hardening, the transformation induced plasticity (TRIP) effect, and the PLC effect stimulated by the deformation temperature were addressed.

Keywords

• medium-Mn steel
• retained austenite
• Portevin–Le Chatelier phenomenon
• strain-induced martensitic transformation
• ultra-high strength steel