Stress distribution at different deformation degrees in low carbon steel during cold deformation

Abstract

The temperature change, i.e. stresses of low carbon steel during the cold deformation process was investigated in this study. During static tensile test, temperature changes were examined using thermography at different deformation degrees. It was found that there are temperature changes in the deformation zone during the cold deformation. The increase in temperature changes in the deformation zone during cold deformation occurs with an increase in the deformation degree. The largest localization of temperature change was measured at the moment of the test sample fracture when the maximum temperature change was 8.45 °C. A higher amount of temperature change of 5.39 °C was determined at tensile strength compared to the proportionality limit amount of -0.97 °C. It was found that there are differences between the amounts of temperature changes in the range from 0.87 °C to 1.91 °C with increasing of deformation degree of the tested steel. Calculated stress amounts proved and show the tendency that stress amounts increase as the temperature change increases in low carbon steel by increasing of deformation degree during cold deformation. It was determined deviations of the calculated stress amounts due to using the mathematical model for low carbon with niobium at the start of plastic flow.

Line Analysis of Changes in the Deformation Zone During Lüders Band Propagation

“…Lüders band, as one of the mentioned phenomena, is usually researched by applying thermography and digital image correlation (DIC) [10]. Under certain conditions, with these methods it can be determined distribution and values of temperature changes (associated with stress changes in deformed metal [10]) and deformation during the plastic flow both of steel and other metal materials [11,12]. Thermography and DIC results can be presented by line and point analysis, thus analysis of a certain zone of interest that shows appearance and propagation of the Lüders band, but also other phenomena happening during the plastic deformation of steel [13][14][15][16].…”