Detwinning Phenomenon and Its Effect on Resulting Twinning Structure of an Austenitic Hadfield Steel

Hadfield Steel shows high strain hardening which can be linked to its ability to form twins during mechanical loading. Twinning in Hadfield Steel is well documented, however, detwinning in Hadfield Steel is only barely investigated. Detwinning provides an additional contribution to plastic deformation, therefore it might be an essential effect during cyclic loading. In order to gain more information regarding the deformation behavior in Hadfield Steel, the present work concentrates on the twinning and detwinning behavior during interrupted tensile tests. Tensile tests were conducted in situ within a scanning electron microscope and interrupted at predefined elongations. To determine the formation of twins during every interruption, the electropolished tensile test sample was analyzed by electron backscatter diffraction. The first twins appeared after 5 to 10 pct strain. Conversely, tensile test interruptions at 30 and 40 pct elongation showed partial detwinning of the twinned regions. Furthermore, the Kernel Average Misorientation of the twinned and detwinned regions was analyzed. High values of misorientation were found not only in the twinned but also in the detwinned regions, thus the high level of misorientation can be linked to the twinning/detwinning process.

Automated summary

Hadfield Steel demonstrates high strain hardening attributed to twin formation during mechanical loading. While twin formation in Hadfield Steel is well-documented, detwinning is poorly understood. Detwinning contributes to plastic deformation and may be crucial during cyclic loading. This study focuses on the twinning and detwinning behavior in Hadfield Steel through interrupted tensile tests conducted within a scanning electron microscope. Electron backscatter diffraction analysis reveals the appearance of the first twins after 5 to 10 pct strain, and partial detwinning at 30 and 40 pct elongation. Kernel Average Misorientation analysis indicates high misorientation in both twinned and detwinned regions, linking it to the twinning/detwinning process.