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Grain boundary sliding and non-constancy strain during stress relaxation of pure Mg



Dilip K. Banerjee, Anand Varma, Aditya Gokhale, Jayant Jain, Krishnaswamy Hariharan


Stress relaxation during plastic deformation has been reported to improve ductility of metallic materials. In this study, the stress relaxation behavior in pure magnesium is investigated during interrupted uniaxial tensile tests. During intermittent stopping of the machine for relaxation studies, the total strain is expected to remain constant. However, an anomalous non-constancy in total strain is observed in the present work. The total strain increases with relaxation time. Additional in-situ tensile tests indicate that the non- constant total strain is restricted only in the gauge area of the specimen, indicating a likely shear dominated deformation such as grain boundary sliding (GBS) responsible for the anomalous behavior. The role of GBS during relaxation is studied using the deformation induced evolution of surface inhomogeneity. Determinations of surface profiling step heights at grain boundaries and inclination of grains were used to quantify the effect of GBS. The estimated activation volume of 4.35 b^3 further confirms the role of slip induced GBS on the deformation. A new stress relaxation model accommodating GBS is proposed and is found to fit the experimental data accurately.
Materials Science and Engineering A


Stress relaxation, magnesium, ductility improvement, grain boundary sliding


, D. , Varma, A. , Gokhale, A. , Jain, J. and Hariharan, K. (2021), Grain boundary sliding and non-constancy strain during stress relaxation of pure Mg, Materials Science and Engineering A, [online],, (Accessed May 28, 2024)


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Created June 10, 2021, Updated May 14, 2021