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

Published

Author(s)

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

Abstract

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.
Citation
Materials Science and Engineering A
Volume
817

Keywords

Stress relaxation, magnesium, ductility improvement, grain boundary sliding

Citation

, 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], https://doi.org/10.1016/j.msea.2021.141349, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=930246 (Accessed October 20, 2021)
Created June 10, 2021, Updated May 14, 2021