In situ investigation of extension twinning-detwinning and its effect on the mechanical behavior of AZ31B magnesium alloy. (15th October 2017)

• Record Type: Journal Article
• Authors: Wu, B.L.; Duan, G.S.; Du, X.H.; Song, L.H.; Zhang, Y.D.; Philippe, M.J.; Esling, C.
• Is Part Of: Materials & design. Volume 132(2017)
• Page Start: 57
• Page End: 65
• Publication Date: 2017-10-15
• Subjects: Magnesium alloy -- Twinning-detwinning -- Twin variant selection -- Local Schmid factor -- Strain accommodation factor; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2017.06.023
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: Magnesium alloys are usually dominated by the alternation of extension twinning and detwinning when subjected to cyclic plastic deformation. The twinning-detwinning process in AZ31B alloy was investigated by means of in situ observation under EBSD. It was shown that the activation of extension twinning is related to Schmid factor of a deformed grain, but twin variant selection is not directly linked to Schmid factor rank. Strain accommodation factor proposed on the concept of local Schmid factor (LSF) allows a good prediction for twin variant selection. A twin variant is favored when the strain accommodation factor is low. In addition, detwinning was found to induce Bauschinger effect in the alloy during compressive unloading. The completely detwinned twins are accommodated by the adjacent grains with very high strain accommodation factors. Extension twins can form and remain in both compression and tension processes of the cyclic deformation. Residual twins in the second cycle increase in number as compared with the first cycle. This was inferred to stimulate the cyclic strain hardening. Graphical abstract: Highlights: The twinning-detwinning process in AZ31B alloy was investigated. Twin variant selection is not directly linked to Schmid factor rank. Strain accommodation factor allows a good prediction for twin variant selection. Detwinning that induces Bauschinger effect is related to internal stress relaxation and accommodation factor.