Temperature dependence of mode I fracture behaviour of a textured magnesium alloy

Sreedhar, SA and Baruah, D and Shankar, G and Suwas, S and Narasimhan, R (2022) Temperature dependence of mode I fracture behaviour of a textured magnesium alloy. In: International Journal of Fracture, 238 (2). pp. 89-114.

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Abstract

Mode I, static fracture experiments and uniaxial tension/compression tests are conducted at three temperatures in the range from 25 to 100∘C using fatigue pre-cracked four-point bend and micro-tensile/compression specimens machined from a rolled AZ31 Mg alloy plate. Digital image correlation technique along with in-situ optical imaging is employed to analyse the specimen surface deformation. It is found that the fracture mechanism which is operative near the tip changes from quasi-brittle cracking caused by tensile twins to ductile void growth and coalescence as temperature is raised above 65∘C. This corroborates with reduction in tensile twin development near the crack tip with enhancement in temperature. On the other hand, at higher temperature, more profuse twinning and pronounced texture changes are perceived in the far-edge of the ligament, where compressive normal stress prevails. Simplified analyses are performed to show that the evolution rate of tensile twin volume fraction with energy release rate J near the tip will diminish strongly, while micro-void growth rate will enhance between 25 and 100∘C, thereby triggering the observed brittle-ductile transition. The fracture toughness rises dramatically above 65∘C and is also accompanied by significant notch blunting. This is rationalized from the transition in fracture mechanism and large plastic dissipation in the ligament far-edge due to twinning.

Item Type:	Journal Article
Publication:	International Journal of Fracture
Publisher:	Springer Science and Business Media B.V.
Additional Information:	The copyright for this article belongs to Springer Science and Business Media B.V.
Keywords:	Crack tips; Fracture mechanics; Growth rate; Magnesium alloys; Optical correlation; Temperature distribution; Textures, Basal textures; Fracture behavior; Fracture experiments; Fracture mechanisms; Mg alloy; Mode I fracture; Static fractures; Temperature dependence; Tensile twinning; Uni-axial tension-compression test, Fracture toughness
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	29 Dec 2022 11:24
Last Modified:	29 Dec 2022 11:24
URI:	https://eprints.iisc.ac.in/id/eprint/78623

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