Studies on flow stress behaviour prediction of AZ31B alloy: Microstructural evolution and fracture mechanism

• Published in: Journal of materials research and technology 2023-11, Vol.27, p.5541-5558
• Main Authors: Jaimin, Aarjoo, Kotkunde, Nitin, Singh, Swadesh Kumar, Saxena, Kuldeep Kumar
• Format: Article
• Language: English
• Subjects: AZ31B alloy; Constitutive equation; Flow stress behaviour; Fracture mechanism; Microstructural evolution
• ISSN: 2238-7854
• DOI: 10.1016/j.jmrt.2023.10.206

The hot tensile flow behaviour of the AZ31B alloy is investigated at various varying deformation temperatures (200–350 °C) and strain rates (0.1s−1, 0.01s−1, and 0.001s−1). The deformation condition significantly influenced the mechanical properties and microstructural evolution. Observation from the tensile tests indicated a strong dependence of flow stress on deformation temperature and strain rates. At a constant strain rate, flow stress decreased as the temperature increased, while at a constant deformation temperature, flow stress decreased with decreasing strain rates. The strain rate sensitivity varies from 0.01 to 0.25, suggesting a diffusion-controlled dislocation climb mechanism. Dynamic recrystallization (DRX) initiation was observed at 250 °C and a strain rate of 0.001s−1, characterized by the formation of necklace-type grains with low pole intensity. Predominantly, the DRX softening mechanism, including continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX), was observed at 350 °C and 300 °C for a strain rate of 0.001s−1. Fracture morphology analysis of the tested samples indicated a micro-void coalescence mechanism. Equiaxed dimples were found at 350 °C and a strain rate of 0.001s−1, while oval-shaped dimples were observed at 300 °C and 0.1s−1. A strain-compensated Arrhenius model was incorporated to estimate the flow stress prediction for hardening and softening regions. Statistical parameters such as the average absolute relative error (AARE = 13.50) and coefficient of determination (R = 0.97) were calculated. Good agreement between experimental and prediction stresses was achieved at a 0.001s−1 strain rate for all deformation temperatures. •The flow stress of AZ31B alloy at different tensile temperatures (200, 250, 300, and 350 °C) and strain rates (0.1s−1, 0.01s−1, and 0.001s−1) was discussed.•The initiation of DRX at 250 °C refines the microstructure and reduces the basal pole intensity.•Grain boundary bulging (DDRX) was observed at 300°C-0.001s−1 deformation conditions.•The dominant fracture mechanism was micro-void coalescence. At 350 °C and 0.001 s−1 condition, equiaxed dimples were observed.•The strain-compensated Arrhenius model effectively predicted the flow stress under low strain rate conditions.