Effect of Cryogenic Treatment on Ballistic Performance of Thick Magnesium Alloy (AZ31B) Plates
摘要
The effects of cryogenic treatment (CT) on the microstructure, microhardness, and ballistic performance of thick AZ31B magnesium alloy plates have been investigated. Three different cryogenic treatments such as, − 80 °C/10 h, − 196 °C/24 h, and − 196 °C/72 h were considered on the AZ31B plates of dimensions 155 mm × 78 mm × 12 mm thick before conducting the ballistic experiments. Conical nose-shaped projectile of diameter 7.62 mm and a velocity of 420 ± 20 m/s was considered for the ballistic experiments. Depth of penetration (DoP) was measured from the backing plate (AA6063) to determine the ballistic performance. The refinement of crystalline size (25.2 nm) and increase in the dislocation density was observed for the CT (− 196 °C/72 h). The α-Mg with non-uniform distribution of fine β-Mg17Al12 was observed along the grain boundaries of CT specimen. The microhardness of the CT specimen was 6.11% higher than the rolled specimen. The DoP of CT specimen was 22.10% lower than the rolled condition. Hence, CT (− 196 °C/24 h and − 196 °C/72 h) specimens exhibit higher ballistic resistances compared to the rolled condition. ‘Spalling failure mechanism’ was observed for the rolled specimens and whereas ‘ductile hole growth’ was observed for the CT specimens. The post-ballistic fracture surface of the rolled specimen showed cracks and voids along the penetration channel.