Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : September 03, 2023 - September 06, 2023
In this study, we aimed to increase the hot extrusion rate of AZX611 castings, a flame-retardant magnesium alloy with added calcium. Typically, the hot extrusion rate decreases because the deformation resistance increases owing to strengthening of the solid solution during hot extrusion upon the addition of aluminum and owing to enhanced dispersion of second-phase particles upon the addition of calcium for flame retardance. We performed a high-temperature tensile test to investigate the high-temperature mechanical properties as a preliminary step toward increasing the hot extrusion speed of AZX611 alloy castings. The test conditions included a temperature range of 623–773 K (in air) and initial strain rates of 1 × 10-3 to 1 × 10-1 s-1. The initial microstructure was a dendritic cell structure of approximately 30 μm, and secondphase particles were observed within coarse grains of several hundred micrometers. These second-phase particles were identified as Al–Mg, Al–Ca, and Al–Mn compounds via energy-dispersive X-ray spectroscopy. These particles had an average diameter and area fractions of approximately 3–4 μm and 6–7%, respectively. Furthermore, the dominant hightemperature deformation mechanism involved enhanced dispersion of the second-phase particles at 623 K and 673 K, and the dislocation creep by self-diffusion of pure Mg occurred at 723 K and 773 K. Hot ductility increased with increasing temperature up to 723 K and with decreasing initial strain rate.
