Flame-Retardance, Mechanical Properties and Corrosion Resistance of Heat-Resistant Magnesium Alloy JIS MDC-AXS620 Die-Castings

Abstract

  The AXS620 alloy, a magnesium alloy specified by JIS H 5303, was evaluated. When a mixture of argon gas and SF₆ gas was used as cover gas, and the flow rate of argon gas was set to 20 L/min, the flow rate of SF₆ gas required to prevent AXS620 melts from igniting was 1/10 of that of AZ91D melts due to the good flame retardancy of AXS620. AZ91D chips with a diameter of 100 to 300 micrometers ignited 3 out of 10 times when heated for 10 seconds, while AXS620 chips with the same particle size did not ignite any of the 10 times. AXS620 die-casts exhibit good creep resistance and higher proof stress and ultimate tensile strength than AZ91D above 125 degrees. During salt spray test and combined cycle test, the corrosion loss of AXS620 plate die-casts was smaller than those of AZ91D and ADC12. These results indicate that the AXS620 alloy is a useful flame-retardant and heat-resistant alloy.