Effects of strain rate and humidity on tensile properties of AZ31 and AZ61 magnesium alloys

Tensile tests at various strain rates in humid air (HA) and dry nitrogen gas (DNG) were carried out to investigate the effects of strain rate and humidity on tensile properties of AZ31 and AZ61 magnesium alloys. In both alloys, the elongation in DNG increased with decreasing the strain rate. When the AZ31 alloy was tested at a strain rate of 1.39 ×10‒6s‒1 in HA, it showed a loss of elongation due to quasi-cleavage fracture. The degradation of ductility was observed in the AZ61 alloy as well as the AZ31 alloy. The embrittlement sensitivity was larger in the AZ61 alloy compared to the AZ31 alloy. In HA, hydrogen atoms arisen from chemical reaction between magnesium surface and water vapor were presumed to be absorbed into the specimen and result in hydrogen embrittlement.