AZ31镁合金的缺口冲击韧性及其断裂机理

Notch Impact Toughness and Fracture Mechanism of AZ31 Magnesium Alloy

缺口冲击韧性是金属材料应用的一个重要动态性能指标。本文针对AZ31镁合金板材,在-80~260℃范围内,进行了Charpy V型缺口冲击试验,测试了其缺口冲击韧性随温度变化的规律,试验结果表明：在120~160℃范围内,AZ31镁合金存在韧脆转变现象,根据能量标准和延性标准测得的韧脆转变温度均为140℃。并通过SEM手段对-80℃、0℃、80℃、140℃、200℃以及260℃等典型温度下的冲击断口形貌进行了比较分析,结果表明在-80~80℃范围内断口为准解理形貌;80~200℃范围内断口形貌是准解理＋韧窝;200~260℃温度范围内断口是韧窝形貌。

Notch impact toughness is an important dynamic property for applications of metallic materials.Charpy V type notch impact test of AZ31 magnesium alloy was carried out from-80 ℃ to 260 ℃,and the relationship between notch impact toughness and temperature was tested.It is indicated that AZ31 magnesium alloy occurs ductile-brittle transition phenomena in the temperature range from 120 ℃ to 160 ℃,and the ductile-brittle transition temperature is about 140 ℃ according to both the energy criterion and ductility criterion.Moreover,scanning electron microscopy（SEM） micrographs of the fracture surfaces at-80 ℃,0 ℃,80 ℃,140 ℃,200 ℃ and 260 ℃ were comparatively analyzed,the results show that the fracture surfaces present quasi-cleavage patterns when temperature ranges from-80 ℃ to 80℃,quasi-cleavage and dimple patterns from 80 ℃ to 200 ℃ and many dimple patterns are found on fracture surfaces from 200 ℃ to 260℃.