Crack initiation mechanism of extruded AZ31 magnesium alloy in the very high cycle fatigue regime
Crack initiation mechanism of extruded AZ31 magnesium alloy in the very high cycle fatigue regime
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DOI：
10.1016/j.msea.2008.02.003
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发表时间：
2008-09
期刊：
影响因子：
6.4
通讯作者：
Fan Yang;S. Yin;S. Li;Zhefeng Zhang
中科院分区：
文献类型：
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作者：
Fan Yang;S. Yin;S. Li;Zhefeng Zhang
对商用挤压AZ31镁合金进行了超声波疲劳试验和常规疲劳试验。该合金的 S-N 曲线在非常高的循环状态下似乎有连续下降的趋势。 109次循环时的疲劳强度为88.7±4.1MPa。十亿次循环的耐久性极限与拉伸强度的比率（σ−1/σb）为0.301。疲劳破坏主要源自试件表面或近表面，循环加载后出现变形孪晶。沿双带观察到疲劳裂纹。基于孪生引起的循环变形不可逆性，提出了表面/近表面裂纹萌生的疲劳损伤机制。
Ultrasonic fatigue testing as well as conventional fatigue testing has been conducted on commercial extruded AZ31 magnesium alloy. The S–N curve for this alloy appears to have a continuous decreasing trend in the very high cycle regime. Fatigue strength at 109cycles is 88.7±4.1MPa. The ratio of endurance limit at one billion cycles to the tensile strength (σ−1/σb) is 0.301. Fatigue failure mainly originated from the specimen surface or near surface, where deformation twins were found after cyclic loading. Fatigue cracks were observed along twin bands. Based on cyclic deformation irreversibility caused by twinning, fatigue damage mechanisms are proposed in terms of surface/near surface crack initiation.