ZL101铝合金低周疲劳行为研究

研究了ZL101-T6铝合金的拉压低周疲劳行为,并重点分析了疲劳裂纹在材料中萌生与扩展的过程。通过扫描电镜和金相显微镜的观察分析表明:共晶硅相的断裂是材料低周疲劳裂纹萌生的主要方式,硅颗粒断裂的数量随疲劳循环周次的增加而增加,应变幅值的增加加快了硅颗粒的断裂速率,使疲劳裂纹的萌生速率加快;疲劳裂纹在循环初期主要通过断裂硅颗粒的互相连接进行扩展,随疲劳裂纹的长大,裂纹可穿过铝基体连接形成主裂纹并导致材料破坏,穿晶断裂为最终断裂的主要特征。

Low Cycle Fatigue Behavior of ZL101 Aluminum Alloy

The low cycle fatigue behavior of ZL101-T6 aluminum alloy has been investigated , focusing on the crack initiation and propagation in the alloy, by scanning electronic microscope (SEM) and metallographic microscope. The results show that the crack of eutectic Si phase is mainly responsible for the low cycle fatigue crack initiation. The amount of crack Si particles is increased with increasing in fatigue cycles, and the crack rate of Si particle,which can be accelerated with the increase of strain amplitude,promotes the propagation rate of fatigue crack. The propagation of fatigue crack is mainly dependent on the connection of adjacent cracking eutectic Si particles during initial cycling stages. With the growth of micro-crack, transgranular coalescence can be taken place in Al matrix to form a long fatigue crack, resulting in the final rupture of the alloy. So the final rupture in the ZL101 aluminum alloy is characterized by the transgranular fracture.