Low cycle fatigue behavior of T4-treated Al-Zn-Mg-Cu alloys prepared by squeeze casting and gravity die casting

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• 作者：Cheng-kun ZHENG ; Wei-wen ZHANG ; ^{mewzhang@scut.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Da-tong ZHANG ; Yuan-yuan LI
• 关键词：Al&ndash ; Zn&ndash ; Mg&ndash ; Cu alloy ; squeeze casting ; gravity die casting ; microstructure ; mechanical properties ; low cycle fatigue
• 刊名：Transactions of Nonferrous Metals Society of China
• 出版年：2015
• 出版时间：November 2015
• 年：2015
• 卷：25
• 期：11
• 页码：3505-3514
• 全文大小：11621 K

文摘

Gravity die casting (GC) and squeeze casting (SC) T4-treated Al–7.0Zn–2.5Mg–2.1Cu alloys were employed to investigate the microstructures, mechanical properties and low cycle fatigue (LCF) behavior. The results show that mechanical properties of SC specimens are significantly better than those of GC specimens due to less cast defects and smaller secondary dendrite arm spacing (SDAS). Excellent fatigue properties are obtained for the SC alloy compared with the GC alloy. GC and SC alloys both exhibit cyclic stabilization at low total strain amplitudes (less than 0.4%) and cyclic hardening at higher total strain amplitudes. The degree of cyclic hardening of SC samples is greater than that of GC samples. Fatigue cracks of GC samples dominantly initiate from shrinkage porosities and are easy to propagate along them, while the crack initiation sites for SC samples are slip bands, eutectic phases and inclusions at or near the free surface.