Size Effect on Magnesium Alloy Castings

作者：Li, Zhenming; Wang, Qigui; Luo, Alan A.; Zhang, Peng; Peng, Liming^*

来源：Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science, 2016, 47A(6): 2686-2704.

DOI：10.1007/s11661-016-3436-4

• HIGH-CYCLE FATIGUE
• MG-3ND-0.2ZN-0.4ZR WT.PERCENT ALLOY
• ATOMIC-FORCE MICROSCOPY
• Y-ZR ALLOY
• HEAT-TREATMENT
• FRACTURE MORPHOLOGY
• CORROSION BEHAVIOR
• CRACK INITIATION
• STAINLESS-STEEL
• ALUMINUM-ALLOYS

The effect of grain size on tensile and fatigue properties has been investigated in cast Mg alloys of Mg-2.98Nd-0.19Zn (1530 mu m) and Mg-2.99Nd-0.2Zn-0.51Zr (41 mu m). The difference between RB and push-pull fatigue testing was also evaluated in both alloys. The NZ30K(05)-T6 alloy shows much better tensile strengths (increased by 246 pct in YS and 159 pct in UTS) and fatigue strength (improved by 80 pct) in comparison with NZ30-T6 alloy. RB fatigue testing results in higher fatigue strength compared with push-pull fatigue testing, mainly due to the stress/strain gradient in the RB specimen cross section. The material with coarse grains could be hardened more in the cyclic loading condition than in the monotonic loading condition, corresponding to the lower sigma (f) and the higher sigma (f)/sigma (b) or sigma (f)/sigma (0.2) ratio compared to the materials with fine grains. The fatigue crack initiation sites and failure mechanism are mainly determined by the applied stress/strain amplitude. In LCF, fatigue failure mainly originates from the PSBs within the surface or subsurface grains of the samples. In HCF, cyclic deformation and damage irreversibly caused by environment-assisted cyclic slip is the crucial factor to influence the fatigue crack. The Coffin-Manson law and Basquin equation, and the developed MSF models and fatigue strength models can be used to predict fatigue lives and fatigue strengths of cast magnesium alloys.

• 出版日期2016-6
• 单位上海交通大学