Cooling, Microstructure and Properties of Permanent Steel Mold Cast Wrought AZ80 Alloy with Varying Casting Wall Sizes

Abstract:

The wrought magnesium alloy AZ80, comprising 8 wt% aluminum, underwent fabrication via permanent steel mold casting (PSMC), involving three distinct stages with wall sizes measuring 6 mm, 10 mm, and 20 mm. The numerical simulation of the solidification showed that the cooling rate of the step casting increased, when the wall size decreased. The as-cast alloy's microstructure underwent scrutiny through optical microscopy and scanning electron microscopy (SEM), complemented by energy dispersive spectroscopy (EDS) analysis. Findings from the microstructure examinations unveiled the presence of primary Mg phase across all three sections of the cast AZ80 alloy, accompanied by micron and nanosized Mg-Al-Zn intermetallic phases, as well as micron-sized Al-Mn intermetallic phases. But the intermetallic contents increased, and the dendrite sizes and the porosity levels decreased, as the wall sizes reduced. The tensile testing results revealed significant findings regarding the ultimate tensile strength (UTS), yield strength (YS), modulus, resilience, and toughness, increased, when the wall sizes decreased to 6 from 20 mm. The negative effect of large casting wall sizes on ductility was demonstrated. Exceptional tensile properties of the thin wall resulted from fine dendritic structure, high intermetallic content, and minimal porosity level.

• Periodical: Materials Science Forum (Volume 1136)
• Pages: 81-89
• DOI: https://doi.org/10.4028/p-6MKFSi
• Online since: December 2024
• Authors: Lance Ying, Wu Tian Shen, Anita Hu, Henry Hu*
• Keywords: Casting Wall Size, Cooling, Microstructure, Numerical Simulation, Permanent Steel Mold Casting, Properties, Wrought Mg Alloy AZ80

References

[1] G. G. Wang, J. P. Weiler. Recent developments in high-pressure die-cast magnesium alloys for automotive and future applications, J Magnes Alloy. 11(1) (2023) 78-87.

DOI: 10.1016/j.jma.2022.10.001

[2] J. P. Weiler. Exploring the concept of castability in magnesium die-casting alloys, J. Magnes Alloy. 9(1) (2021)102-111.

DOI: 10.1016/j.jma.2020.05.008

[3] J. P. Weiler. A review of Mg die-castings for closure applications, J. Magnes. Alloy. 7 (2019) 297–304.

[4] A. A. Luo. Mg casting technology for structural applications, J Magnes Alloy. 1 (2013) 2–22.

[5] Y. Fu, Y. Li, A. Hu, H. Hu, X. Nie. Microstructure, Tensile properties and fracture behavior of squeeze-cast Mg alloy AZ91 with thick cross section, J. Materi. Eng. Perform. 29 (2020) 4130–4141.

DOI: 10.1007/s11665-020-04910-x

[6] Z. Sun, L. Ren, X. Geng, L. Fang, X. Wei, H. Hu. Influence of wall stocks on mechanical properties of HPDC AZ91, Key Eng. Mater. 793 (2019) 41–45.

DOI: 10.4028/www.scientific.net/kem.793.41

[7] Z. Sun, X. Geng, L. Ren, H. Hu. Microstructure, tensile properties and fracture behavior of HPDC magnesium alloy AZ91, International Journal of Materials, Mechanics and Manufacturing. 8(2) (2020) 50-56.

DOI: 10.18178/ijmmm.2020.8.2.483

[8] G. Gu, S. Lin, Y. Xia, Q. Zhou. Experimental study on influence of section thickness on mechanical behavior of die-cast AM60 magnesium alloy, Materials & Design. 38 (2012) 124-132.

DOI: 10.1016/j.matdes.2012.02.015

[9] X. Zhang, M. Wang, Z. Sun, H. Hu. Section thickness-dependent tensile properties of squeeze cast magnesium alloy AM60, China Foundry. 9(2) (2012) 178-183.

DOI: 10.1002/9781118359228.ch101

[10] Avedesian, MM and Baker, H (ed) (1999). Magnesium and Magnesium Alloys, ASM International, Metals Park, OH.

[11] S. Kotiadis, A. Zimmer, A. Elsayed, E. Vandersluis, C. Ravindran. High electrical and thermal conductivity Cast Al-Fe-Mg-Si Alloys with Ni Additions, Metall. Mater. Trans. A. 51 (2020) 4195–4214.

DOI: 10.1007/s11661-020-05826-w

[12] Y. H. Zhang, Y. C. Liu, Y. J. Han, C. Wei, Z. M. Gao. The role of cooling rate in the microstructure of Al-Fe-Si alloy with high Fe and Si contents, J. Alloy. Compd. 473 (2009) 442–445.

DOI: 10.1016/j.jallcom.2008.06.004