Abstract
The characteristics of defect bands in the microstructure of high pressure die casting (HPDC) AE44 magnesium alloy were investigated. Special attention was paid to the effects of process parameters during the HPDC process and casting structure on the distribution of defect bands. Results show that the defect bands are solute segregation bands with the enrichment of Al, Ce and La elements, which are basically in the form of Al11RE3 phase. There is no obvious aggregation of porosities in the defect bands. The width of the inner defect band is 4–8 times larger than that of the outer one. The variation trends of the distribution of the inner and outer defect bands are not consistent under different process parameters and at different locations of castings. This is due to the discrepancy between the formation mechanisms of double defect bands. The filling and solidification behavior of the melt near the chilling layer is very complicated, which finally leads to a fluctuation of the width and location of the outer defect band. By affecting the content and aggregation degree of externally solidified crystals (ESCs) in the cross section of die castings, the process parameters and casting structure have a great influence on the distribution of the inner defect band.
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References
Gjestland H, Westengen H. Advancements in high pressure die casting of magnesium. Advanced Engineering Materials, 2007, 9: 769–776.
Zhao X, Wang P, Li T, et al. Gating system optimization of high pressure die casting thin-wall AlSi10MnMg longitudinal load-bearing beam based on numerical simulation. China Foundry, 2018, 15(6): 436–442.
Dong X X, Zhu X Z, Ji S X. Effect of super vacuum assisted high pressure die casting on the repeatability of mechanical properties of Al-Si-Mg-Mn die-cast alloys. Journal of Materials Processing Technology, 2019, 266: 105–113.
Wang C T, Yao J, Zhao H D, et al. Influence of intensification pressures on pores in die-cast ADC12 alloys. China Foundry, 2019, 16(3): 184–189.
Li X B, Xiong S M, Guo Z P. Correlation between porosity and fracture mechanism in high pressure die casting of AM60B alloy. Journal of Materials Science & Technology, 2016, 32(1): 54–61.
Kang H J, Yoon P H, Lee G H, et al. Evaluation of the gas porosity and mechanical properties of vacuum assisted porefree die-cast Al-Si-Cu alloy. Vacuum, 2021, 184: 109917.
Wu M W, Li X B, Guo Z P, et al. Effects of process parameters on morphology and distribution of externally solidified crystals in microstructure of magnesium alloy die castings. China Foundry, 2018, 15(2): 139–144.
Li X B, Xiong S M, Guo Z P. Characterization of the grain structures in vacuum-assist high-pressure die casting AM60B alloy. Acta Metallurgica Sinica (English Letters), 2016, 29(7): 619–628.
Li X B, Xiong S M, Guo Z P. Influence of melt flow on the formation of defect band in high pressure die casting of AZ91D magnesium alloy. Materials Characterization, 2017, 129: 344–352.
Bladh M, Wessén M, and Dahle A K. Shear band formation in shaped rheocast aluminium component at various plunger velocities. Transactions of Nonferrous Metals Society of China, 2010, 20: 1749–1755.
Meylan B, Terzi S, Gourlay C M, et al. Development of shear bands during deformation of partially solid alloys. Scripta Materialia, 2010, 63: 1185–1188.
Dahle A K, Sannes S, St. John D H, et al. Formation of defect bands in high pressure die cast magnesium alloys. Journal of Light Metals, 2001, 1(2): 99–103.
Huang X S, He L J, Mi G B, et al. Characteristics of defect bands and their formation mechanisms in A356 wheel fabricated by horizontal squeeze casting. Materials Science and Technology, 2015, 31: 400–408.
Wang Q L, Xiong S M. Vacuum assisted high-pressure die casting of AZ91D magnesium alloy at different slow shot speeds. Transactions of Nonferrous Metals Society of China, 2014, 24: 3051–3059.
Zhou Y Q, Guo Z P, Xiong S M. Effect of runner design on the externally solidified crystals in vacuum die-cast Mg-3.0Nd-0.3Zn-0.6Zr alloy. Journal of Materials Processing Technology, 2019, 267: 366–375.
Laukli H I, Gourlay C M, Dahle A K, et al. Effects of Si content on defect band formation in hypoeutectic Al-Si die castings. Materials Science and Engineering: A, 2005, 413–414: 92–97.
Otarawanna S, Gourlay C M, Laukli H I, et al. The thickness of defect bands in high-pressure die castings. Materials Characterization, 2009, 60: 1432–1441.
Cao H, Wessén M. Characteristics of microstructure and banded defects in die cast AM50 magnesium components. International Journal of Cast Metals Research, 2005, 18: 377–384.
Yu W B, Ma C S, Ma Y H, et al. Correlation of 3D defect-band morphologies and mechanical properties in high pressure die casting magnesium alloy. Journal of Materials Processing Technology, 2021, 288: 116853.
Wu G H, Wang C L, Sun M, et al. Recent developments and applications on high-performance cast magnesium rare-earth alloys. Journal of Magnesium and Alloys, 2021, 9: 1–20.
Dong T S, Zheng X D, Wang T, et al. Effect of Nd content on microstructure and mechanical properties of as-cast Mg-12Li-3Al alloy. China Foundry, 2017, 14(4): 279–285.
Song J F, She J, Chen D L, et al. Latest research advances on magnesium and magnesium alloys worldwide. Journal of Magnesium and Alloys, 2020, 8: 1–41.
Xiao W L, Easton M A, Zhu S M, et al. Casting defects and mechanical properties of high pressure die cast Mg-Zn-Al-RE alloys. Advanced Engineering Materials, 2012, 14(1–2): 68–76.
Sharifi P, Jamali J, Sadayappan K, et al. Grain size distribution and interfacial heat transfer coefficient during solidification of magnesium alloys using high pressure die casting process. Journal of Materials Science & Technology, 2018, 34: 324–334.
Wang Q L, Xiong S M. Effect of multi-step slow shot speed on microstructure of vacuum die cast AZ91D magnesium alloy. Transactions of Nonferrous Metals Society of China, 2015, 25: 375–380.
Jiao F F, Zhang J H, He L L, et al. Al-RE intermetallic phase stability and effects on corrosion behavior in cold-chamber HPDC AE44 alloy. Advanced Engineering Materials, 2016, 18(1): 148–155.
Laukli H I, Gourlay C M, Dahle A K. Migration of crystals during the filling of semi-solid castings. Metallurgical and Materials Transactions A, 2005, 36: 805–818.
Bi C, Xiong S M, Li X B, et al. Development of a fluid-particle model in simulating the motion of external solidified crystals and the evolution of defect bands in high-pressure die casting. Metallurgical and Materials Transactions B, 2016, 47: 939–947.
Gourlay C M, Dahle A K. Dilatant shear bands in solidifying metals. Nature, 2007, 445: 70–73.
Gourlay C M, Laukli H I, Dahle A K. Defect band characteristics in Mg-Al and Al-Si high-pressure die castings. Metallurgical and Materials Transactions A, 2007, 38: 1833–1844.
Gong N, Nasrin F, Wang Y, et al. Persistent homology on electron backscatter diffraction data in nano/ultrafine-grained 18Cr-8Ni stainless steel. Materials Science and Engineering: A, 2022, 829: 142172.
Jasper R, Ritwik B, George V V, et al. A comprehensive study on solidification (hot) cracking in austenitic stainless steel welds from a microstructural approach. International Journal of Pressure Vessels and Piping, 2021, 194: 104560.
Acknowledgements
This work was financially supported by the National Natural Science Foundation of China (No. 51805389), the Key R&D Program of Hubei Province, China (No. 2021BAA048), the 111 Project (No. B17034), and the fund of the Hubei Key Laboratory of Advanced Technology for Automotive Components, Wuhan University of Technology (No. XDQCKF2021011).
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Meng-wu Wu Male, born in 1984, Ph.D., Associate Professor. Research interests: advanced manufacturing technologies for automotive components.
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Hou, Yy., Wu, Mw., Huang, F. et al. Defect band formation in high pressure die casting AE44 magnesium alloy. China Foundry 19, 201–210 (2022). https://doi.org/10.1007/s41230-022-1220-1
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DOI: https://doi.org/10.1007/s41230-022-1220-1