Scalable Ultrasound-Assisted Casting of Ultra-large 2219 Al Alloy Ingots
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s://doi.org/10.1007/s11661-018-5097-y The Minerals, Metals & Materials Society and ASM International 2019
ZHILIN LIU is with the State Key Laboratory of High Performance Complex Manufacturing, College of Mechanical and Electrical Engineering, Central South University, Changsha, 410083, P.R. China, with the IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid, Spain, and also with Light Alloy Research Institute, Central South University, Changsha, 410083, P.R. China. Contact e-mail: [email protected] RUIQING LI and RIPENG
METALLURGICAL AND MATERIALS TRANSACTIONS A
Due to the light-weight properties of aluminum, ultra-large Al alloy ingots are in high demand for the manufacture of special large metallic components for the transportation, aerospace, automobile, and construction industries. In many commercial applications, the use of power ultrasound can promote activation, degassing, filtration, non-dendritic solidification, semisolid deformation, and emulsification.[1] Ultra-large Al alloy ingots can usually be obtained by ultrasonic melt treatment (UST) integrated with direct-chill (DC) casting.[1–3] The resulting uniform equiaxed grain structures, with an acceptable level of solute segregation, are particularly desirable for tailoring of downstream formability and mechanical properties.[1,3,4] For ultralarge metal casting, the ultrasonic field should be scaled up using multiple sonotrodes to achieve adequate cavitation of the melt. Over the past 60 years, a few well-recognized mechanisms or theories have been developed to rationalize the process of ultrasonic refinement.[1,3–13] These explanations, which were mainly based on results of experiments carried out on laboratory-scale metallic ingots, can be simplified into three categories: (1) cavitation-enhanced nucleation[6,8,12]; (2) cavitation-induced fragand (3) streaming-generated mentation[10,11,13]; homogenization.[3,7] Most laboratory-scale metallic ingots used in these studies were made via single power ultrasound, such as those of an Al-Si alloy (F 100 mm 9 70 mm),[14] Al-Ti alloy (F 85 mm 9 90 mm),[15] Ti-Al alloy (F 20 mm 9 50 mm),[16] stainless steel (F 26 mm 9 30 mm),[17] ZK60 alloy (F 255 mm),[18] Mg-Ni-Y alloy (F 60 mm 9 80 mm),[19] magnesium alloy (F 70 mm),[20] and Zn (F 60~90 mm 9 95 mm). [21]Unfortunately, only a few publications concerning ultra-large Al alloy casting have been reported in the last two decades.[1,3,4,22] Eskin et al. contributed pioneering exploration in the ultrasound-assisted DC casting of large ingots (F 1200 mm 9 ~3000 mm for 2324 Al alloy[1,4]), followed by work of Li et al. (F 650 mm 9 4800 mm for 2219 Al alloy[3]). More recently, Li et al. tried to manufacture an ultra-large 2219 Al alloy ingot using in-house DC casting.[22] They successfully obtained a 2219 Al alloy ingot (F 1250 mm 9 3300 mm); however, severe macrosegregation occurred because the ultrasonication was not scalable.[22] The present work investigated scalable ultrasound-assisted DC casting of ultra-large 2219 Al alloy ingots (diameter of 1250 mm
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