Thermal Flow-Solidification Simulation and Analysis of Strip Defects in Vertical Twin-Roll Casting of Magnesium Alloy

2015 ◽  
Vol 833 ◽  
pp. 15-18 ◽  
Author(s):  
Zhi Pu Pei ◽  
Dong Ying Ju ◽  
Hong Yang Zhao ◽  
Xiao Dong Hu

A quantitative understanding of the twin-roll casting process is required to get high quality as-cast magnesium alloy strips. In this paper, a thermal flow-solidification simulation was carried out to study the behavior of casting zone and its effects on defects generation deeply. Results show that a lower pouring temperature is not suitable for producing defect-free magnesium alloy strips. With increasing of the casting speed, the tendency of cracks formation will getting smaller because of the more uniform temperature distribution. A low pool level leads to a small metal-roll contact area, and a sharp temperature distribution will generates under this situation, which is not good for strips quality.

2012 ◽  
Vol 17 (4) ◽  
pp. 479-483 ◽  
Author(s):  
Xiao-dong Hu ◽  
Dong-ying Ju ◽  
Hong-yang Zhao

2013 ◽  
Vol 395-396 ◽  
pp. 209-213
Author(s):  
Zhi Pu Pei ◽  
Hong Yang Zhao ◽  
Xiao Dong Hu ◽  
Dong Ying Ju

Thermal flow finite element simulation was carried out to deeply understand the solidification and deformation phenomena of magnesium alloy in molten zone during twin-roll casting process. The results show that temperature near the nip of the rolls is about 680K based on current conditions, and there are two vortexes in the molten pool during casting, a peak formed at solidus. Due to the metal flows in molten pool and relative rotates of the rolls, temperature field of molten zone is different from normal casting, which will cause the solidification structure changes. An experiment by using a vertical type twin-roll caster was also conducted, and the amount of deformation bands at the joint line is larger than that at the two sides. Substructures can be found due to dynamic recrystallization during casting process.


2007 ◽  
Vol 539-543 ◽  
pp. 5037-5043 ◽  
Author(s):  
Xiao Dong Hu ◽  
Dong Ying Ju ◽  
Hong Yang Zhao

Twin- roll casting of magnesium alloys is a rapidly solidifying process, which can directly produce thin strips from molten metal. In this paper, based on a pilot vertical type twin-roll caster, 3D models of twin-roll casting process were used for simulation of thermal flow and solidification on depending of casting speed, molten pool level and pouring temperature. The effect of side dams on thermal flow behavior was also considered. Based on the analyzed results, a proper concave slot nozzle was designed to compensate temperature variation across the width of strip. Comparing with parallel type slot nozzle, it can adjust temperature distribution along the roll width continuously by adopting proper concave curves, which is more flexible than rectification boards delivery system. Strips of magnesium alloy AZ31 were produced in the pilot caster with the concave slot nozzle. The experiments show that surface quality of as cast strip was improved by using the new type of nozzle.


2009 ◽  
Vol 209 (5) ◽  
pp. 2321-2328 ◽  
Author(s):  
Jian Zeng ◽  
Roger Koitzsch ◽  
Herbert Pfeifer ◽  
Bernd Friedrich

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