摘要
宏观偏析是金属凝固过程中产生的不可避免的缺陷,且难以通过热处理消除,会导致金属制品不同部位的组织和力学性能有差异。因凝固时间长且熔体流动复杂,大型铸锭的宏观偏析尤为严重。A型偏析的形成主要与夹杂物上浮有关,而V型偏析的形成机制较为复杂,普遍认为形成于铸锭凝固的后期。连铸过程中采用脉冲磁致振荡技术可大大减轻大型铸锭的宏观偏析。研究铸锭宏观偏析的主要方法有铸锭解剖、实验室模拟和数值模拟等。因大型铸锭宏观偏析的试验研究极为困难,数值模拟已成为重要的研究手段。现有的模拟大型铸锭宏观偏析形成的数学模型有枝晶模型、两相和多相模型、连续介质模型、体积平均模型及多尺度多相模型等,但宏观偏析形成的数值模拟仍有很多问题有待解决,如关于A型和V型偏析的形成机制尚无定论,宏观偏析形成的数值模拟需要的参数匮乏,需要建立模型数据库等。
Macrosegregation is an unavoidable defect produced during metal solidification and difficult to be eliminated by heat treatment,will result in differences in microstructure and mechanical properties of different parts in a metal product.The macrosegregation in heavy ingot is particularly serious because of its long solidification time and complex melt flow.The formation of A-type macrosegregation is concerned mainly with floating of the inclusions,whereas the mechanism of formation of V-type is more complex, and generally considered to form in the late stage of solidification process.The use of a pulsed magneto-oscillation technology during the continuous casting may render macrosegregation in heavy ingot much less.The principal methods used to investigate macrosegregation in ingot include anatomizing ingot, simulation in laboratory and numerical simulation.Because the macrosegregation in heavy ingot is extremely difficult to be studied by testing,the numerical simulation has been become an important research way.The existing mathematical models used to simulate the formation of macrosegregation in ingot involve dendrite model,two-phase and multi-phase models,continuous medium model,volume average model,and multi-scale multi-phase model.However, there are still many problems to be solved in the numerically simulating formation of macrosegregation,for example,there being no a final conclusion on the mechanism of formation of A-type and V-type macrosegregations,deficient parameters required for numerically simulating formation of macrosegregation, the need for establishing the model database,etc.
作者
张帆
殷子豪
杨宇乾
仲红刚
ZHANG Fan;YIN Zihao;YANG Yuqian;ZHONG Honggang(Center for Advanced Solidification Technology,Shanghai University,Shanghai 200444,China)
出处
《上海金属》
CAS
2022年第1期74-80,87,共8页
Shanghai Metals
基金
国家重点研发计划(No.2017YFB0701802)
河北省重点研发计划(No.203110060)。
关键词
大型铸锭
宏观偏析
数值模拟
heavy ingot
macrosegregation
numerical simulation
