型壳加热温度对单晶高温合金显微组织及"雀斑"形成的影响
Effects of shell mold heating temperature on microstructures and freckle formation of single crystal superalloys
王志成 1李嘉荣 1刘世忠 1杨万鹏 1王效光1
作者信息
- 1. 北京航空材料研究院先进高温结构材料重点实验室,北京 100095
- 折叠
摘要
利用所设计的阶梯试样进行定向凝固试验和模拟,研究定向凝固过程型壳加热温度对单晶高温合金铸件显微组织和"雀斑"形成的影响.分析糊状区的温度场及形貌.结果表明,升高型壳加热温度,一次和二次枝晶间距减小,糊状区液相的渗透率和对流通道的宽度降低,"雀斑"形成倾向性降低,"雀斑"宽度减小,"雀斑"区域枝晶碎片减少.此外,随着型壳加热温度的升高,糊状区液相冷却速率增加,糊状区熔体的冷却时间减少,液体流动对枝晶的破碎程度得到削弱,这进一步降低单晶高温合金铸件"雀斑"形成的倾向性.
Abstract
To study the effects of shell mold heating temperature on the microstructure and freckle formation of single crystal superalloys,the directional solidification experiment and simulation were conducted with designed stepwise specimens.The temperature field and morphology of mushy zone were analyzed.The results show that the primary and secondary dendrite arm spacings both decrease with the rise of shell mold heating temperature.This reduces the permeability of the liquid in the mushy zone and the width of the thermal-solutal convection channel,which reduces the formation tendency of freckles,the width of freckles and the number of dendritic fragments in freckled areas.In addition,with the increase of shell mold heating temperature,the cooling rate of liquid in the mushy zone increases,which reduces the cooling time of the melt in the mushy zone,weakens the breaking capability of liquid flow to the dendrite,and further reduces the tendency of freckle formation in single crystal superalloy castings.
关键词
单晶高温合金/"雀斑"形成/型壳加热温度/定向凝固/数值模拟Key words
single crystal superalloy/freckle formation/shell mold heating temperature/directional solidification/numerical simulation引用本文复制引用
基金项目
国家科技重大专项(2017-VI-0001-0070)
国家科技重大专项(J2019-Ⅲ-0008-0052)
出版年
2024
NETL
NSTL
万方数据