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金属学报  2016, Vol. 52 Issue (12): 1510-1516    DOI: 10.11900/0412.1961.2016.00075
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固态补缩机制及其在大高径比铸件上的应用*
陈龙飞,栾义坤(),李殿中,李依依
中国科学院金属研究所沈阳材料科学国家(联合)实验室, 沈阳 110016
SOLID FEEDING MECHANISM AND ITS APPLICA-TION ON CASTINGS WITH LARGE HEIGHT-TO-DIAMETER RATIO
Longfei CHEN,Yikun LUAN(),Dianzhong LI,Yiyi LI
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
引用本文:

陈龙飞,栾义坤,李殿中,李依依. 固态补缩机制及其在大高径比铸件上的应用*[J]. 金属学报, 2016, 52(12): 1510-1516.
Longfei CHEN, Yikun LUAN, Dianzhong LI, Yiyi LI. SOLID FEEDING MECHANISM AND ITS APPLICA-TION ON CASTINGS WITH LARGE HEIGHT-TO-DIAMETER RATIO[J]. Acta Metall Sin, 2016, 52(12): 1510-1516.

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摘要: 

鉴于液态补缩机制不能解决大高径比铸件中心缩孔疏松缺陷, 提出了固态补缩机制. 通过分析金属液静水拉力对内孔形核和固相屈服变形的作用, 阐明了固态补缩机制的原理, 并得出了影响铸件固态补缩能力的主要因素: 液体破裂压力值、金属液气体含量以及固相屈服强度. 在此基础上, 提出了降低铸件在径向上的温度梯度是减少大高径比铸件缩孔疏松缺陷的有效方法. 最后, 设计了铸件在不同模具温度下凝固的验证实验, 证实了固态补缩对于减少大高径比铸件缩孔疏松的作用.

关键词 铸件,缩孔疏松,固态补缩,静水拉力    
Abstract

Shrinkage porosity is one of major defects in castings, which seriously influences the quality of the castings. In general, the common method to eliminate this defect is to increase the liquid feeding ability of the casting through setting a riser in the corresponding position. However, for the casting with large height-to-diameter ratio, narrow and long feeding channel increases the flow resistance of the liquid metal in the late stage of the solidification. It is difficult to achieve a long-range liquid feeding, and the effect of the feeding is very little. Therefore, the penetrated shrinkage porosity in axis is frequently produced in the continuous casting ingots with large height-to-diameter ratio and large cross-section. As the liquid feeding mechanism has no effect on this problem, the solid feeding mechanism is proposed. First, the solid feeding mechanic is clarified by analyzing the effect of the hydrostatic tense stresses on the pore formation and the solid deformation. In addition, the ability of the solid feeding is determined by the value of the fracture of liquids, the content of the gas solute in liquid metal and yield strength of the solid. Then on the basis of this mechanism, reducing the temperature gradient in the radial direction of the casting is proposed to enhance the solid feeding ability. Finally, a verification experiment was conducted, and the results proved the function of the solid feeding on eliminating the shrinkage porosity defects.

Key wordscasting,    shrinkage porosity,    solid feeding,    hydrostatic tension
收稿日期: 2016-03-09     
基金资助:* 国家自然科学基金资助项目 51304185
图1  固相塑性变形与内孔形核交互效应的示意图
图2  铸件的受力示意图
图3  铸件中心缩孔疏松缺陷分布
图4  不同孔隙率下铸件的缩孔疏松分布
图5  凝固过程中温度差(ΔT)随铸件中心点温度(Tm)的变化
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