摘要
铝及其合金在熔炼过程中,往往存在吸氢现象。当熔体温度下降时,氢在熔体中的溶解度下降,会从熔体中析出,导致铸锭或工件产生气孔、疏松等缺陷。采用不同模具预热温度浇注和减压凝固,分析了模具预热温度对熔体中氢扩散速度及扩散距离的影响,凝固压强对氢气泡临界形核半径和长大的影响。结果表明,低的模具预热温度抑制熔体中氢的扩散和析出;凝固压力大时氢气泡的临界形核半径较大,抑制气泡的形核和长大。所以低的模具预热温度和高的凝固压强可使氢固溶在铝合金中,从而提高其组织的致密性。
There always exists the phenomenon of hydrogen absorption in ahuninum alloy melt. When melt temperature dropped, the solubility of hydrogen in melt decreased and the hydrogen precipitated fi＇om melt, which resulted in the blowhole and porosity in cast ingots or workpieces. Different monld preheating temperatures and decompression solidification were used in casting, the effect of mold preheating temperature on the diffusion rate and diffusion distance of hydrogen, the solidification presstire on the critical nucleation radius and growth of hydrogen bubble were analyzed. The results show that hydrogen diffusion and precipitation was inhibited at low mold preheating temperature, high solidification pressure produced large critical nucleation radius of hydrogen bubble and restrained the nucleation and growth of gas bubble. Hydrogen was dissolved in aluminum alloy melt and the compactability of the structure was improved in low mould preheating temperature and high solidification pressure.
出处
《铸造》
CAS
CSCD
北大核心
2012年第10期1172-1176,共5页
Foundry
关键词
A356铝合金
析氢动力学
减压凝固
模具预热温度
A356 aluminum alloy
kinetics of hydrogen evolution
decompression solidification
mould preheating temperature
