The role of double oxide film （bifilm） defects in the formation of gas porosity in commercial purity and Srcontaining AI alloys was investigated by means of a reduced pressure test （RPT） technique. The liquid meta...The role of double oxide film （bifilm） defects in the formation of gas porosity in commercial purity and Srcontaining AI alloys was investigated by means of a reduced pressure test （RPT） technique. The liquid metal was poured from a height into a crucible to introduce oxide defects into the melt. The melt was then subjected to different ＂hydrogen addition＂ and ＂holding in liquid state＂ regimes before RPT samples were taken. The RPT samples were then characterized by determining their porosity parameters and examining the internal surfaces of the pores formed in them by scanning electron microscopy. The results indicated oxide defects as the initiation sites for the growth of gas porosity, both in commercial purity and Sr-containing AI alloys. The results also rejected reduction of the surface tension of the melt, increase in the volumetric shrinkage and reduction in interdendritic feeding as the possible causes of an increase in the porosity content of the AI castings modified with strontium. The change in the composition of the oxide layers of double oxide film defects was suggested to be responsible for this behaviour.展开更多
熔体质量和工艺裂边是影响5005合金铸轧产品质量的重要因素之一。分析了5005合金熔体气、渣来源,阐明了熔体精炼机制,通过工艺优化,使熔体中氢含量降至0.12 mL/(100 g Al);同时,通过调整铸轧区长度、改进铸嘴耳子结构,使5005合金铸轧带...熔体质量和工艺裂边是影响5005合金铸轧产品质量的重要因素之一。分析了5005合金熔体气、渣来源,阐明了熔体精炼机制,通过工艺优化,使熔体中氢含量降至0.12 mL/(100 g Al);同时,通过调整铸轧区长度、改进铸嘴耳子结构,使5005合金铸轧带材的裂边减至7.5 mm左右。铸轧带材的产品质量明显提高。展开更多
文摘The role of double oxide film （bifilm） defects in the formation of gas porosity in commercial purity and Srcontaining AI alloys was investigated by means of a reduced pressure test （RPT） technique. The liquid metal was poured from a height into a crucible to introduce oxide defects into the melt. The melt was then subjected to different ＂hydrogen addition＂ and ＂holding in liquid state＂ regimes before RPT samples were taken. The RPT samples were then characterized by determining their porosity parameters and examining the internal surfaces of the pores formed in them by scanning electron microscopy. The results indicated oxide defects as the initiation sites for the growth of gas porosity, both in commercial purity and Sr-containing AI alloys. The results also rejected reduction of the surface tension of the melt, increase in the volumetric shrinkage and reduction in interdendritic feeding as the possible causes of an increase in the porosity content of the AI castings modified with strontium. The change in the composition of the oxide layers of double oxide film defects was suggested to be responsible for this behaviour.
文摘熔体质量和工艺裂边是影响5005合金铸轧产品质量的重要因素之一。分析了5005合金熔体气、渣来源,阐明了熔体精炼机制,通过工艺优化,使熔体中氢含量降至0.12 mL/(100 g Al);同时,通过调整铸轧区长度、改进铸嘴耳子结构,使5005合金铸轧带材的裂边减至7.5 mm左右。铸轧带材的产品质量明显提高。
