The Effect of SR-Modification Treatment on Porosity Formation of Reduced Pressure 319 Al Alloy Castings

Abstract

The effect of Sr-modification on pore formation in reduced pressure and atmospheric conditions was studied. It was found that in thin wall steel cup conventional specimens, the Sr-modification had no significant effect on pore formation. A new type of metallic cup with a riser was designed for use in a reduced pressure test as a mould. It was designed to improve directional solidification so that no macro shrinkage occurred in test samples. Using this mould, the effect of Sr-modification on pore formation was investigated. The effect of Sr-modification on the increased pore number density and pore volume fraction became significant in both reduced pressure and atmospheric conditions. Also, the results indicate that the effect of Sr-modification on pore formation of reduced pressure samples is not considerable in the melt with a hydrogen content lower than 0.1cc/100g Al.

The effect of Sr-modification on pore formation in reduced pressure and atmospheric conditions was studied. It was found that in thin wall steel cup conventional specimens, the Sr-modification had no significant effect on pore formation. A new type of metallic cup with a riser was designed for use in a reduced pressure test as a mould. It was designed to improve directional solidification so that no macro shrinkage occurred in test samples. Using this mould, the effect of Sr-modification on pore formation was investigated. The effect of Sr-modification on the increased pore number density and pore volume fraction became significant in both reduced pressure and atmospheric conditions. Also, the results indicate that the effect of Sr-modification on pore formation of reduced pressure samples is not considerable in the melt with a hydrogen content lower than 0.1cc/100g Al.

On a étudié l'effet de la modification au Sr sur la formation de pore sous pression réduite et en conditions atmosphériques. On a trouvé que dans les échantillons conventionnels de tasse d'acier à paroi mince, la modification au Sr n'avait pas d'effet important sur la formation de pore. On a conçu un nouveau type de tasse métallique avec une masselotte pour utilisation comme moule dans un test à pression réduite. On l'a conçue pour améliorer la solidification directionnelle de telle sorte qu'il ne se produise pas de retassure macroscopique dans les échantillons. En utilisant ce moule, on a étudié l'effet de la modification au Sr sur la formation de pore. L'effet de la modification au Sr sur l'augmentation de la densité du nombre de pores et sur la fraction volumique des pores était aussi important sous pression réduite qu'en conditions atmosphériques. Également, les résultats indiquent que l'effet de la modification au Sr sur la formation de pore des échantillons à pression réduite n'est pas très important dans le bain ayant un contenu en hydrogène plus faible que 0.1 cc/100 g Al.