研究論文
AC2B合金のひけ性と共晶組織の改良に及ぼすPとNaの影響
2017 年 89 巻 9 号 p. 563-569
詳細
2017 年 89 巻 9 号 p. 563-569
When toughness or corrosion resistance as high as that in AC4CH alloy cannot be obtained for aluminum alloy casting, inexpensive alloys such as AC2A or AC2B may be used in some cases. Modification treatment is applied to these alloys, and this is expected to prevend interior shrinkage rather than improve toughness. However, there are few reports on the effects of modification treatment on shrinkage characteristics. Therefore, in the present study, Na, which is considered to have a high modification effect, was varied at 0, 30, and 60 ppm for AC2B alloy. on the other hand, the P content ranged from 7 to 27ppm. Interior and exterior shrinkage rates were measured by the Tatur mold method. Shrinkage formed on the longitudinal section of the specimens and microstructures were observed.
The results revealed that the threshold of P content for shrinkage transition from external shrinkage to interior shrinkage was 10ppm. Porosity was observed in all specimens. Shrinkage porosity formed in almost all specimens, but in comparison with 8ppm, P content was small, Na content was not observed in 33ppm specimens, which are indicated to have the appropriate quantity. The modification / un-modification threshold of the eutectic structure was Na/P = 2.2.
