日本金属学会誌

J. Japan Inst. Metals, Vol. 49, No. 9 (1985),
pp. 746-752

Embrittlement of Solidifying Binary Cu-Zn Alloy Castings

Shigeo Oya1, Mitsuhiro Ohtaki1, Masao Kobayashi2 and Keiichi Kobayashi3

1Faculty of Science and Engineering, Waseda University, Tokyo
2Graduate Student, Waseda University, Tokyo. Present address: Central Research Institute, Mitsubishi Metal Co., Saitama
3Graduate Student, Waseda University, Tokyo

Abstract:

Tensile strength and apparent deformation of solidifying binary Cu-Zn alloy castings were studied at various fractions of solid by use of a tensile test apparatus newly designed. The alloys complete solidification through four stages with increasing fraction of solid. The alloys in stage I with fraction of solid up to fa have significant deformation and negligible strength. Those in stage II with fraction of solid fa to fb rapidly lower the deformation. Those in stage III with fraction of solid fb to fc minimize the deformation and have noticeable strength. Those in stage IV with fraction of solid fc or more show rapid increase in both of deformation and strength (fabc). The α -phase alloys containing Zn up to 30 mass% have less apparent deformation in the extended brittle stage III than the β -phase alloys. The peritectic alloy has the maximum apparent deformation. Interdendritic fluid flow plays a significant role in the embrittlement during solidification. Changes in the tensile properties with increase of fraction of solid are explainable by the solid forming process and interdendritic fluid behavior.


(Received 1985/1/11)

Keywords:

embrittlement of solidifying alloys, fraction of solid, apparent deformation of solidifying alloys, tensile strength of solidifying alloys, copper-zinc alloy castings, hot tearing, interdendritic fluid flow


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