Prevention of macrodefects in squeeze casting of an Al-7 wt pct Si alloy
The squeeze casting of an Al-7 wt pct Si alloy was carried out in order to investigate the conditions for the formation and the prevention of macrosegregation. The effects of process parameters such as applied pressure, die temperature, pouring temperature, delay time, degassing, and inoculation on the formation of macrosegregation were investigated, in correlation with the evolution of macrostructure and shrinkage defects. Three critical applied pressures were defined, based on the experimental results for the squeeze-cast Al-7 wt pct Si. The first is the critical applied pressure under which shrinkage defects form (P{sub SC}). The second is the critical applied pressure above which macrosegregates form (P{sub MS}). The third is the critical applied pressure above which and under which minor segregation forms. (P{sub m} and P{sub MS}, respectively). With the concept of these three critical pressures, an experimental diagram describing the optimum process conditions was proposed for obtaining sound squeeze castings. It was concluded that sound castings without macrosegregation and shrinkage defects can only be obtained when the applied pressure is in the range where P{sub SC} < P < P{sub m} (<P{sub MS}). Both degassing and inoculation treatments greatly enhanced the soundness of the castings. It was also found that the pouring temperature and the delay time should not exceed T{sub D-critical} and t{sub D-critical}, respectively, in order to achieve sound castings.
- Research Organization:
- Yonsei Univ., Seoul (KR)
- OSTI ID:
- 20076005
- Journal Information:
- Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science, Vol. 31, Issue 2; Other Information: PBD: Apr 2000; ISSN 1073-5615
- Country of Publication:
- United States
- Language:
- English
Similar Records
Infiltration of Al{sub 2}O{sub 3} short-fiber preforms during squeeze
ULTRA HIGH PRESSURE CASTING. Interim Report No. 2 Covering Period March 1, 1959 to May 30, 1959