The role of solidus velocity in the feeding behaviour of Al7si0.3Mg alloy plate castings

✍ Scribed by Y.W. Lee; E. Chang; C.F. Chieu

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 677 KB
• Volume: 124
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/0921-5093(90)90153-t

✦ Synopsis

The present study attempts to investigate systematically the combined influence of feeder size and casting length on the feeding behaviour orAl-7Si-0.3Mg alloy. The castings were examined by X-ray radiography and density measurement to determine their feeding efficiency. During solidification, thermal data were taken to analyse the thermal gradient G, the local solidification time t, the ratio G/t and the solidus velocity V s. The purpose was to characterize the significance of the solidus velocity compared with other parameters in predicting the formation of porosity.

The solidus velocity is proposed as a useful parameter to characterize the feeding of Al-7Si-O.3Mg alloy in which measurement of the thermal gradient at the final stage of solidification becomes difficult. Both riser size and length of casting exert a large influence on the solidus velocity from the free end to the riser. The solidus velocity is slow at the free end; it increases to a maximum at a position about one-third of the distance from the riser end and then slows down again when approaching the riser. Good prediction of V s on porosity content is obtained in this experiment.