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Title: Factors affecting the production of aluminium alloy automotive wheels by the low pressure die casting process
Author: Carbin, R.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1994
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It was found that the addition of strontium modifier to the melt significantly altered both the euctectic silicon particle size and morphology and the porosity size and distribution developed on solidification. The eutectic silicon phase was transformed from one of large, elongated interconnected flakes to that to much finer more rounded particles. Porosity size and distribution was found on modification to change from that of many fine pores distributed across the whole sample cross section to that of very much fewer, widely dispersed but larger pores separated by sound material. Addition of titanium based grain refining master alloy to the melt was found to produce a different effect on porosity distribution depending on what form of addition was made. A binary Al-6Ti addition was found to cause a sharp increase in the number of pores developed, when compared to the modified only material. A ternary Al-5Ti-1B addition, on the other hand, was found to produce only a modest increase in the number of pores developed. It was also found that for the same melt hydrogen content, TiAl grain refined melts produced samples that were systematically more porous, as assessed by density, when compared to TiBAl grain refined samples. Stirring of the melt immediately prior to the obtaining of the test castings was found to cause an increase in the number of pores in TiBAl refined melts, and to cause a partial loss of modification, while stirring had less effect for either TiAl refined or modified only melts. With regard to rim cooling method, it was found that the technique producing the harshest cooling resulted in the production of the finest microstructure, not only in the rim region, but across the whole wheel section. It was found that dendrite arm spacing was finer, and the occurrence of damaging acicular intermetallic particles was much reduced.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available