| Al-Si alloys have been modified by Na. However, because of fading tendency of Na, modification of Al-Si alloys by Sr is recently being researched. Besides Na addition, high colling rate also results in modification. Accordingly, this experiment was performed to study the modification of Al-Si alloys by Sr in permanent mold casting and was focused to Sr content for complete modification, improvement of mechanical properties, thermal analysis and shrinkage. At 0.3% Sr, when the mold is preheated to 200℃, complete modification was accomplished and mechanical properties were considerably improved. Thermal analysis curve and shrinkage tendency may be used for determining the degree of modification in the permanent mold casting. |
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