Effects of Cooling Rate on High-temperature Mechanical Properties of A356 Alloys |
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Authors: | Zhang Kai Sun Yucheng Wang Suolin Zheng Hongliang Xu Rongfu Tian Xuelei Key Laboratory for Liquid-Solid Structural Evolution Processing of Materials Sh ong University Jinan China |
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Affiliation: | Zhang Kai,Sun Yucheng,Wang Suolin,Zheng Hongliang,Xu Rongfu,Tian Xuelei Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education),Shandong University,Jinan 250061,China |
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Abstract: | High temperature mechanical properties of A356 alloy castings under different solidification cooling rates have been studied and the influence of cooling rates on secondary dendrite arm spacing (SDAS) and mechanical properties has been discussed. To get different cooling rates, three different types of mold—green sand, green sand with chill and permanent mold, were used to pour castings which would subsequently be machined into tensile test and metallographic specimens. The temperature curves of castings’ solidification in three different mold were recorded using thermal couples, which would be used to calculate their corresponding cooling rates. Tensile tests were carried out at 20, 200, 300, 400 and 500 ℃ and then mechanical properties, such as tensile strength, yield strength, elongation, of specimens from different mold types at different test temperatures were obtained. And SDAS of different specimens were measured using optical metallographic photos. From integrated analysis of all those results, following conclusions could be reached. The relationship between SDAS and cooling rates is negative, and the quantitative relationship has been obtained through data fitting analyzing. Generally speaking, tensile strength and yield strength decease as the temperature elevates while elongation behaves in the contrary trend. Through the regression analysis of SDAS, mechanical properties and temperature, the relationship among them is obtained, which makes quantitative prediction of A356 alloy’s mechanical properties at different temperatures with different solidification cooling rates be possible. |
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Keywords: | A356 alloy high temperature mechanical properties cooling rate SDAS |
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