Determination of the Modified Hall-Petch Equation Constants and the Relationship Between the Microstructure and Mechanical Properties of AS7U3G Alloy

Authors

1 1. Department of Materials Engineering, Isfahan University of Technology, Isfahan, Iran.

2 2. Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran.

Abstract

Mechanical properties of the alloys are a strong function of the average silicon particles size and the secondary dendrite arm spacing (SDAS). Modified Hall-Petch equation expresses the effects of these two microstructural parameters on the yield strength and ultimate tensile strength of the Al-Si based alloys. These microstructural parameters depen on parameters such as chemical composition, cooling rate and melt treatment. In this study, the effect of cooling rate on the  equation constants of the alloy were determined. For this purpose, the alloy was poured at 750 °C in three different molds including a sand mold, a preheated steel mold, and a water cooled steel mold. The Thermal and microstructural analysis showed that the cooling rate in the metal mold was 15.7 times higher than that of the sand mold, which resulted in a decrease of the SDAS from 54 micrometers to 17 micrometers. It was also found that by reducing the SDAS from 45 micrometers to 17 micrometers, the yield strength and tensile strength were increased by 16.5% and 6.5%, respectively. The modified Hall-Petch equation constants and the microstructure-mechanical properties relationships were then established by the microstructural and tensile test studies.

Keywords

References

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Journal of Advanced Materials in Engineering (Esteghlal)
Volume 37, Issue 4
March 2019
Pages 91-100

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