Effects of different casting mould cooling rates on microstructure and properties of sand-cast Al-7.5Si-4Cu alloy

• Published in: China foundry Vol. 10; no. 6; pp. 396 - 400
• Main Authors: Liu, Guanglei, Si, Naichao, Sun, Shaochun, Wu, Qinfang
• Format: Journal Article
• Language: English
• Published: School of Materials Science and Engineering, Jiangsu University, Zhejiang 212013, China%Suzhou Mingzhi Technology Ltd., Suzhou 215217, China 01.11.2013; Foundry Journal Agency
• Subjects: Al-7.5Si-4Cu alloy; Aluminum base alloys; Cooling rate; fitting analysis; Mechanical properties; Microstructure; Molds; properties and microstructure; Sand casting; Sands; Wall thickness; cooling rate; properties and microstructure; fitting analysis; Al-7.5Si-4Cu alloy
• ISSN: 1672-6421; 2365-9459

In this work, Al-7.5Si-4Cu alloy melt modified by Al-10Sr, RE and Al-5Ti-B master alloys was poured into multi-step moulds made from three moulding sands, including quartz, alumina and chromite, to Investigate comparatively the effects of different cooling rates of the casting mould on the alloy's microstructures and mechanical properties. The results show that with an increase in wall thickness, the cooling rate decreases, the dendrite arm spacing (DAS) increases significantly and the mechanical properties decrease steadily. The elongation is more sensitive to the cooling rate than the tensile strength. No obvious trend of the effect of wall thickness on hardness of the alloy was found. When the cooling rate is at its greatest, the microstructures and mechanical properties are the best when using chromite sand. The improvement of the properties is mainly attributed to the decrease of the DAS, the grain refinement and the metamorphic effect. Each of the three has a strong impact on the microstructures. Furthermore, a series of fitting models was established based on the data of the DAS to predict the mechanical properties of the multivariate sand-cast Al-7.5Si-4Cu alloy,