Effects of stirring parameters on the rheocast microstructure and mechanical properties of aluminum alloy ADC12

Effendy Arif,Hairul Arsyad,Muhammad Syahid,Syaharuddin Rasyid

doi:10.1051/matecconf/201819712004

Abstract

In this study, effects of stirring time and stirring speed on the microstructure of semisolid rheocast (SSR) aluminum alloy ADC12 were examined. The research method was done by gravity casting using a metal mold. The aluminum ADC12 slurry is stirred by a mechanical stirrer (round rod stirrer) at 610OC with a variation of speed 0, 250, 300, 350 rpm for 0, 20, 40, 60 seconds. Furthermore, the aluminum slurry of ADC12 is poured on a metal mold with temperature 600OC. The microstructure characteristics were examined by direct observation using optical microscopy, secondary -Al phase dendrite arm spacing, shape factor, and Si eutectic phase were identified. The mechanical properties were investigated by hardness test and tensile test. A short period of stirring below the liquidus temperature to form a non-dendritic structure. The final morphology of the primary particles after a short period of stirring time has little impact as the stirring time increases. The optimal mechanical properties (hardness and tensile strength) were obtained at 20 seconds of stirring time and 300 rpm of stirring rate.

Highlights

Aluminum alloy processing with semisolid technique is developing rapidly as an alternative to traditional casting and forging processes
In order to improve the mechanical properties of aluminum alloys, a semisolid metal forming process is formed by partial solidification and partial melting where solids are present as nearly perfect spheroidal particles [2]
Sample number 1 has a major particle of dendritic morphology with an average secondary dendritic arm spacing of the α-al (SDAS) of 24.9 μm and a sample of 2-4 has a major particle of dendritic morphology greater than sample 1 with almost the same value

Summary

Introduction

Aluminum alloy processing with semisolid technique is developing rapidly as an alternative to traditional casting and forging processes. The effect of mechanical stirring parameters on the mechanical properties of aluminum and alloying metals has been widely reported in the literature [3,4,5,6,7,8] This literature has been reported generally use mechanical stirrer models round rods of copper or graphite material. As the stirring time increases, the average primary particle size becomes larger It seems that the main effect on the particle growth takes place in the initial stages of solidification by the creation of more driving force for particles growth through increased concentration gradient in front of the solid-liquid interface [10]. The experiment was conducted to study the effect of stirring parameters (time and speed stirring) in the slurry preparation ADC12 aluminum alloy to microstructure and mechanical properties

Preparation of SSR slurry

Mechanical testing and microstructure analysis

Effects of stirring time

Effects of stirring speed

Conclusion