Solidification Microstructure and Critical Conditions of Shrinkage Porosity Generation in Die Casting Process of JIS-ADC12 (A383) Alloy

Abstract

Differential thermal analysis (DTA), analyses of unidirectional solidification process and die casting process, and computational numerical simulations were conducted for JIS-ADC12 (A383) alloy to investigate the generation conditions of shrinkage porosities which occasionally appear in JIS-ADC12 die castings and affect the quality of products. The crystallization temperature of the primary alpha phase and AlSi binary eutectic phase are estimated to be 856 and 838 K from DTA, respectively. The multi-phase eutectic reaction of JIS-ADC12 alloy starts from 826 K, and finishes at 801 K. The primary alpha dendrites are clearly observed in the unidirectional solidification microstructures, and the relationship between the secondary dendrite arm spacing 2 and the local solidification time ¿ f is expressed by the following equation:

Archives of Foundry Engineering

“…In our previous study where high-strength cast aluminum alloy was created, it was clarified that the solid solution process could be removed to achieve the precipitation hardening of high-pressure die-casting aluminum alloys, [9]. The solid solution process can be replaced by a rapid solidification process of high-pressure diecasting [10,11], even though the proper cooling rate of the solidification process has not been clarified. This information is important to make high-strength cast Al alloy via precipitation hardening without a solid solution process of T6 treatments.…”

Effects of Processing Parameters on Microstructure and Properties of Aluminum-Silicon Alloy ADC12

“…There are many defects which can be found in a pressure die casting method such as gas porosities, shrinkage cavities (open shrinkage, internal shrinkage and shrinkage porosity). In particular, shrinkage porosity is one of the predominant defects resulting in a drawback to mechanical properties of alloy parts [3].…”