Al-Mg-Si-(Cu) 6xxx Series Alloy Selection for Rheo-High Pressure Die Casting

Abstract:

This paper investigates the selection process of Al-Mg-Si-(Cu) 6xxx series alloys when used specifically for rheo-high pressure die casting (R-HPDC). The 6xxx series alloys have been developed as wrought alloys and certain factors must be taken into consideration when utilising them for semi-solid metal processing. It is shown that chemical composition has a significant effect on the solution treatment parameters that should be employed i.e. high Cu and excess Si levels necessitate the use of a two-step solution treatment to reduce incipient melting. This incipient melting is especially severe in areas within the component where liquid segregation occurs, which is a common phenomenon in R-HPDC. However, high Cu and excess Si levels also have advantages: it results in higher T6 strength and Cu-additions have been shown to minimise the negative effects of natural pre-ageing. Therefore, the composition of the alloy must be selected in such a way as to achieve acceptable strength without the dangers of incipient melting in liquid segregated areas. Another important modification of 6xxx series alloys used for R-HPDC that is presented is the addition of Ti to minimise hot tearing.

• Periodical: Advanced Materials Research (Volume 1019)
• Pages: 61-66
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1019.61
• Online since: October 2014
• Authors: Heinrich Möller*, Pfarelo Daswa, Gonasagren Govender
• Keywords: 6xxx Series Aluminium Alloy, Alloy Selection, Heat Treatment, Hot Tearing, Rheo-High Pressure Die Casting (R-HPDC)

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