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Metallurgical and Materials Transactions A

, Volume 32, Issue 3, pp 525–532 | Cite as

The effect of solution heat treatment and quenching rates on mechanical properties and microstructures in AlSiMg foundry alloys

  • L. Pedersen
  • L. Arnberg
Article

Abstract

Four common AlSiMg foundry alloys have been solution heat treated at 813 K, quenched, and immediately aged at 423 K for up to 240 minutes. The mechanical properties are found to be related to the amount of Mg and Si in the alloys. A high strength is obtained after only 60 minutes of solution heat treatment, indicating that the solid solution is rapidly saturated on Mg and Si. The ductility is very much related to the amount of silicon present and the refinement of the silicon crystals within the eutectic areas, since silicon crystals are observed to crack when load is applied. Thus, a well-modified structure is the best way to obtain high ductility. Reduced quencing rates after solution heat treatment lead to a lower strength, since a lower number of hardening β′-Mg2Si precipitates are formed. The ductility of alloys with 0.6 wt pct Mg is increased with a reduced quenching rate. A more ductile matrix corresponding to the lower amount of hardening precipitates can explain this. Alloys with 0.2 wt pct Mg remain relatively unchanged. A hypothesis that may explain this phenomenon is the precipitation of brittle silicon or formation of coarse Mg2Si within the dendrites.

Keywords

Ductility Material Transaction Ultimate Tensile Strength Silicon Crystal Solution Heat Treatment 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© ASM International & TMS-The Minerals, Metals and Materials Society 2001

Authors and Affiliations

  • L. Pedersen
    • 1
  • L. Arnberg
    • 2
  1. 1.Elkem Aluminium ListaFarsundNorway
  2. 2.Department of Materials Technology and ElectrochemistryThe Norwegian University of Science and TechnologyTrondheimNorway

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