Control of soundness and mechanical properties in aluminium-silicon-magnesium alloys

Abstract

Previously, specifications for mechanical properties of casting alloys were based
on separately cast test bars. This practice provided consistently reproducible
results; thus, any change in conditions was reflected in changes in the mechanical
properties of the test coupons. These test specimens, however, did not necessarily reflect the actual mechanical properties of the castings they were supposed to represent'. Factors such as section thickness and casting configuration affect the solidification rate and soundness of the casting thereby raising or lowering its mechanical properties in comparison with separately cast test specimens.
In the work now reported, casting shapes were developed to investigate the
variations of section thickness, chemical analysis and heat treatment on the
mechanical properties of a high strength Aluminium alloy under varying chilling
conditions. In addition, an insight was sought into the behaviour of chills under
more practical conditions. Finally, it was demonstrated that additional information
could be derived from the radiographs which form an essential part of the quality
control of premium quality castings.
As a result of the work, it is now possible to select analysis and chilling
conditions to optimize the as cast and the heat treated mechanical properties of
Aluminum 7% Silicon 0.3% Magnesium alloy.

Date of Award	Jun 1973
Original language	English
Supervisor	J.C. Wright (Supervisor) & J.T. Barnby (Supervisor)