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Effect of cooling rate on microstructure and mechanical properties of squeeze cast Al–Cu–Mg alloy

Abstract Castings of Al–Cu–Mg alloy with different section thickness were prepared by gravity casting and squeeze casting, and microstructure and mechanical properties of the castings were studied. The experimental results show that squeeze casting results in considerable microstructure refinement and reduction of shrinkage porosity compared with gravity casting due to a marked increase in cooling rate. Therefore, the density and mechanical properties of the alloy are significantly improved in squeeze castings. With the section thickness increasing, microstructure of the alloy gets coarse due to a reduction in cooling rate, and the mechanical properties decrease monotonously. The composition variation of Cu between different steps in squeeze casting is smaller than that of gravity casting. Gravity casting leads to an inverse segregation of Cu in each step, while squeeze casting causes a normal solute concentration profile through the feeding of solidification shrinkage by applied pressure.