Grain refining versus electromagnetic stirring techniques: microstructural and mechanical characterization of the thixoforged Al4Si2.5Cu alloy

ABSTRACT

The objective of this work was to evaluate the thixoformability of the Al4Si2.5Cu alloy under two different production routes: the techniques via grain refining and via electromagnetic stirring, ranging from obtaining the alloy to its microstructural and mechanical characterization after the thixoforging process in a mechanical eccentric press. The alloy was subjected to globularization heat treatments promoting the globularization of the primary phase particles for 0s and 210s in the 45% solid fraction and the thixoforged sequence. The thixoforging tests showed that the necessary force to close the die is practically constant, regardless of the globularization time, remaining around 70 kN, using less than a third of the press capacity. Regarding its morphology for both production routes, it presented a globular morphology for both heat treatment times. The thixoforged parts showed good formability, filling the entire matrix and reproducing its geometry, in addition to presenting good mechanical properties through tensile tests, that is, the limit value of tensile strength, especially when using the production route via electromagnetic stirring, presented values close to at 200 MPa. It demonstrates that the alloy becomes suitable for thixoforming processes.

Keywords
Thixoforming; Grain refining; Electromagnetic stirring; Al4Si2.5Cu alloy