Microstructural evolution and mechanical properties of thixoformed Al-Si-Cu alloy connecting rods

Abstract

Connecting rod is considered one of the most crucial mechanical components of internal combustion engines. The materials and processing methods of such components are the matter of research that mainly focuses on the enhancement of its performance while contributing to the overall weight reduction of the vehicles. They should have very high strength to ensure long service life because of the high levels of cyclical loading they are subjected to. A lot of effort has been put to manufacture such components via the use of thixoforming as this method could enhance the mechanical properties by minimizing the defects existed in as-received alloys. In this study, the thixoforming process of Al-Si-Cu aluminium alloy was carried out. The cooling slope method was used to prepare the feedstock for thixoforming. The results revealed the superior integrity and quality concerning the performance of alloys produced by the thixoforming processing. Microstructure studies show the enhancement and the reduction in casting porosity with the transformation of dendritic arms to mostly globular of α-Al. Subsequently, mechanical properties of the thixoformed parts were remarkability improved and reached the values of 107 HV, 197 MPa and 250 MPa for hardness, yield stress, and ultimate tensile strength, respectively.