Çok yönlü sıcak dövme işleminin Al-7Si-4Zn-3Cu alaşımının mekanik ve tribolojik özelliklerine etkisi
Gazi Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi
Highlights: Graphical/Tabular Abstract Multi-Directional forging resulted in the breaking up the silicon particles and the elimination of dendritic structure Multi-Directional forging increased the tensile properties and ductility of the tested alloy Multi-Directional forging increased the friction coefficient and mass loss of the of the tested alloy Figure A. The curves showing the mass loss of the alloy versus with apllied forging cyle and load with a reperanstative image of its worn
... face Purpose: The purpose of this study is to investigate the effect of multi-directional hot forging on the mechanical and tribological properties of the Al-7Si-4Zn-3Cu alloy. Theory and Methods: The main theory of this study is to improve the strength, ductility and wear performance of the Al-7Si-4Zn-3Cu with severe plastic deformation technique. For this aim, the alloy was forged in open die on three main axis at 200 °C using hydraulic press with capacity of 150 tons. The microstructure of the alloy was examined with optical microscopy while its mechanical properties were determined by the tensile and Brinell hardness tests. The friction and wear tests were carried out using a ball-on-disc type tribometer. These tests were performed at constant sliding speed and distance under different load. Worn surface of the alloy, ball surface and wear debris were examined with SEM-EDS. Results: Multi-directional hot forging resulted in both breaking up the silicon particles and elimination of dendritic structure of the alloy. This process increased the yield and tensile strength with percentage elongation of the alloy but decreased its hardness. The highest yield and tensile strength were obtained from the alloy forged two cycles, while the alloy forged three cycles showed a lowest hardness but highest percentage elongation. On the other hand, the alloy hot forged states exhibited the higher friction coefficient and lower wear resistance than that of its homogenized state. After the wear test, smeared and delaminated layer were observed on the worn surface of the alloy in all test conditions. Conclusions: The main conclusions of this study were summarized as: The multi-directional hot forging resulted in the breaking up the silicon particles and the elimination of the dendritic structure. The multi-directional hot forging gave rise to an increase in the strength and ductility of the Al-7Si-4Zn-3Cu alloy. The multi-directional hot forging caused to an increase in friction coefficient and mass loss of the tested alloy. The friction coefficient of the alloy decreased as the load increased but its mass loss exhibited a reverse trend. Smearing and delamination were observed to be effective wear mechanisms of the alloy in all states.