The influences of radial-forward-backward extrusion on the microstructure and mechanical evolution of AM60 magnesium alloy by experimental and finite element micromechanical based cellular automaton approach

In this study the radial-forwad-backward extrusion of axially joint cup shaped AM60 magnesium alloy part is investigatd. In the experimental tests, the cylindrical AM60 alloy samples were prepaed and pressed by a punch into the die cavity. In the next step, the initial and extruded samples were investigated in terms of microstructural evolution and mechanical poperties variation. The microscopic observations showed the significant grain refinement of AM60 is occurred at the end of extrusion proessingwhere the fine grains in size of ~7μm are obtained from the initial value of ~75μm. Also, the Vickers microhardness is increased to 88Hv from the initial value of 56 Hv. The obtained results of uni-axial tensile tests showed the increase in yield and ultimate tensile strength to 142.6 and 290.3 from the initial value of 93 and 230MPa, respectively. The extruded sample elongation is incresead to 13.4% from 10% due to texture evolution, grain refinement and breakage of brittle eutectic phases. The macro and micromechancal based cellular automaton (CA) finite element method were implemented to simulate the process to predict the microstructure evolution of AM60 during extrusion processing. The cellular automaton finite element(CAFÉ) and experimentally obtained results were in good agreement. The effect of some important parameters including friction coefficient, gap thickness and height and die corner radius are studied on the variation of maximum forming load, microhardness values and grain size.