Mg , Si and die geometry effects on the formability and the machinability of recycled aluminium alloys
Mg, Si and die geometry effects on the formability and machinability were experimentally reported, concerning AA6xxx aluminium alloys which were produced by recycling raw material. The aluminium alloys formability characteristics were evaluated during extrusion and open die forging tests estimating the needed load; the machinability characteristics of the same aluminium alloys were conducted via cutting force measurements during simple turning process. Key-Words: formability, machinability, Mg ratio, Si ratio, extrusion test, cutting, recycling
Simulation of the precision forging of bevel gears using implicit and explicit FE techniques
Abstract The implicit FE code MARC has been used to simulate the precision forging of a bevel gear. The true coupled thermomechanical forming conditions have been adopted to describe the metal flow during the process and the results obtained have been validated by extensive experimental work. An attempt has been made also to use a time-consuming explicit FE code, DYNA 3D; however, limitations were apparent in simulating the total procedure due to structural restrictions of this code. A CAD/CAM/CAE system able to successfully analyse such a precision forging operation is on hand.
Effect of preheat time–temperature cycles on development of microstructure and properties of extrusions prepared from Al–Fe–Mn rapidly solidified povvders
AbstractThe transformation of rapidly solidified structures during preheating and extrusion has been investigated by using X-ray techniques and transmission electron microscopy. It was found that the rapidly solidified phases are generally unstable at processing temperatures and transform to equilibrium phases upon exposure to temperatures greater than 400°C. Transformation is an order of magnitude faster under the influence of stress during an extrusion cycle. The effect of increasing compact preheat time leads to substantial coarsening of the microstructure, which has an adverse effect on the mechanical properties. The effect of preheat time–temperature cycles has been investigated by comparing the microstructure and mechanical properties of extrudates produced from induction heated compacts (preheat time 4–5 min) and air heated compacts (preheat time 75 min).Significant property improvements are obtained in extrudates produced from rapidly heated compacts. The results indicate that the properties vary ...