Effects of Dies Exit Temperature on Microstructure and Mechanical Properties of Extruded

초록

Aluminum extrusion is widely used to manufacture metal part and component for automobile and electrical products. In general, temperature of extruded aluminum is higher than that of billet because heat compensation occurs during extrusion. Hence, it is very important to maintain a constant temperature of extruded aluminum in order to guarantee uniform microstructure and mechanical properties of extruded profile during the entire extrusion period. However, it is difficult to maintain a constant exit temperature owing to the increase of die temperature resulted from friction between bearing part and billet material in continuous extrusion process. Therefore, dies cooling system is often used to maintain bearing temperature of dies. Without dies cooling system, both reducing ram speed or changing dies would be also one way to suppress an increase of dies exit temperature. In this case, the effects of dies exit temperature on microstructure and mechanical properties of extruded aluminum has to be evaluated in order to control the release of cooling matters such as nitrogen or water. In this study, therefore, we have tried to investigate a changing of microstructure and mechanical properties according to exit temperature using aluminum 7021 alloy.