A PROCESS MODEL FOR FRICTION WELDING OF AL-MG-SI ALLOYS AND AL-SIC METAL-MATRIX COMPOSITES .2. HAZ MICROSTRUCTURE AND STRENGTH EVOLUTION

The present investigation is concerned with the development of an over all process model for the microstructure and strength evolution during continuous drive friction welding of Al-Mg-Si alloys and Al-SiC metal matrix composites. In Part II the heat and material flow models prese nted in the first paper (Part I) are utilized for prediction of the HA Z subgrain structure and strength evolution following welding and subs equent natural ageing. The modelling is done on the basis of well esta blished principles from thermodynamics, kinetic theory and simple disl ocation mechanics. The models are validated by comparison with experim ental data, and are illustrated by means of novel mechanism maps. Thes e show the competition between the different process variables that co ntribute to microstructural changes and strength losses during frictio n welding of Al-Mg-Si alloys and Al-SiC metal matrix composites.