An investigation on thermo-mechanical and microstructural issues in friction surfacing of Al–Cu aluminum alloys

In this study, the thermo-mechanical behavior and microstructural transformations of AA2024 during the friction surfacing process have been investigated.A three-dimensional finite element model has been developed to predict the thermo-mechanical responses of materials during friction surfacing using the ABAQUS software.Then, the mechanical properties and microstructures of the coating layer were evaluated.The results show that the temperature of the advancing side of the coating increases more than that of the retreating side, which is consistent with the coating's tendency to deviate towards this side.The strain rate is also higher and more extended on the advancing side, which is the main reason for weaker coating bonds in this area than on the retreating side.The strain rate and maximum temperature in the coating layer increase with increasing the consumable rod rotational speed and the axial feeding rate, but an increase in the traverse speed increases the strain rate and reduces the maximum temperature.Although the material transfer process is asymmetrical, there are not any significant differences observed in the material microstructure and properties on the advancing and retreating sides.The cooling rate appears to be the most effective factor on the coating grain size at the coating/substrate interface.Higher cooling rates results in the formation of finer grains at the interface.It can be noted that the effect of strain energy stored in the coating layer during friction surfacing on the grain structure evolution and the interface bonding strength is negligible.Therefore, heat flow was found out to be the prominent factor in the coating grain size and strength.