Effect of the Initial Texture, Recrystallization and Re-Dissolution Process on the Evolution of Texture during Solution Treatment of the 7A65 Hot Rolled Plate

The evolution of textures, the degree of recrystallization and the mechanical properties of 7A65 hot rolled plates during re-dissolution were studied with different thicknesses (25 mm, 65 mm, 120 mm) and different degrees of deformation. It was found that different plates exhibited different trends of re-dissolution because the degrees of deformation increased and the degrees of recrystallization were different during the solution treatment. With the increase of deformation and static recrystallization degrees, texture types changed from Cube, R-Cube to Brass, R, Cube and Copper during the re-dissolution process. The value of the Schmid factor (µ¯) was calculated and the value along the rolling direction was significantly larger than along the transverse direction, which led to a lower yield strength along the rolling direction. In terms of the average contribution of the yield strength, the strengthening of the grain boundary including LAGBs (low-angle grain boundaries) was found to play a more significant role than the effect of solid atoms and dislocation densities. Therefore, the 25 mm plate exhibits the best mechanical properties, with a yield strength of 565.7 MPa along the rolling direction

Effect of the Initial Texture, Recrystallization and Re-Dissolution Process on the Evolution of Texture during Solution Treatment of the 7A65 Hot Rolled Plate

The evolution of textures, the degree of recrystallization and the mechanical properties of 7A65 hot rolled plates during re-dissolution were studied with different thicknesses (25 mm, 65 mm, 120 mm) and different degrees of deformation. It was found that different plates exhibited different trends of re-dissolution because the degrees of deformation increased and the degrees of recrystallization were different during the solution treatment. With the increase of deformation and static recrystallization degrees, texture types changed from Cube, R-Cube to Brass, R, Cube and Copper during the re-dissolution process. The value of the Schmid factor (µ¯) was calculated and the value along the rolling direction was significantly larger than along the transverse direction, which led to a lower yield strength along the rolling direction. In terms of the average contribution of the yield strength, the strengthening of the grain boundary including LAGBs (low-angle grain boundaries) was found to play a more significant role than the effect of solid atoms and dislocation densities. Therefore, the 25 mm plate exhibits the best mechanical properties, with a yield strength of 565.7 MPa along the rolling direction

Strengthening effects of GP zone induced by SiCp size variations in Al–Si–Mg matrix composites

In this work, SiCp reinforced Al–Si–Mg matrix composites were prepared by stirring casting with different SiCp sizes. The effect of SiCp sizes on the microstructure and mechanical properties was investigated, and different strengthening effects were systematically calculated and analyzed. With the decrease of SiCp sizes, the microstructure of composites is refined and the plasticity is improved significantly. The refined SiCp also leads to a more intense grain refinement strengthening and thermal expansion mismatch strengthening. However, an abnormal decrease of yield strength is discovered with the refinement of SiCp, which is due to the influence of SiCp on GP zones strengthening in the matrix. As SiCp sizes decreasing, the increased SiCp/Al interfaces capture more Mg atoms, and then inhibits the formation of GP zones in the α-Al. Therefore, the refined SiCp weaken the precipitation strengthening in composites. These acicular Mg–Si GP zones exhibit a preferentially growing direction along Al and present a same structure as α-Al with coherent interfaces which pin dislocations and provide precipitation strengthening. The high density of GP zones also increases nano-hardness and elastic modulus of α-Al, which improves the wear resistance of SiCp/Al–Si–Mg composites. Therefore, it is suggested that the interaction between the SiCp and precipitates in matrix should also be considered to obtain a suitable strengthening effect in the design of SiCp/Al alloy composites