Effect of Solution Treatment on Recrystallization,Texture and Mechanical Properties of 7A65-T74 Aluminum Alloy Super-thick Hot Rolled Plate

The effects of the solution treatment on the microstructure,recrystallization,texture composition and properties of 7A65-T7451(120 mm)hot rolled plates at H/2(1/2 thickness)and H/4(1/4 thickness)were studied.The results show that the hot rolled microstructure mainly contains a large amount of MgZn_(2) phases and minor Al_(7)Cu_(2)Fe phase.After solid solution treatments,a large amount of MgZn_(2) phases are dissolved back into the aluminum matrix.The main texture types at H/4 are R-Cube,Cube and part of Brass texture,and the main texture types at H/2 are Cube,R,and Copper texture.The qualitative analysis by Schmidt's law reveals that Copper texture at H/2 will deepen the anisotropy of plate metal properties.For the plate with the same thickness,the two-stage solution state has better mechanical properties due to the lower degree of recrystallization and stronger grain boundary strengthening effects.Under the two-stage solution system of 460℃/165 min+477℃/165 min,the composite mechanical properties of the alloy plate at H/4 are the best and the anisotropy is not obvious.The tensile strength,yield strength,and elongation along the rolling direction are 561.9 MPa,523.4 MPa,and 10.6%,respectively..

Improvement of microstructure and mechanical properties of Al−Cu−Li−Mg−Zn alloys through water-cooling centrifugal casting technique

The microstructure and mechanical properties of as-cast Al−Cu−Li−Mg−Zn alloys fabricated by conventional gravity casting and centrifugal casting techniques combined with rapid solidification were investigated.Experimental results demonstrated that compared with the gravity casting technique,the water-cooling centrifugal casting technique significantly reduces porosity,refinesα(Al)grains and secondary phases,modifies the morphology of secondary phases,and mitigates both macro-and micro-segregation.These improvements arise from the synergistic effects of the vigorous backflow,centrifugal field,vibration and rapid solidification.Porosity and coarse plate-like Al13Fe4/Al7Cu2Fe phase result in the fracture before the gravity-cast alloy reaches the yield point.The centrifugal-cast alloy,however,exhibits an ultra-high yield strength of 292.0 MPa and a moderate elongation of 6.1%.This high yield strength is attributed to solid solution strengthening(SSS)of 225.3 MPa,and grain boundary strengthening(GBS)of 35.7 MPa.Li contributes the most to SSS with a scaling factor of 7.9 MPa·wt.%^(-1).The elongation of the centrifugal-cast alloy can be effectively enhanced by reducing the porosity and segregation behavior,refining the microstructure and changing the morphology of secondary phases.