Microstructure and surface of 2A12 aluminum alloy cladded with pure aluminum after solution treatment

Abstract

The effects of solution temperature and holding time on the microstructure, mechanical properties and surface morphology of 2A12 aluminum alloy sheets were discussed in this paper. The universal tensile tester was used to test the tensile strength and yield strength of aluminum alloy sheets with different treatment systems. The surface morphology of the alloy sheets was characterized by a white light interference profile scanner, and the microstructure of the sheets was characterized by optical microscope (OM), scanning electron microscope (SEM) and electron backscattered diffraction (EBSD). The results showed that the mechanical properties of the sheets could not satisfy GBT228.1-2010 national standard when the holding time was 10 min and the holding temperature was 475 °C. However, under the other heat treatment systems, the alloy could reach the GBT228.1-2010 national standard. Moreover, with the extension of the holding time, the part of the matrix gradually diffused into the aluminum-clad layer. When the holding time was shorter than 25 min, the boundary between the matrix and the aluminum-clad layer was relatively obvious. And the diffusion gradually became obvious when the holding time was over 25 min. Thereby, the boundary became blurry. The further investigation suggested that the solution temperature of 495 °C and the holding time of 35 min showed better mechanical properties and better surface morphology.