Research of rolling-drawing coupled deformation on the microstructure-property evolution and strengthening mechanism of 6201 conductive tubes

Abstract

To meet the major needs of national defense, transportation, aerospace, and other fields, aluminum alloys with excellent comprehensive performance are continually developed. To reduce the high cost of preparing high-performance aluminum alloys and alleviate the limitations of existing research, the effects of a rolling-drawing coupled deformation on the microstructure-property evolution and strengthening mechanism of 6201 conductive tubes developed by using two different processes were investigated. Subsequently, the evolution of grains, precipitates, texture, and dislocation were examined by performing optical microscopy, scanning electron microscopy, X-ray diffraction, and electron backscattered diffraction. The results showed that the main phases of the investigated tubes were the α-Al matrix, Mg2Si, and Al0.5Fe3Si0.5 second phase. The Al0.5Fe3Si0.5 phase with a face-centered cubic structure functioned as the inhomogeneous nucleation core of Mg2Si. In the rolling process, severe plastic-deformation-induced re-dissolution of the precipitated phases was observed, improving the effect of the subsequent solution treatment and aging treatment. An optimal ultimate tensile strength (UTS) of 341 MPa and electrical conductivity (EC) of 54.12% IACS were successfully obtained in the “extrusion-rolling-solution-aging-drawing” process. Compared with those of the initial tube, these values increased by 136.81% and 41.60%, respectively. However, after the order of rolling and solution treatments was reversed, the UTS and EC of the final tube decreased to 325 MPa and 52.91% IACS, respectively. The microstructure and performance evolution revealed that the uniformly distributed fine Mg2Si phase resulting from the good fit of the processes plays an important role in achieving a higher UTS and EC.