Modelling and prediction of the yield strength of 6061 aluminum alloy processed by accumulative roll bonding (ARB)

In the present research, a quantitative approach was employed to investigate the mechanical properties of ultrafine grained 6061 aluminum alloy after different cycles of accumulative roll bonding (ARB) process. In this regard, the yield strength of samples was modelled based on the microstructural parameters extracted from x-ray diffraction (XRD) patterns and micrographs using corresponding mathematical equations. The microstructural features and mechanical properties of samples were analyzed by transmission electron microscopy (TEM) and uniaxial tensile test, respectively. The density of stored dislocations was calculated from XRD patterns by famous Williamson-Hall equation. Microstructural characterizations revealed that ultrafine grains as well as non-shearable precipitates were formed gradually by increasing the number of ARB cycles. The yield strength of ARBed samples was increased by increasing the number of cycles and reached to 278 MPa after third cycle. The grain refinement mechanism was the dominant strengthening mechanism in one cycle ARBed sample, contributing a strength increment estimated to about 95 MPa and its positive role was increased continuously by increasing the number of cycles. Also, the experimentally determined yield strength was in reasonable agreement with theoretically determined yield strength from strengthening mechanisms.