Microstructure and texture evolution during the ultra grain refinement of the Armco iron deformed by accumulative roll bonding (ARB)

The Armco iron is one of the purest commercial iron with very low levels of carbon, oxygen and nitrogen. In order to improve the mechanical properties, it is worth applying severe plastic deformation to obtain ultrafine-grained bulk materials, with grain size <1 μm. In this study, samples of Armco iron were subjected to a technique of severe plastic deformation named Accumulative Roll Bonding. The important parameter of this process is the number of passes and the deduced von Mises equivalent strain. ns of the Electron BackScattered Diffraction and X-Ray diffraction, the evolution of microstructure and texture with the applied strain was studied. The microhardness was also measured as a function of the equivalent strain and reached 280 HV after 7 ARB cycles. The ARB technique applied to Armco iron resulted in a microstructure of ultrafine grains of about 580 nm after 7 cycles, with a high angle grain boundary fraction of 60%. The texture is mainly composed of α and γ fibers with a reinforcement of both {001}〈110〉 and {111}〈110〉 components.