A study on the effect of cold rolling and annealing on special grain boundary fractions in commercial-purity nickel

It has been known for decades that thermomechanical processing, through cold working and annealing can effectively increase the fraction of special low energy grain boundaries in many FCC metals. The focus of the reported work was to study the effects of cold rolling and annealing processing parameters on both the fraction of special boundaries and the random boundary connectivity in commercially pure nickel. It was found that by using relatively low strain levels combined with high temperature anneals, it was possible to increase the fraction of special boundaries to 65% and severely fragment the random boundary connectivity.