The Effect Of Severe Cold Rolling And Post-deformation Annealing On The Microstructure And Mechanical Property

Grain refinement is an effective way to enhance the properties of one material.As one of way to refine the grain,the severe rolling can reduce the grain size and thus can be widely applied.In this research we fabricated nano-grain material via asymmetric and symmetric rolling.We examine the microstructure of nano-grain material by optical microscopy,transmission electron microscope,scanning electron microscope,XRD.We assessed the mechanical properties of materials based on the result of hardness and tensile test to find out the effect of severe cold rolling and post-deformation annealing on the microstructure and mechanical property of Ni based alloy GH80 A.In this work,we found that:(1)Nano-grained(NG)GH80A alloy with an average grain size about 50 nm was obtained through severe rolling at room temperature.The tensile strength increased a lot but the ductility decreased a lot.(2)After annealing,the recovery and recrystallization occurred and the second phase precipitated as well.So the strength increased at first and then fell with the increasing of annealing temperature but the ductility increased with the increasing of annealing temperature.(3)The cold rolled materials had higher UTS at 600? compared with the CG materials.But there was no difference in UTS at 700? between NG and CG materials.This was mainly because of the equicohesive temperature.