The Effect of Strain Rate on Abnormal Grain Growth of P/M Nickel-base Superalloy

The samples with a length of 50mm and cross section area of 20mm2 were machined from extruded P/M Nickel-base superalloy billet and the isothermal deformation tests were carried out at constant strain rate in a vacuum environment using the Thermecmastor. All the samples were deformed to a true strain of 1.04 at deformation temperature 1070 degrees C. and strain rate 0.001s-1 similar to 0.1s-1 respectively. The result is the deformation strain rate determine the position and domain of AGG. The aggregation of small grain boundary of all points has certain evolution for different strain rate and the AGG regions of all samples has relative higher grain boundary energy. The high percentage of low energy and low percentage of high migration of CSL boundaries may lead to AGG. The gradient and fluctuation of CSL boundaries in micro region may be comtribut the AGG.