Hot deformation behavior and microstructure evolution of spray formed GH738 superalloy

Abstract

In order to evaluate the deformation characteristics of spray formed superalloy GH738, the hot compression test was conducted on Gleeble-3500 thermal mechanical simulator at a temperature range of 960 -1120 ºC, and a strain rates range of 0.1, 1.0 s -1 with engineering strain 50%. The flow stress data at various hot working conditions was obtained, and the influence of deformation temperature and strain rate on the microstructure evolution of spray formed GH738 was analyzed. The result shows that, the flow stress improves with the increasing of strain rate and the decreasing of temperature, the yield drop is observed on true stress-strain curves at strain rate of 1.0 s -1 . The temperature and strain rate have a strongly effect on dynamic recrystallization. Higher temperature could efficiently promote the process of dynamic recrystallization, as the increment of temperature, the dynamic recrystallization grain size shows the tendency of growth. Higher strain rate is better for grain refinement.

Constitutive Characteristic of Hot Deformation for Spray Formed Superalloy GH738

“…When the temperature was elevated, the increasing of atomic kinetic energy improves the coordination of the grains and eventually leads to the high-hot deformation ability. This phenomenon is in agreement with other investigations on superalloys [9][10][11].…”

Application of Taguchi method in optimizing the microstructure of 316LN austenitic stainless steel

“…And a number of numerical models and constitutive equations have been established to predict the flow stress under different deformation conditions. However, few investigators have paid attention to optimizing the process of hot deformation to refine the grain by using the dynamic recrystallization mechanism . It is noteworthy that the advantages of the hot deformation process optimization are not only to obtain a fine microstructure, but also to design accurately hot forging process.…”

Innovative technologies for powder metallurgy-based disk superalloys: Progress and proposal

“…[26] In recent years, most of the researches focusing on spray-forming, in conjunction with Cast & Wrought superalloys, have been already put into practice. [27][28][29][30][31][32][33][34][35] However, the work related to sprayforming of PM superalloys still lacks a rigorous and systematic approach. [36] Therefore, it becomes indispensable to further study spray-formed PM superalloys.…”