Modeling Dynamic Recrystallization Behavior in a Novel HIPed P/M Superalloy during High-Temperature Deformation

Understanding microstructural evolution during hot deformation is critical for optimizing superalloy processing. Prior research has shown that deformation parameters influence grain growth and dynamic recrystallization (DRX). However, the specific interactions between temperature, strain rate, and DRX in HIPed powder metallurgy superalloys remain unclear. This uncertainty drives the need for predictive models. Existing models often fail to capture the piecewise nature of DRX behavior across varying conditions. No prior work had resolved the full range of DRX responses in this specific alloy system. The lack of detailed microstructure-deformation correlations limits practical applications. This gap motivated the current investigation into DRX mechanisms and modeling. The study aims to bridge theoretical predictions with real-world deformation outcomes.

The study aims to analyze how deformation parameters affect DRX and grain growth in a novel HIPed P/M superalloy. The specific problem is the lack of accurate predictive models for microstructure evolution under hot deformation. The motivation is to enable better control of material properties during manufacturing. The goal is to establish reliable mathematical models for DRX behavior and grain growth. These models can guide hot forming processes for superalloy parts. The study also seeks to validate these models through simulation and experimentation. The focus is on capturing the piecewise nature of DRX kinetics. The ultimate purpose is to improve the practical application of P/M superalloys.

Hot-compression tests were conducted to observe DRX and grain evolution in the superalloy. The sensitivity of grain size and DRX to deformation parameters was analyzed. Deformation conditions included variations in temperature, strain rate, and true strain. The DRX process was studied under different thermal and mechanical settings. Mathematical models were developed to predict DRX behavior and grain growth. Piecewise DRX kinetics equations were proposed based on test results. The grain-growth model was integrated into DEFORM software for simulation. Simulated DRX features were compared with experimental data to validate accuracy.

DRX features and grain growth were strongly influenced by deformation parameters. Higher temperatures and strains promoted DRX but also accelerated grain growth. At strain rates of 0.1 s⁻¹ and 1 s⁻¹, uniform microstructures with small grains were observed. The DRX rate varied significantly with temperature, necessitating piecewise equations. The proposed DRX kinetics equations accurately predicted DRX behavior across conditions. The grain-growth model effectively described microstructure evolution. Simulations using DEFORM matched experimental results closely. The models provide a reliable basis for hot forming of P/M superalloys.

The study confirms that DRX and grain growth in HIPed P/M superalloys depend on deformation parameters. The proposed piecewise DRX kinetics equations capture the behavior accurately. The grain-growth model successfully predicts microstructure evolution. Simulations validated the models' reliability across various conditions. The findings suggest that these models can guide hot forming processes effectively. The results support practical applications in superalloy manufacturing. The models offer a useful tool for optimizing deformation parameters. The study highlights the importance of integrating simulation with experimental data.