Influence of dynamic recrystallization mechanisms on the texture evolution of GH4706 alloy during hot deformation

Abstract

In this study, the hot deformation behavior and microstructural evolution of the GH4706 alloy under various thermal processing parameters (TPPs) were investigated through hot deformation experiments and electron backscatter diffraction (EBSD) microstructural characterization. The findings suggest that increasing hot compression temperature (T) and reducing strain rate (ε̇) enhance the degree of dynamic recrystallization (DRX), significantly reducing flow stress and weakening texture intensity. Increasing strain (ε) promotes DRX, with the overall texture strength initially increasing before decreasing. During hot compression at 1000 −1100 ℃, discontinuous dynamic recrystallization (DDRX), continuous dynamic recrystallization (CDRX), and twin-induced dynamic recrystallization (TDRX) jointly influence texture development. Among these, DDRX plays a dominant role, with numerous DDRX grains exhibiting dispersed orientations, significantly contributing to texture weakening. The CDRX mechanism induces a limited number of randomly oriented grains within the deformed grains, and its contribution to texture weakening is enhanced with increasing ε and decreasing T. The TDRX mechanism generates DRX grains within Σ3 twin boundaries deviating from their theoretical orientation, and these grains inherit the twin orientation, exerting a limited effect on texture weakening. These findings provide a theoretical foundation for a deeper understanding of DRX behavior and texture evolution in the GH4706 during hot working.

1. Introduction

Nickel-based superalloys exhibit remarkable structural stability, hot corrosion resistance, and mechanical properties at temperatures above 600 ℃, making them essential materials for the manufacturing of hot-end components [1−3]. These alloys are widely used in aerospace engines and gas turbines. With the rapid advancement of technology, the operating environments of aerospace engines have become increasingly harsh, imposing more stringent performance demands [4, 5]. GH4706 alloy, a deformation-resistant superalloy, can endure operating temperatures up to 650 ℃ after being formed through die forging, and it demonstrates excellent yield strength, creep resistance, and fatigue performance [6−8]. These characteristics are primarily attributed to the microstructural evolution under thermal processing parameters (TPPs). The key factors influencing the final product performance are the texture evolution and maximum pole density [9−11]. AMIR et al [12] investigated the formation of recrystallized rotated cube texture contributing to a reduction in overall texture strength, decreasing in-plane anisotropy from 11.6% to 2.4%. WANG et al [13] demonstrated that the {001} <110> texture formed during cross-rolling enhances strength in both the rolling and transverse directions. GUO et al [14] demonstrated that the {111}<112> and {111}<110> textures, which form after low-temperature (T) deformation and aging, improve the electrical conductivity of the material.

Furthermore, it is important to note that the formation and evolution of textures such as Goss {110} <100> and rotated cube {001} <110> are dependent on the degree of dynamic recrystallization (DRX) [15]. Therefore, DRX behavior is closely linked to the development of texture [16−19]. Under different TPPs, most recrystallized grains formed during hot working tend to exhibit random orientations [20, 21]. However, the effect of the DRX mechanism on texture weakening in nickel-based superalloys remains unclear.