Recovery and Recrystallization Behaviors of Ni\u201330 Mass Pct Fe Alloy During Uniaxial Cold and Hot Compression

Itsuki Yamaguchi,Mitsuharu Yonemura

doi:10.1007/s11661-021-06323-4

Abstract

The recovery and recrystallization behaviors of the high-temperature γ-phase of carbon steel during deformation strongly affect the mechanical properties of steel. However, it is difficult to evaluate such behaviors at a high temperature. This study proposes the deformation behavior of the high-temperature γ-phase of low-carbon steel based on the quantitative observation of dislocation density and vacancies in the Ni–30 mass pct Fe alloy. This alloy was used because its stacking fault energy (60 to 70 mJ m-2) is similar to that of low-carbon steel. Uniaxial compression tests were conducted at a strain rate of 10−3 s−1 and 1473 K (1200 °C) for dynamic recrystallization and at 293 K (20 °C) for work hardening. The compression process was interrupted at different strain values to systematically investigate microstructural changes. The changes in work hardening, recovery, and recrystallization behaviors were obtained from the true stress–true strain curves of the uniaxial compression tests. Further, the microstructure changes during cold and hot uniaxial compression were investigated from the viewpoint of lattice defects by X-ray diffraction, positron annihilation analysis, transmission electron microscopy, and electron backscatter diffraction to comprehend the work hardening, dynamic recovery (DRV), and dynamic recrystallization (DRX). This study helps understand the DRV, DRX, and work hardening behaviors in the γ-phase of the Ni–30 mass pct Fe alloy during cold and hot compression.

Highlights

STEEL is typically produced by the thermomechanical control process with precise control of the reduction rate and heat treatment temperature to form microstructures that improve its mechanical properties
The decrease in true stress after reaching maximum true stress is consistent with the decrease in the true stress of the specimens, which results after the interruption at each strain indicated by the arrows
True stress reaches its maximum value at e = 0.065 and decreases. This behavior is presumed to indicate the initiation of DRX, i.e., the specimen softens owing to the formation of dislocation-free dynamically recrystallized grains

Summary

Introduction

STEEL is typically produced by the thermomechanical control process with precise control of the reduction rate and heat treatment temperature to form microstructures that improve its mechanical properties. Significant research has been done on grain refinement by static recovery and recrystallization during heat treatment to improve the strength and elongation in low-carbon steel.[1,2,3] the coarsening of grains is used for controlling the distribution of crystal orientation (i.e., the crystallographic texture) for electromagnetic steel. In addition to the static recovery and recrystallization by cold working and heat treatment, dynamic recovery (DRV) and dynamic recrystallization (DRX) have been observed in steel materials during large-strain deformation processing.[4,5,6] Currently, DRX is an important phenomenon for grain refinement.

Methods

Results

Discussion

Conclusion