Flow Behavior Characteristics and Processing Map of Fe-6.5wt. %Si Alloys during Hot Compression

Shibo Wen,Feng Ye,Bao Zhang,Yongfeng Liang,Junpin Lin,Chaoyu Han

doi:10.3390/met8030186

Abstract

The flow behavior of Fe-6.5wt. %Si alloys during hot compression was investigated at temperatures 650–950 °C and strain rates 0.01–10 s−1. The results showed that the flow stress depended distinctly on the deformation temperatures and strain rates. The flow stress and work hardening rate increased with the decrease of temperature and the increase of strain rate. The activation energy under all the deformation conditions was calculated to be 410 kJ/mol. The constitutive equation with hyperbolic sine function and Zener–Hollomon parameter was developed. The peak stress, critical stress, and steady-state stress could be represented as σ = A + Bln(Z/A). Dynamic recrystallization occurred under the deformation conditions where the values of Z were lower than 1020. Processing maps were established to optimize the processing parameters. The power dissipation efficiency decreased in the high temperature and low strain rate region, increased in the high temperature and high strain rate region, and remained unchanged in other regions with the increase of true strain. Furthermore, the unstable area expanded. The true strain of 0.7 was the optimum reduction according to the processing map. Based on the analysis of surface quality, microstructures, and ordered structures, the optimized processing parameters for the Fe-6.5wt. %Si alloys were the temperature and strain rate of higher than 900 °C and 0.01–10 s−1, respectively, or 800–900 °C and lower than 0.4 s−1, respectively.

Highlights

Fe-6.5wt. %Si alloy has been considered as a potential material for application in high-frequency fields, such as transformers, power generators, and electric relays, as it is an excellent soft magnetic material with high electrical resistance, high relative permeability, nearly zero magnetostriction, low coercive force, and low iron loss [1,2,3]
650–950 ◦ C and strain rates ranging from 0.01–10 s−1
The flow behavior of the Fe-6.5wt. %Si alloy during hot compression was investigated at temperatures ranging from 650–950 °C and strain rates ranging from 0.01–10 s−1

Summary

Introduction

Fe-6.5wt. %Si alloy has been considered as a potential material for application in high-frequency fields, such as transformers, power generators, and electric relays, as it is an excellent soft magnetic material with high electrical resistance, high relative permeability, nearly zero magnetostriction, low coercive force, and low iron loss [1,2,3]. %Si alloy has been considered as a potential material for application in high-frequency fields, such as transformers, power generators, and electric relays, as it is an excellent soft magnetic material with high electrical resistance, high relative permeability, nearly zero magnetostriction, low coercive force, and low iron loss [1,2,3] Ordered structures such as B2 (Pm3m ) and. As indicated in previous reports, the rolling parameters, including temperature, rolling reduction, and strain rate, control the flow behavior [18] and microstructural evolution [19]. Other factors such as the degree of ordering [20] are important in the rolling process. These factors determine the deformation mechanisms of the alloy during the rolling process

Methods

Results

Conclusion