Investigation of Primary Recrystallization and Decarbonization with Different Heating Rates of Intermediate Annealing Using Nb-Containing Grain-Oriented Silicon Steel

Xin Tian,Jie Li,Yunli Feng,Shuang Kuang,Jing Guo

doi:10.3390/met11101655

Abstract

An Nb-containing grain-oriented silicon steel was produced through double-stage cold rolling in order to investigate the effect of the heating rate during intermediate annealing on primary recrystallization and decarburization behavior. The microstructure and texture were observed and analyzed by an optical microscope and an electron backscatter diffraction system. A transmission electron microscope was used to observe the precipitation behavior of inhibitors. The decarburization effect during intermediate annealing was also calculated and discussed. The results show that primary recrystallization takes place after intermediate annealing. As the heating rate increases, the average grain size decreases gradually. The textures of {411}<148> and {111}<112> were found to be the strongest along the thickness direction in all of the annealed specimens and are mainly surrounded by HEGB and HAGB (> 45°). A large number of inhibitors with the size of 14~20 nm precipitate are distributed evenly in the matrix. The above results indicate that the higher heating rate during intermediate annealing contributes to both an excellent microstructure and magnetic properties. From the calculation, as the heating rate increases, decarbonization tends to proceed in the insulation stage, and the total amount of carbonization declines.

Highlights

Grain-oriented silicon steel, which is mainly used as the core material of transformers, is the only product manufactured through a secondary recrystallization process in the steel [1]
In order to investigate the effect of different different heating heating rates rates during during the the intermediate intermediate annealing process, the recrystallized microstructure, texture, grain boundary characteristics process, the recrystallized microstructure, texture, grain boundary and inhibitors are characteristics anddiscussed inhibitorsbelow
When the heating rate is within 10~25 ◦ C/s, the differences in rate is rate is 30

Summary

Introduction

Accepted: 15 October 2021Grain-oriented silicon steel, which is mainly used as the core material of transformers, is the only product manufactured through a secondary recrystallization process in the steel [1]. The key technology used to produce grain-oriented silicon steel with the sharp Goss texture is effective control of the inhibitors [3,4,5]. It is imperative to develop new types of inhibitors to realize slab reheating with a low temperature. The researchers in this study turned their focus to Cu sulfides, which mainly exist in the form of compounds, related reports do not express a consistent viewpoint about their specific types and precipitation mechanisms [10,11,12]. Taking Cu sulfides as the main inhibitor, the slab temperature of grain-oriented silicon steel still needs to be reheated to above 1250 ◦ C [13]. Niobium carbide/nitride is found to have a number of similar features to common inhibitors, Published: 19 October 2021

Results

Discussion

Conclusion