Grain-Oriented Electrical Steel Sheet Manufacturing Texture Control
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Solution Overview
Problem
Conventional methods for manufacturing grain-oriented electrical steel sheets face challenges in controlling the texture of primary recrystallized sheets and effectively utilizing inhibitors, leading to suboptimal magnetic properties due to fine crystal grains formed during hot-rolled sheet annealing, which inhibit grain growth and reduce the frequency of Goss-oriented grains.
Innovation Solution
A method involving coarsening crystal grains before cold rolling, optimizing rough rolling conditions to increase low-strain crystal grains, and adjusting hot-rolled sheet annealing temperatures based on recrystallization ratios to create a suitable primary recrystallized texture, while actively utilizing inhibitors to achieve high magnetic flux density through secondary recrystallization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If slab heating temperature is increased to 1300°C or higher to solubilize inhibitors, then inhibitor fine precipitation is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the inhibitor solubilization step from the slab heating process and relocates it to the hot-rolled sheet annealing stage. By taking out the high-temperature heating requirement from the initial slab heating and performing it later at a more economical stage, the patent achieves fine inhibitor precipitation without the need for expensive 1300°C+ slab heating.
Solution Approach 2:
The patent employs a more economical heating approach by using hot-rolled sheet annealing (a shorter, lower-cost thermal process) instead of extended high-temperature slab heating. This disposable-like approach uses a targeted, short-duration thermal treatment at the optimal stage to achieve inhibitor precipitation without the continuous high-energy input of traditional slab heating.
2Manufacturing precision
If crystal grain size before cold rolling is increased to improve Goss orientation, then magnetic flux density is improved, but texture control difficulty increases
Solution Approach 1:
The patent applies preliminary action by establishing the desired crystal grain structure through high-temperature rough rolling before cold rolling. This preliminary texture formation creates a robust grain structure that is less sensitive to subsequent processing variations, thereby improving magnetic flux density while simplifying overall texture control.
Solution Approach 2:
The patent uses parameter changes by controlling the finishing temperature to 950°C or higher to suppress inhibitor precipitation at this stage. This temperature parameter control allows larger crystal grains to form before cold rolling, improving Goss orientation and magnetic flux density, while the inhibitors still form later during hot-rolled sheet annealing to provide necessary grain boundary control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in grain-oriented electrical steel sheets with excellent magnetic properties, achieving a magnetic flux density of 1.935 T or higher by strictly controlling the texture and inhibitor distribution, enhancing energy efficiency and reducing transformer noise.
Implementation Method 1
subjecting the steel slab to slab heating to a temperature of higher than a γ-phase precipitation temperature and 1380° C. or lower
Implementation Method 2
subjecting the hot-rolled sheet to hot-rolled sheet annealing for soaking at a soaking temperature of 1000° C. or higher and (1150-2.5Y)° C. or lower
Implementation Method 3
subjecting the steel slab to slab heating to a temperature of higher than a γ-phase precipitation temperature
Implementation Method 4
rough rolling including at least two passes of rolling at a temperature of (temperature at which γ-phase fraction reaches its maximum −20° C.) or higher
Data Source
AI summary
The method includes slab-heating a steel slab to a temperature of higher than a γ-phase precipitation temperature and 1380° C. or lower, subjecting the steel slab to rough rolling including at least two passes of rolling at a predetermined temperature with an introduced sheet thickness true strain εt of 0.50 or more and to finish rolling with a rolling finish temperature of 900° C. or higher to obtain a hot-rolled sheet, cooling the hot-rolled sheet for 1 second or longer at a cooling rate of 70° C./s or higher within 2 seconds after finish rolling, coiling the sheet at a coiling temperature of 600° C. or lower, performing hot-rolled sheet annealing for soaking at a predetermined soaking temperature, and then performing cold rolling, primary recrystallization annealing, and secondary recrystallization annealing.