Grain-Oriented Electrical Steel Sheet Decarburization Annealing
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Solution Overview
Problem
The existing methods for manufacturing grain-oriented electrical steel sheets using low temperature slab heating face challenges in controlling the decarburization-annealed primary recrystallization grain structure, particularly due to limitations in heating rates and the need for multiple heating sources, which affects the stability and magnetic properties of the final product.
Innovation Solution
A method involving two-stage temperature range annealing of hot-rolled silicon steel sheets, where the decarburization annealing is conducted at a temperature range of 550°C to 720°C with a heating rate of at least 40°C/s, using induction heating to control lamella spacing and nitrogen content, ensuring the I{111}/I{411} ratio is maintained below 3, thereby stabilizing secondary recrystallization and improving magnetic flux density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If low temperature slab heating is used to manufacture grain-oriented electrical steel sheet, then energy consumption is reduced and equipment complexity is decreased, but the decarburization-annealed primary recrystallization grain structure becomes difficult to control
Solution Approach 1:
The patent applies parameter changes by precisely controlling the heating rate (at least 40°C/s in the 550-720°C range) and temperature ranges during decarburization annealing to achieve the desired I{111}/I{411} ratio below 3.0, thereby controlling the primary recrystallization grain structure despite using low temperature slab heating
Solution Approach 2:
The patent employs dynamic heating rate control, specifically increasing the heating rate to at least 40°C/s during the critical 550-720°C temperature range, to achieve stable secondary recrystallization and control the final grain structure while maintaining low overall processing temperature
2Speed
If multiple heating sources are used for decarburization annealing, then heating rate control is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical heating systems with induction heating technology, which uses electromagnetic fields to directly heat the steel sheet. This substitution achieves precise heating rate control (at least 40°C/s) while reducing equipment complexity and eliminating the need for multiple heating sources
Solution Approach 2:
The patent utilizes the controllable parameters of induction heating to achieve the required heating rate of at least 40°C/s in the 550-720°C range, demonstrating that a single modern heating source can replace multiple traditional heating sources while maintaining or improving control precision
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 allows for the stable production of grain-oriented electrical steel sheets with enhanced magnetic properties by controlling the grain structure and heating rate, enabling the use of induction heating exclusively and improving the manufacturing efficiency and product quality.
Implementation Method 1
heating in a temperature range of from 550°C to 720°C at a heating rate of at least 40°C/s
Data Source
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AI summary
In a production of grain-oriented electrical steel sheet that is heated at a temperature of not higher than 1350°C, (a) the hot-rolled sheet is heated to a prescribed temperature of 1000°C to 1150°C, and after recrystallization is annealed for a required time at a lower temperature of 850°C to 1100°C, or (b) in the hot-rolled sheet annealing process decarburization is conducted to adjust the difference in the amount of carbon before and after decarburization to 0.002 to 0.02 mass%. In the temperature elevation process used in the decarburization annealing of the steel sheet, heating is conducted in the temperature range of 550°C to 720°C at a heating rate of at least 40°C/s, preferably 75 to 125°C/s, utilizing induction heating for the rapid heating used in the temperature elevation process in decarburization annealing.