Grain-Oriented Electrical Steel Rapid Cooling for Magnetic Texture
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Solution Overview
Problem
Existing methods for producing grain-oriented electrical steel sheets do not effectively utilize rapid cooling techniques to enhance magnetic properties, which are crucial for high-performance transformers and generators.
Innovation Solution
The method involves increasing the cooling rate during hot-band annealing and intermediate annealing from 800°C to 300°C to not less than 200°C/s, which changes the slip system of dislocations during cold rolling, improving primary recrystallization texture and magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cooling rates (less than 100°C/s) are used in hot-band annealing, then the production process is simpler and equipment requirements are lower, but the magnetic properties of the steel sheet are insufficient
Solution Approach 1:
The patent changes the cooling rate parameter from conventional less than 100°C/s to a higher range of 100-500°C/s during hot-band annealing. This parameter change transforms the cooling process to achieve superior magnetic properties (B8 ≥ 1.93 T) without requiring complex equipment, as the patent uses a conventional continuous annealing installation with a quench-hardening device.
Solution Approach 2:
The patent applies preliminary rapid cooling during hot-band annealing to control carbide precipitation and create a specific microstructure before cold rolling. This preliminary action of rapid cooling modifies the steel sheet structure in advance, preparing it for subsequent processing and ensuring excellent magnetic properties in the final product.
2Manufacturing precision
If rapid cooling rate of not less than 100°C/s is applied in hot-band annealing, then the magnetic properties are significantly improved, but conventional cooling devices cannot achieve the required cooling rate
Solution Approach 1:
The patent makes the conventional quench-hardening device, originally designed for producing high-strength steel sheets, serve a new function by applying it to grain-oriented electrical steel sheet production. This multi-functional use allows the device to achieve rapid cooling rates of 100-500°C/s needed for excellent magnetic properties without requiring a specialized new cooling system.
Solution Approach 2:
The patent adjusts the cooling rate parameter to a specific range of 100-500°C/s that is achievable with existing quench-hardening equipment while still achieving the desired magnetic properties. This parameter optimization bridges the gap between equipment capabilities and performance requirements.
3Manufacturing precision
If high cooling rate is used to control carbide precipitation, then the primary recrystallization texture is improved, but the production efficiency may be reduced due to longer cooling time
Solution Approach 1:
The patent maintains continuous production by integrating the rapid cooling process into the existing continuous annealing line. The steel sheet undergoes continuous processing through hot-band annealing with rapid cooling, cold rolling, and subsequent annealing steps without interruption, ensuring both high manufacturing precision and sustained production efficiency.
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 a grain-oriented electrical steel sheet with significantly improved magnetic flux density, achieving excellent magnetic properties that are stable and industrially relevant.
Implementation Method 1
a method of improving a texture by increasing a cooling rate in a hot-band annealing and an intermediate annealing to control precipitation of carbide is proposed as a method for producing a grain-oriented electrical steel sheet having excellent magnetic properties. For example, Patent Literature 3 proposes increasing a cooling rate in a hot-band annealing to increase C in a solid-solution state in cold rolling.
Implementation Method 2
the cooling process is conducted from a maximum achieving temperature of 900 °C or higher at a cooling rate of 30-250 °C/s from 900 °C to 500 °C and a cooling rate of 50-150 °C/s from 500 °C to 200 °C
Implementation Method 3
The crystal structure is formed, in a finish annealing of the production process of the grain-oriented electrical steel sheet, by using grain boundary energy to preferentially cause secondary recrystallization of crystal grains of {110} orientation, so-called Goss orientation and achieve enormous growth thereof.
Data Source
AI summary
When a grain oriented electrical steel sheet is produced by heating a steel slab containing, by mass%, C: 0.02-0.10%, Si: 2.0-5.0%, Mn: 0.01-1.00%, sol. Al: 0.01-0.04%, N: 0.004-0.020% and S+Se: 0.002-0.040% to a temperature of higher than 1280°C, and subjecting the sheet to a hot rolling, a hot-band annealing, a single cold rolling or two or more cold rollings having an intermediate annealing between each cold rolling and a primary recrystallization annealing combined with a decarburization annealing, applying an annealing separator onto a steel sheet surface, and subjecting the sheet to a finish annealing and a flattening annealing, a rapid cooling is conducted at an average cooling rate of not less than 200°C/s from 800°C to 300°C in the cooling process from a maximum achieving temperature in at least one annealing of the hot-band annealing and the intermediate annealing, whereby a grain oriented electrical steel sheet having excellent magnetic properties is stably produced using a raw material containing an inhibitor-forming ingredient.