Grain-Oriented Electrical Steel Sheet Manufacturing Process
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Solution Overview
Problem
Existing methods for manufacturing grain-oriented electrical steel sheets struggle to effectively improve magnetic flux density, despite efforts to control crystal grain orientation and inhibit unwanted grain growth.
Innovation Solution
The method involves setting the finish rolling temperature to 950°C or below, initiating cooling within 2 seconds post-finish rolling, and maintaining a coiling temperature of 700°C or below, along with a heating rate of 5°C/sec or higher during annealing, to refine recrystallized grains and enhance {110} orientation integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional nitriding methods are used to control crystal grain orientation, then inhibitor deposition is achieved, but magnetic flux density improvement is insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling finish rolling temperature (950°C or below), cooling rate (13-14°C/sec), and coiling temperature (700°C or below) to suppress unwanted recrystallization and grain growth before annealing, thereby improving magnetic flux density beyond conventional methods
2Manufacturing precision
If finish rolling temperature is reduced to suppress grain growth, then crystal orientation control is improved, but productivity decreases due to extended cooling time
Solution Approach 1:
The patent implements periodic action through rapid cooling (13-14°C/sec) immediately after finish rolling, creating a controlled thermal cycle that suppresses grain growth during cooling while enabling subsequent efficient annealing processing
Solution Approach 2:
The patent applies preliminary action by performing controlled cooling and coiling at specific temperatures before the annealing process, preparing the steel strip in advance to suppress unwanted grain growth and recrystallization, thereby improving final crystal orientation without extending overall production time
3Manufacturing precision
If rapid cooling is applied after finish rolling to suppress recrystallization, then grain structure control is improved, but temperature control difficulty increases
Solution Approach 1:
The patent applies dynamics by implementing a specific cooling rate (13-14°C/sec) that dynamically controls the thermal process after finish rolling, enabling precise suppression of recrystallization and grain growth while maintaining manageable temperature control through defined parameters
4Reliability
If heating rate during annealing is increased to refine recrystallized grains, then magnetic characteristics improve, but energy consumption increases
Solution Approach 1:
The patent applies parameter changes by setting the heating rate during annealing to 5°C/sec or higher within the temperature range of 800-1000°C, which refines recrystallized grains and improves magnetic characteristics while managing energy consumption through controlled parameter ranges
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 significantly increases magnetic flux density and reduces iron loss by promoting a structure conducive to Goss orientation through controlled recrystallization processes.
Implementation Method 1
hot rolling the heated silicon steel slab
Implementation Method 2
annealing the hot-rolled steel strip
Implementation Method 3
recrystallization and grain growth before annealing may be suppressed
Implementation Method 4
decarburization annealing the cold-rolled steel strip so as to obtain a decarburization-annealed steel strip in which primary recrystallization is caused
Implementation Method 5
performing a nitriding treatment in which a N content of the decarburization-annealed steel strip is increased
Implementation Method 6
finish annealing the decarburization-annealed steel strip so as to cause secondary recrystallization
Data Source
Figure 1
Figure 2~3
AI summary
In a method of manufacturing a grain-oriented electrical steel sheet including a nitriding treatment (step S7) and adopting so-called "low-temperature slab heating", the finish temperature of finish rolling in hot rolling (step S2) is set to 950°C or below, the cooling is started within 2 seconds after completion of the finish rolling, and a steel strip is coiled at 700°C or below. The cooling rate over the duration from the end of finish rolling to the start of coiling is set to 10°C/sec or above. In annealing (step S3) of the hot-rolled steel strip, the heating rate in the temperature range from 800°C to 1000°C is set to 5°C/sec or above.