Grain-Oriented Electrical Steel Sheet Manufacturing
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Solution Overview
Problem
Current glassless technologies for manufacturing low core loss oriented electrical steel sheets face challenges in productivity due to difficulties in controlling oxidation capacity and dew point, leading to unstable secondary recrystallization and deviations in base coating formation, which hinder commercialization.
Innovation Solution
A manufacturing method involving hot-rolling, cold-rolling, primary recrystallization annealing, coating with an annealing separating agent, and secondary recrystallization annealing, where the dew points and temperature ranges are carefully controlled to form a specific oxidation layer and segregate a segregation layer, using magnesium oxide or hydroxide and metal iodide to remove the forsterite film, ensuring a stable surface and improved magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the oxidation capacity is controlled to be very low through hydrogen, nitrogen gas, and dew point change to suppress base coating layer formation, then the iron-based oxide production is suppressed and magnetism is improved, but the decarburization process must be longer to properly secure the decarburization characteristic, thereby productivity is deteriorated
Solution Approach 1:
The patent applies parameter changes by controlling the dew point within a specific range (50-70°C) and adjusting the oxidation capacity to an appropriate level rather than making it very low. This optimized parameter setting allows sufficient decarburization to occur within a normal processing time while still suppressing excessive base coating layer formation, thus resolving the contradiction between magnetic properties and productivity
Solution Approach 2:
The patent uses a composite approach by combining multiple elements (Si: 2-7%, Sn: 0.03-0.10%, Sb: 0.01-0.05%) in specific proportions to create a steel composition that achieves both adequate decarburization and controlled base coating formation. This composite material strategy allows the process to maintain both productivity and magnetic properties without requiring extended processing time
2Manufacturing precision
If the oxidation capacity is controlled to be very low to minimize the oxidation layer, then the base coating layer formation is suppressed, but it is difficult to secure an appropriate primary recrystallization grain size and secondary recrystallization grain growth occurs, causing productivity deterioration
Solution Approach 1:
The patent changes the oxidation capacity parameter from very low to an appropriate level (controlled through dew point of 50-70°C), which enables both proper base coating layer control and adequate primary recrystallization grain size development, thereby maintaining productivity while achieving manufacturing precision
3Reliability
If an ordinal pattern controlling the atmosphere and slowing the temperature raising rate is applied to suppress inhibitor diffusion, then secondary recrystallization stability is improved, but the processing time is extended
Solution Approach 1:
The patent applies parameter changes by optimizing the temperature raising rate and atmosphere composition rather than using a very slow rate. This allows the inhibitor to remain stable during heating while achieving secondary recrystallization in a reasonable time, thus resolving the contradiction between recrystallization stability and processing time
Solution Approach 2:
The patent uses a composite atmosphere composition (hydrogen, nitrogen, and ammonia in specific proportions) combined with optimized temperature control to achieve stable secondary recrystallization without requiring excessively slow heating rates, thereby maintaining both reliability and reasonable processing time
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 method enhances the stability of secondary recrystallization, improves magnetic domain mobility, and reduces core loss, while maintaining high productivity by controlling the oxidation layer thickness and composition, resulting in a metal gloss oriented electrical steel sheet with enhanced magnetic flux density and surface roughness.
Implementation Method 1
a step of decarburizing and nitriding the cold rolled sheet for primary recrystallization annealing
Implementation Method 2
a step of decarburizing and nitriding the cold rolled sheet for primary recrystallization annealing
Implementation Method 3
primary recrystallization annealing
Implementation Method 4
forsterite (Mg2SiO4), which is a base coating layer produced by a chemical reaction of a MgO slurry
Implementation Method 5
segregate a segregation layer
Data Source
AI summary
A manufacturing method of an oriented electrical steel sheet according to an exemplary embodiment of the present invention includes: a step of manufacturing a steel slab including one kind or more among Si at 2 to 7%, Sn at 0.03 to 0.10%, and Sb at 0.01 to 0.05% as wt %; a step of hot-rolling the steel slab to manufacture a hot rolled sheet; a step of cold-rolling the hot rolled sheet to manufacture a cold rolled sheet; a step of decarburizing and nitriding the cold rolled sheet for primary recrystallization annealing; a step of coating and drying an annealing separating agent on the primary recrystallization-annealed cold rolled sheet; and a step of secondary recrystallization-annealing the cold rolled sheet coated with the annealing separating agent.