Grain-Oriented Electrical Steel Sheet Domain Refining for Lower Iron Loss
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Solution Overview
Problem
Existing grain-oriented electrical steel sheets face challenges in reducing iron loss and thermal shock while maintaining magnetic flux density and corrosion resistance, particularly due to limitations in current magnetic domain refining methods like etching, rolling, and laser techniques.
Innovation Solution
A combined approach using a permanent magnetic domain refining method and a temporary magnetic domain refining method, involving the formation of linear grooves and thermal shock portions on the steel sheet, with specific distance and energy density parameters for laser irradiation, to enhance magnetic domain refinement and minimize thermal shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a deep groove is formed to increase free charge area for permanent magnetic domain refining, then iron loss is reduced, but magnetic flux density deteriorates and thermal shock increases
Solution Approach 1:
The invention segments the groove formation into two distinct parts: a shallow groove formed by laser irradiation to provide magnetic domain refinement effect, and a thermal shock portion formed by subsequent thermal shock treatment to further refine domains without requiring deep groove penetration. This segmentation allows achieving sufficient magnetic domain refinement while maintaining magnetic flux density and reducing thermal shock compared to deep groove formation.
2Loss of energy
If a deep groove is formed to increase free charge area for permanent magnetic domain refining, then iron loss is reduced, but thermal shock increases
Solution Approach 1:
The groove is segmented into a shallow laser-formed portion and a thermal shock portion, where the thermal shock treatment is applied selectively to create domain refinement without requiring deep mechanical groove formation. This reduces the overall thermal shock to the steel sheet while achieving the necessary magnetic domain refinement for iron loss reduction.
Solution Approach 2:
Thermal shock treatment serves as an intermediary method to achieve magnetic domain refinement without directly forming deep grooves. The thermal shock portion acts as a mediator that provides the necessary domain refinement effect while minimizing the harmful thermal shock compared to deep groove formation and subsequent annealing processes.
3Loss of energy
If laser irradiation is applied with high intensity to form grooves for magnetic domain refining, then iron loss is reduced, but insulation coating is damaged
Solution Approach 1:
Instead of applying high-intensity laser irradiation to form deep grooves (excessive action), the invention uses partial action by forming only shallow grooves with controlled laser parameters. This partial groove formation is sufficient when combined with thermal shock treatment to achieve the necessary magnetic domain refinement while preserving the insulation coating and maintaining corrosion resistance.
4Loss of energy
If multiple processing steps are used for magnetic domain refining (etching, rolling, laser), then iron loss is reduced, but process complexity increases
Solution Approach 1:
The invention merges the groove formation process and thermal shock treatment into a single integrated process sequence. The laser forms shallow grooves and the thermal shock portion is created in the same processing cycle, combining what would traditionally require separate etching, rolling, and annealing steps into a more streamlined process that reduces overall process complexity while maintaining iron loss reduction effectiveness.
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
The combined method improves iron loss reduction and thermal shock resistance, maximizes corrosion resistance by minimizing damage to the insulation coating, and maintains magnetic flux density.
Implementation Method 1
a laser beam of high output is irradiated onto a surface portion of an electrical steel sheet moving at a high speed, and a groove accompanied by melting of a base portion is formed by the laser irradiation
Implementation Method 2
a linear thermal shock portion formed in the direction crossing the rolling direction on one surface or both surfaces of the electrical steel sheet
Data Source
AI summary
An embodiment of the present invention provides a grain-oriented electrical steel sheet, including: a linear groove formed in a direction crossing a rolling direction on one surface or both surfaces of an electrical steel sheet; and a linear thermal shock portion formed in the direction crossing the rolling direction on one surface or both surfaces of the electrical steel sheet. The groove is formed in plural along the rolling direction, a distance D2 between the groove and the thermal shock portion is 0.2 to 0.5 times a distance D1 between the grooves, and a distance D3 between the thermal shock portions is 0.2 to 3.0 times the distance D1 between the grooves.