Grain Oriented Steel Sheet Laser Domain Refinement
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Solution Overview
Problem
Existing grain oriented electrical steel sheets fail to achieve sufficiently low iron loss values due to limitations in controlling crystal grains and reducing impurities, particularly with insufficient magnetic domain refinement effects from laser irradiation and titanium compound additions.
Innovation Solution
A grain oriented electrical steel sheet with suppressed nitrogen content in forsterite undercoating to 3.0 mass % or less, controlled aluminum and titanium content in forsterite undercoating, and uniform forsterite grain size, manufactured using specific steel smelting and annealing processes, including hot and cold rolling, decarburizing annealing, and laser irradiation for magnetic domain refinement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional laser irradiation techniques are used for magnetic domain refinement, then iron loss is reduced to some extent, but sufficiently low iron loss values cannot be achieved
Solution Approach 1:
The invention changes the chemical composition parameters of the forsterite undercoating, specifically suppressing nitrogen content to 3.0 mass % or less, and controlling aluminum content to 4.0 mass % or less and titanium content to 0.5-4.0 mass %. These parameter changes enhance the effectiveness of laser-induced magnetic domain refinement, enabling sufficiently low iron loss values to be achieved and meeting modern energy-saving requirements.
2Loss of energy
If aluminum and nitrogen contents are restricted in steel, then iron loss properties are improved, but the magnetic domain refinement effect by laser is insufficient
Solution Approach 1:
The invention applies local quality by creating non-uniform distribution of elements in the forsterite undercoating. Specifically, nitrogen is suppressed to 3.0 mass % or less, aluminum to 4.0 mass % or less, and titanium is controlled at 0.5-4.0 mass %. This localized compositional control in the undercoating layer enhances laser irradiation effectiveness for magnetic domain refinement while maintaining low iron loss properties.
3Loss of energy
If titanium compound is added to annealing separator, then iron loss is reduced, but the refinement effect is insufficient without proper nitrogen control
Solution Approach 1:
The invention uses a composite annealing separator containing magnesium oxide (100 parts by mass) and titanium compound (0.5 to 4 parts by mass in TiO2 conversion). This composite material approach, combined with suppressing nitrogen content in the forsterite undercoating to 3.0 mass % or less, creates synergistic effects that significantly enhance magnetic domain refinement by laser irradiation and achieve sufficiently low iron loss values.
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 solution significantly reduces iron loss, enabling the production of transformers with high energy consumption efficiency by achieving a magnetic flux density of at least 1.91 T, thereby meeting current energy-saving and environmental protection demands.
Implementation Method 1
irradiating a steel sheet as a finished product with laser to introduce linear, high-dislocation density regions into a surface layer of the steel sheet
Implementation Method 2
narrowing magnetic domain widths and reducing iron loss of the steel sheet
Implementation Method 3
subjecting the cold rolled steel sheet to decarburizing annealing
Implementation Method 4
employing an inert gas atmosphere not containing N2 as an annealing atmosphere in heating process of subsequent final annealing
Data Source
AI summary
A grain oriented electrical steel sheet is subjected to magnetic domain refinement by laser irradiation and has magnetic flux density B8 of at least 1.91T, wherein the nitrogen content in the forsterite coating is 3.0 mass % or less. The grain oriented electrical steel sheet satisfies recent demand for iron loss reduction.