Grain-Oriented Steel Sheet Stress Control for Lower Iron Loss
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Solution Overview
Problem
Conventional methods for reducing iron loss in grain-oriented electrical steel sheets by refining magnetic domain width are inadequate, as strain variations hinder the effectiveness of domain wall movement, leading to unsatisfactory iron loss reduction.
Innovation Solution
Control the strain distribution by moderating the change in compressive elastic stress during laser irradiation, ensuring a maximum stress difference of 4 MPa per 1 µm in the sheet thickness direction and adjusting irradiation parameters to meet specific formulae, thereby facilitating domain wall movement and reducing iron loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If laser irradiation is performed to refine magnetic domain width, then eddy-current loss is reduced, but strain variations hinder domain wall movement and iron loss reduction effectiveness
Solution Approach 1:
The invention changes the parameters of laser irradiation by controlling the strain distribution through moderating compressive elastic stress change. Specifically, it limits the compressive elastic stress change to 4 MPa or less per 1 µm in the sheet thickness direction, which optimizes the strain distribution to enable effective domain wall movement while maintaining refined magnetic domain width, thereby resolving the contradiction between reducing eddy-current loss and ensuring iron loss reduction effectiveness
Solution Approach 2:
The invention applies local quality control by creating a specific strain distribution pattern through controlled laser irradiation. By moderating the compressive elastic stress change locally in the sheet thickness direction, it ensures optimal conditions for domain wall movement in the irradiated regions while maintaining overall magnetic domain refinement, thus improving iron loss reduction effectiveness without sacrificing eddy-current loss reduction
2Length of moving object
If magnetic domain width is refined by laser irradiation, then eddy-current loss decreases, but domain wall movement is hindered by strain variations
Solution Approach 1:
The invention modifies the strain distribution parameters by controlling the compressive elastic stress change during laser irradiation. By limiting the stress change gradient to 4 MPa or less per 1 µm, it creates optimal conditions that allow domain walls to move freely while maintaining the refined magnetic domain width structure, thus resolving the contradiction between domain refinement and domain wall mobility
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
Achieves a lower iron loss in grain-oriented electrical steel sheets by ensuring controlled strain distribution and domain wall mobility, resulting in improved magnetic domain refinement and reduced iron loss.
Implementation Method 1
irradiating a grain-oriented electrical steel sheet with a laser beam while scanning the grain-oriented electrical steel sheet
Implementation Method 2
strain generated by irradiation with laser or the like is essential for a reduction in an iron loss
Data Source
Figure 1~2
AI summary
In a grain-oriented electrical steel sheet, in a cross section that is orthogonal to an extending direction of an irradiation trace of an energy ray, and is parallel to a sheet thickness direction, in a case where an imaginary line is drawn in the sheet thickness direction to include a position where compressive elastic stress measured by using EBSD is 20 MPa or more, the degree of change in the compressive elastic stress on the imaginary line is 4 MPa or less per 1 µm over the entire region in the sheet thickness direction.