Grain-Oriented Steel Sheet Strain Distribution for Low Iron Loss
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Solution Overview
Problem
Conventional methods for reducing iron loss in grain-oriented electrical steel sheets either increase hysteresis loss or eddy current loss, and simultaneously reducing noise is challenging due to the deformation caused by internal stress release in transformers.
Innovation Solution
Optimizing the distribution of tensile and compressive strains in the steel sheet by adjusting the conditions of high-energy beam irradiation, such as laser or electron beam, to restrict expansion in the rolling direction and facilitate expansion in the sheet thickness direction, with a specific strain distribution that satisfies the conditions t + 0.06 ≤ t + c ≤ 0.35, where t is the maximum tensile strain in the sheet thickness direction and c is the maximum compressive strain in the rolling direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If crystal orientations are made in accord with the Goss orientation to improve flux density, then flux density increases, but magnetostatic energy decreases causing magnetic domain width to widen and eddy current loss to rise
Solution Approach 1:
The patent applies thermal strain treatment by heating the electrical steel sheet to a specific temperature range (Ac1 point to Ac3 point) and maintaining it for a predetermined time, then rapidly cooling it. This parameter change in temperature and time modifies the magnetic domain structure, refining the domain width to compensate for the widening effect caused by Goss orientation, thereby reducing eddy current loss while preserving high flux density.
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 optimized strain distribution results in extremely low iron loss and noise levels, enabling the production of transformers with high efficiency and reduced noise, suitable for various environments.
Implementation Method 1
magnetic domain refining by application of thermal strain is performed using plasma flame irradiation, laser irradiation, electron beam irradiation and the like
Implementation Method 2
JP H03-13293 B2 (PTL 4) discloses a method for reducing iron loss by applying laser irradiation to a steel sheet
Implementation Method 3
JP H07-65106 B2 (PTL 3) discloses a method for producing an electrical steel sheet having a reduced iron loss W 17/50 of below 0.8 W/kg due to electron beam irradiation
Data Source
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Figure 3(a)~3(b)
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AI summary
Provided is a grain-oriented electrical steel sheet that allows for manufacture of a transformer that exhibits, when the steel sheet is applied to an iron core thereof, extremely low iron loss and extremely low noise properties, makes highly efficient use of energy, and can be used in various environments. The grain-oriented electrical steel sheet according to the present invention has a strain distribution in regions where closure domains are formed, when observed in a cross section in the rolling direction, with a maximum tensile strain in a sheet thickness direction being 0.45 % or less, and with a maximum tensile strain t (%) and a maximum compressive strain c (%) in the rolling direction satisfying the following Expression (1): t+0.06≤t+c≤0.35