Grain-Oriented Steel Sheet Lateral Strain Control via Glass Coating
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Solution Overview
Problem
Existing methods for reducing lateral strain in grain-oriented electrical steel sheets during final annealing either fail to accurately control grain size, leading to uneven magnetic properties or require costly and inefficient high-power laser systems, and often result in abnormal crystal grains that deteriorate the magnetic quality.
Innovation Solution
A grain-oriented electrical steel sheet with a glass coating film featuring a linearly altered portion along one side edge, where the composition differs from the rest of the film, is produced by radiating a laser beam onto the SiO2 coating film to create a locally deformable area that suppresses lateral strain without affecting the base metal iron portion's magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a laser beam is radiated onto the base metal iron portion to generate an easy deformable portion, then lateral strain propagation is suppressed, but abnormal crystal grains are generated and magnetic properties are deteriorated
Solution Approach 1:
The invention applies local quality by creating an easy deformable portion specifically in the glass coating film rather than the base metal. The laser beam is radiated onto the glass coating film to generate a linear altered portion with different composition (lower MgO content), creating localized deformation capability at the surface level while preserving the crystal grain structure and magnetic properties of the underlying base metal iron portion.
2Manufacturing precision
If high-power laser systems are used to reduce lateral strain, then deformation control is improved, but production cost and system complexity increase
Solution Approach 1:
The invention changes the parameter of laser power to a low level (100W or less), transforming the approach from high-power deformation of base metal to low-power modification of glass coating film composition. This parameter change enables the use of simple, low-cost laser systems while achieving the desired lateral strain control through compositional alteration of the coating film.
3Object-affected harmful factors
If the glass coating film composition is altered locally, then lateral strain propagation is suppressed, but the uniformity of the coating film is reduced
Solution Approach 1:
The invention intentionally creates local compositional variation in the glass coating film by radiating the laser beam to generate a linear altered portion with lower MgO content. This local quality change is confined to a narrow linear region and does not compromise the overall uniformity and protective function of the glass coating film, while effectively suppressing lateral strain propagation at the steel sheet surface.
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 approach effectively reduces lateral strain propagation and maintains stable magnetic properties across the steel sheet, enhancing the quality and yield of the grain-oriented electrical steel sheet production by locally deforming the glass coating film and avoiding abnormal crystal grain formation.
Implementation Method 1
radiating a laser beam onto the SiO2 coating film to create a locally deformable area
Implementation Method 2
the SiO2 coating film and the magnesia-based annealing separator react with each other, thereby forming the aforementioned glass coating film
Data Source
Figure 1~3
Figure 4~5
Figure 6A
AI summary
[Object] To provide a grain oriented electrical steel sheet that can securely suppress propagation of lateral strain, and can make a product even from a portion where the lateral strain occurs. [Solution] A grain oriented electrical steel sheet of the present invention has a linearly altered portion 14 generated in a glass coating film 12 at one of side edges of a steel sheet 11, in a continuous line or in a discontinuous broken line in a direction parallel with a rolling direction of the steel sheet, and having a composition different from a composition in other portions of the glass coating film. An average value of a deviation angle of a direction of an axis of easy magnetization of crystal grains relative to the rolling direction is 0° or more and 20° or less in a base metal iron portion of the steel sheet 11 at a position along a width direction of the steel sheet, the position corresponding to the linearly altered portion 14.