Electron Beam Strain Regions in Grain-Oriented Electrical Steel

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Solution Overview

Problem

Grain-oriented electrical steel sheets without a forsterite film face challenges in achieving good adhesion of the insulation coating and reducing iron loss, as high-energy density laser or electron beam radiation can refine magnetic domains but compromise coating adhesion.

Innovation Solution

A method involving the formation of a strain region on the base steel sheet using an electron beam under specific conditions, with an intermediate layer and insulation coating, to ensure good adhesion and iron loss reduction, where the electron beam is scanned with controlled parameters to form a strain region intersecting the rolling direction, and the insulation coating is applied with a solution of phosphate and colloidal silica.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If high-energy density laser or electron beam radiation is applied to refine magnetic domains, then iron loss is reduced, but coating adhesion deteriorates

Engineering Contradiction:
Improveiron lossVSAvoidcoating adhesion
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The patent applies low-energy density electron beam radiation (0.1-10 W/mm²) instead of high-energy density radiation, fundamentally changing the energy parameter to achieve magnetic domain refinement while preserving coating adhesion. This parameter change allows the insulation coating to withstand the radiation process without peeling while still achieving the desired magnetic domain structure.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The insulation coating is applied to the steel sheet before electron beam irradiation. This preliminary action ensures that the coating is already in place to protect the steel sheet during the magnetic domain refinement process, preventing the coating adhesion deterioration that would occur with high-energy radiation.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If an intermediate layer is formed on the base steel sheet, then coating adhesion is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvecoating adhesionVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The steel sheet surface itself serves as the substrate for the insulation coating without requiring an additional intermediate layer. The electron beam irradiation directly treats the steel sheet surface, and the insulation coating adheres directly to the irradiated surface, eliminating the need for a separate intermediate layer and simplifying the manufacturing process.

Inventive Principle:
Principle #25Self-service

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 method ensures excellent adhesion of the insulation coating and reduces iron loss in grain-oriented electrical steel sheets without a forsterite film, while maintaining the magnetic domain refining effect.

Implementation Method 1

irradiating the steel sheet with an electron beam to form a strain region

Methodology Applied
Scientific EffectElectron beam: Electron Beam

Implementation Method 2

a temperature of a central portion of the strain region in a rolling direction and an extension direction of the strain region is heated to 800°C or higher and 2000°C or lower

Methodology Applied
Scientific EffectElectron beam heating: Electron Beam

Data Source

PatentEP3913088B1Method for manufacturing grain-oriented electrical steel sheet
Publication Date: 2024.05.22 NIPPON STEEL CORPORATION
  • EP3913088B1 patent drawingFigure 1~2
  • EP3913088B1 patent drawingFigure 3~4
  • EP3913088B1 patent drawingFigure 5

AI summary

The method for manufacturing a grain-oriented electrical steel sheet is a method for manufacturing a grain-oriented electrical steel sheet including a strain region forming process of irradiating the grain-oriented electrical steel sheet having a base steel sheet (1), an intermediate layer (4) disposed to be in contact with the base steel sheet (1), and an insulation coating (3) disposed to be in contact with the intermediate layer (4) with an electron beam and forming a strain region (D) which extends in a direction intersecting a rolling direction of the base steel sheet (1) on a surface of the base steel sheet (1), wherein, in the strain region forming process, a temperature of a central portion of the strain region (D) in the rolling direction of the base steel sheet (1) and an extension direction of the strain region (D) is heated to 800°C or higher and 2000°C or lower.