Grain-Oriented Electrical Steel Surface Roughness for Lower Iron Loss
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Solution Overview
Problem
Existing grain-oriented electrical steel sheets face challenges in achieving favorable iron loss characteristics at high magnetic flux densities, and existing technologies fail to fully satisfy the demand for higher performance in these sheets.
Innovation Solution
A grain-oriented electrical steel sheet with a tension-insulation coating, where the underlying steel sheet has a controlled ten-point average roughness RzL in the rolling direction of 6.0 μm or less and RzC in the direction perpendicular to the rolling direction of 8.0 μm or less, with a RzL/RzC ratio less than 1.0, and arithmetic average roughness RaL and RaC values less than 0.4 μm and 0.6 μm, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inorganic coating is removed to improve magnetic characteristics, then magnetic characteristics are improved, but iron loss characteristics deteriorate
Solution Approach 1:
The patent applies local quality by creating an asymmetric surface roughness profile where the rolling direction (L-direction) has different roughness characteristics (RzL ≤ 6.0 μm) compared to the perpendicular direction (C-direction) with (RzC ≤ 8.0 μm) and RzL/RzC < 1.0. This directional differentiation optimizes both magnetic characteristics and iron loss characteristics simultaneously, resolving the contradiction between removing inorganic coatings for magnetic performance while maintaining energy efficiency.
2Reliability
If the surface roughness is reduced to improve magnetic characteristics, then magnetic characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The patent employs parameter changes by precisely controlling surface roughness parameters (RzL ≤ 6.0 μm, RzC ≤ 8.0 μm, RzL/RzC < 1.0, RaL < 0.4 μm, RaC < 0.6 μm) through optimized rolling and annealing processes. This approach achieves superior magnetic characteristics while avoiding overly complex surface treatment procedures by working within defined parameter ranges that can be controlled through standard manufacturing processes.
3Loss of energy
If a tension-applying coating is applied to achieve favorable iron loss characteristics, then iron loss characteristics are improved, but the inorganic coating must be removed first, adding process steps
Solution Approach 1:
The patent applies preliminary action by establishing the optimal surface roughness profile (RzL ≤ 6.0 μm, RzC ≤ 8.0 μm, RzL/RzC < 1.0) before applying the tension-applying coating. This preliminary surface preparation creates the ideal substrate conditions that enable the subsequent coating to achieve favorable iron loss characteristics without requiring complete removal of inorganic coatings, thereby reducing the number of process steps while maintaining performance.
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 enables the grain-oriented electrical steel sheet to achieve excellent B-W characteristics and improved iron loss characteristics, effectively addressing the limitations of existing technologies.
Implementation Method 1
the underlying steel sheet obtained by removing the tension-insulation coating from the grain-oriented electrical steel sheet with an alkaline solution
Implementation Method 2
local strain is applied to a steel sheet, a magnetic domain is subdivided, and the iron loss is reduced
Implementation Method 3
a solution containing colloidal silica and phosphate as main components is applied to a surface of a steel sheet after final annealing, baking is performed to form a tension-applying coating, and the iron loss is reduced
Data Source
AI summary
A grain-oriented electrical steel sheet according to an aspect of the present invention includes an underlying steel sheet and a tension-insulation coating arranged on the surface of the underlying steel sheet, and a ten-point average roughness RzL in an L direction obtained when the tension-insulation coating is removed from the grain-oriented electrical steel sheet with an alkaline solution, and then the surface of the underlying steel sheet is measured in a rolling direction is 6.0 μm or less.