Grain-Oriented Steel Sheet Coating Adhesion and Core Loss
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Solution Overview
Problem
Conventional grain-oriented electrical steel sheets face challenges in achieving high tension coating films with excellent adhesiveness and magnetic properties due to insufficient interface structure optimization between the glass coating film and the steel sheet.
Innovation Solution
A grain-oriented electrical steel sheet with a composition of Si, Mn, B, Al, C, N, S, and Se, featuring a glass coating film composed of composite oxide with forsterite, where the secondary coating film is formed with colloidal silica, chromic anhydride, and aluminum biphosphate, and subjected to glow discharge optical emission spectrometry to optimize the peak positions of B and Mg emission intensity, ensuring a specific peak occurrence time ratio that enhances adhesiveness and magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the glass coating film is formed by reacting SiO2 in the steel sheet and MgO of an annealing separating agent, then the coating film can be formed on the steel sheet surface, but the adhesiveness between the glass coating film and the steel sheet is insufficient
Solution Approach 1:
The invention changes the chemical composition parameters of the steel sheet by adding specific elements (Ti: 0.003-0.03 mass%, V: 0.003-0.03 mass%, Nb: 0.003-0.03 mass%, and/or Ta: 0.003-0.03 mass%) to modify the interface structure between the glass coating film and steel sheet, thereby improving adhesiveness
Solution Approach 2:
The invention creates a composite structure at the interface by introducing refractory metal elements that form complex compounds between the steel sheet and glass coating film, enhancing the interfacial bonding and overall adhesiveness
2Stability of the object's composition
If sulfide or nitride inhibitors are used to cause secondary recrystallization, then the Goss orientation can be achieved, but the core loss deteriorates when inhibitors are retained in the product
Solution Approach 1:
The invention changes the inhibitor composition from conventional sulfide or nitride to refractory metal carbides/nitrides containing Ti, V, Nb, and/or Ta, which provide effective pinning for secondary recrystallization while being easier to remove during purification annealing, thus reducing core loss
Solution Approach 2:
The invention facilitates the removal (discarding) of inhibitor elements during purification annealing by using refractory metal-based inhibitors that can be effectively eliminated through prolonged high-temperature treatment in pure hydrogen, thereby recovering the magnetic properties of the steel sheet
3Loss of energy
If the steel sheet is retained for a long time in pure hydrogen at around 1200°C for purification annealing, then the effect of sulfide and nitride can be removed, but the manufacturing time increases
Solution Approach 1:
The invention changes the inhibitor composition to refractory metal-based compounds that decompose or dissolve more rapidly during purification annealing compared to conventional sulfide or nitride inhibitors, enabling effective purification in shorter times (0.5-2 hours) while maintaining low core loss
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 proposed method results in a grain-oriented electrical steel sheet with improved coating film adhesiveness and magnetic properties, achieving high tension and low core loss, while stabilizing secondary recrystallization and preventing excessive strength reduction.
Implementation Method 1
SiO 2 in the steel sheet and MgO of an annealing separating agent main component react and thereby the glass coating film is formed on the steel sheet
Implementation Method 2
glow discharge optical emission spectrometry (GDS) to the surface of the secondary coating film is performed
Implementation Method 3
by tension that these coating films apply to the steel sheet, a magnetic domain control effect is obtained and the low-core loss property is improved
Implementation Method 4
grain growth called secondary recrystallization in which Goss oriented grains selectively grow during finish annealing
Implementation Method 5
The inhibitor suppresses the grain growth in a low-temperature portion during finish annealing and at a certain temperature or higher, loses its pinning effect by decomposition or coarsening
Implementation Method 6
In order to remove an effect of sulfide and nitride from the steel sheet, after the secondary recrystallization is completed, the steel sheet is retained for a long time in pure hydrogen at around 1200°C
Data Source
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AI summary
A grain-oriented electrical steel sheet being a grain-oriented electrical steel sheet containing Si of 0.8 mass% to 7 mass%, Mn of 0.05 mass% to 1 mass%, B of 0.0005 mass% to 0.0080 mass%, Al of 0.025 mass% or less in a content ratio, each content of C, N, S, and Se of 0.005 mass% or less, and a balance being composed of Fe and inevitable impurities and having a glass coating film made of composite oxide mainly composed of forsterite on the steel sheet surface, in which when glow discharge optical emission spectrometry (GDS) to the surface of a secondary coating film formed on the surface of the glass coating film under a predetermined condition is performed, a peak, of B, in emission intensity having a peak position in emission intensity different from a peak position, of Mg, in emission intensity is obtained and the peak position, of B, in emission intensity from the steel sheet surface is deeper than the peak position, of Mg, in emission intensity.