Non-oriented Electrical Steel Sheet Grain Boundary Segregation
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Solution Overview
Problem
Conventional methods fail to produce non-oriented electrical steel sheets with high magnetic flux density and low iron loss at high frequencies while maintaining good productivity and low costs, often resulting in increased production costs and sheet breakage issues.
Innovation Solution
A non-oriented electrical steel sheet with a specific chemical composition, including C, Si, Mn, sol. Al, P, S, N, and optional additions of Sn, Sb, Ca, REM, Mg, Ni, Cu, and Cr, where the P content is optimized to segregate on the crystal grain boundary, reducing iron loss without decreasing magnetic flux density, achieved through controlled annealing and heat treatment processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the addition amount of elements enhancing specific resistance (Si, Al, Mn) is increased, then iron loss is decreased, but saturated magnetic flux density is decreased
Solution Approach 1:
The patent optimizes the chemical composition parameters by precisely controlling the content ranges of Si (1.5-4.0 mass%), Al (0.003-3.0 mass%), Mn (0.005-11.5 mass%), and P (0.03-0.20 mass%). This parameter optimization allows achieving low iron loss through enhanced specific resistance while preventing excessive reduction of magnetic flux density by balancing the additive effects and detrimental interactions between these elements.
Solution Approach 2:
The patent creates a composite chemical composition system combining multiple alloying elements (Si, Al, Mn, P) in specific proportions. This composite approach leverages the beneficial effects of each element: Si and Al enhance specific resistance to reduce eddy current loss, while Mn and P control texture development to maintain magnetic flux density, achieving a balanced performance that individual elements cannot provide alone.
2Loss of energy
If the thickness of the steel sheet is decreased, then iron loss is reduced, but crystal orientation becomes disadvantageous and magnetic flux density decreases
Solution Approach 1:
The patent optimizes the thickness parameter within the range of 0.10-0.50 mm, finding the optimal balance between reducing eddy current loss (which benefits from thinner sheets) and maintaining favorable crystal orientation (which requires sufficient thickness for proper texture development during rolling and annealing processes).
3Strength
If P content is increased to enhance magnetic flux density, then production troubles such as sheet breakage occur and productivity decreases
Solution Approach 1:
The patent precisely controls the P content within 0.03-0.20 mass%, which is sufficient to enhance magnetic flux density through texture control but below the threshold that causes severe embrittlement and production troubles. This optimized parameter range achieves the desired magnetic properties while maintaining production continuity.
Solution Approach 2:
The patent introduces P as an intermediary element that mediates between texture development (affecting magnetic flux density) and embrittlement (affecting productivity). By controlling P within the optimal range and combining it with other elements like Si, Al, and Mn, the patent achieves favorable crystal orientation for high magnetic flux density while preventing excessive embrittlement that would cause sheet breakage.
4Strength
If box annealing is used to control texture and enhance magnetic flux density, then production cost increases
Solution Approach 1:
The patent optimizes the chemical composition parameters (Si: 1.5-4.0 mass%, Al: 0.003-3.0 mass%, Mn: 0.005-11.5 mass%, P: 0.03-0.20 mass%) to achieve favorable crystal orientation and high magnetic flux density through composition control rather than relying exclusively on expensive box annealing processes, thereby reducing production costs 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
The solution provides a steel sheet with high magnetic flux density and excellent iron loss properties at high frequencies, ensuring high motor output and efficiency while maintaining cost-effectiveness and productivity.
Implementation Method 1
the P content is optimized to segregate on the crystal grain boundary, reducing iron loss without decreasing magnetic flux density
Implementation Method 2
achieved through controlled annealing and heat treatment processes
Data Source
AI summary
A non-oriented electrical steel sheet having a chemical composition comprising C: not more than 0.010 mass %, Si: 1.0-7.0 mass %, Mn: 0.001-3.0 mass %, sol. Al: 0.0001-3.5 mass %, P: 0.01-0.2 mass %, S: not more than 0.010 mass %, N: not more than 0.010 mass % and the remainder being Fe and inevitable impurities, wherein a ratio (P120/Fe700) of a peak-peak height P120 of P near to an electronic energy of 120 eV to a peak-peak height Fe700 of Fe near to an electronic energy of 700 eV in an Auger differential spectrum obtained by analyzing a broken surface of a grain boundary through Auger electron spectroscopy is not less than 0.1 and a sheet thickness is 0.10-0.50 mm, and a motor using such a non-oriented electrical steel sheet as an iron core.