Non-Oriented Electrical Steel Texture for Low High-Frequency Core Loss
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Solution Overview
Problem
Existing non-oriented electrical steel sheets face challenges in achieving low core loss at high frequencies and maintaining uniform magnetic properties, which are critical for energy efficiency in applications such as electric vehicle motors.
Innovation Solution
A non-oriented electrical steel sheet is developed with specific chemical compositions, including silicon (Si), manganese (Mn), aluminum (Al), and controlled microstructure and texture, achieved through a manufacturing process involving hot rolling, first annealing, cold rolling, and second annealing, to optimize grain size and orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional non-oriented electrical steel sheets are used, then they provide uniform magnetic properties in all directions, but they exhibit high core loss at high frequencies
Solution Approach 1:
The patent applies parameter changes by precisely controlling chemical composition parameters (Si: 2.0-3.5 wt%, Mn: 0.10-0.50 wt%, Al: 0.05-1.00 wt%) and microstructural parameters (grain size 50-150 μm, specific orientation distributions) to achieve low core loss while maintaining magnetic property uniformity. The controlled composition and microstructure enable reduced eddy current losses at high frequencies without sacrificing the isotropic magnetic characteristics needed for reliable motor operation
Solution Approach 2:
The patent creates a composite microstructure combining multiple grain orientations ({100}<100>, {110}<100>, and cubic textures) with specific volume fractions. This composite texture structure, achieved through controlled rolling and annealing processes, provides both low core loss characteristics and uniform magnetic properties in all directions, effectively resolving the contradiction between energy efficiency and reliability
2Loss of energy
If grain size is reduced to lower core loss, then eddy current loss decreases, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the grain size parameter to a specific range (50-150 μm) that balances eddy current loss reduction with manufacturing feasibility. This parameter optimization, combined with controlled chemical composition (particularly Si and Al content), achieves sufficient core loss reduction without requiring excessively precise manufacturing control that would increase production complexity and cost
3Loss of energy
If alloying elements are increased to improve magnetic properties, then core loss decreases, but production cost increases
Solution Approach 1:
The patent optimizes alloying element parameters to achieve the minimum effective concentrations needed for core loss reduction. Specifically, Si is controlled at 2.0-3.5 wt% (provides electrical resistivity increase), Mn at 0.10-0.50 wt% (improves magnetic properties), and Al at 0.05-1.00 wt% (refines grain structure). This parameter optimization achieves satisfactory core loss reduction while avoiding excessive alloying that would significantly increase production costs
Solution Approach 2:
The patent employs a balanced alloying strategy that uses moderate amounts of cost-effective elements (Si, Mn, Al) rather than expensive rare earth elements. This approach achieves acceptable core loss performance at lower material costs, making the steel sheet economically viable for mass production in motor applications
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 achieves a core loss of 13.5 W/kg or less and a standard deviation of 0.725 W/kg or less, ensuring uniform magnetic properties and low core loss at high frequencies, while also controlling production costs by limiting temperature and grain size in preliminary annealing.
Implementation Method 1
silicon (Si): 2.0 wt % to 3.5 wt %, which contributes to increasing electrical resistivity and reducing core loss
Implementation Method 2
first annealing the hot-rolled steel material, and second annealing the cold-rolled steel material
Implementation Method 3
the first annealing is performed under conditions of a heating rate: 10° C./s or more, an annealing start temperature: 900° C. to 1050° C., an annealing holding time: 30 sec. to 90 sec., and a cooling rate: 20° C./s or more
Implementation Method 4
hot rolling the steel material, cold rolling the first-annealed steel material
Data Source
AI summary
Provided is a non-oriented electrical steel sheet including silicon (Si): 2.8 wt % to 3.8 wt %, manganese (Mn): 0.2 wt % to 0.5 wt %, aluminum (Al): 0.5 wt % to 1.2 wt %, carbon (C): more than 0 wt % and not more than 0.002 wt %, phosphorus (P): more than 0 wt % and not more than 0.015 wt %, sulfur (S): more than 0 wt % and not more than 0.002 wt %, nitrogen (N): more than 0 wt % and not more than 0.002 wt %, titanium (Ti): more than 0 wt % and not more than 0.002 wt %, and a balance of iron (Fe) and unavoidable impurities, wherein, in a final microstructure, grains with {111}//ND orientation have a volume fraction of 30% or less and an average misorientation angle of 23° or more, and grains with {001}//ND orientation have a volume fraction of 15% or more and an average misorientation angle of 48° or more.