Non-Oriented Electrical Steel Composition Without Hot-Rolled Annealing
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Solution Overview
Problem
The existing manufacturing process for non-oriented electrical steel sheets requires hot-rolled sheet annealing, which increases manufacturing costs and can deteriorate cold-rolling properties, while also posing challenges in optimizing magnetic properties.
Innovation Solution
A non-oriented electrical steel sheet and manufacturing method that omit hot-rolled sheet annealing, achieving improved magnetism by controlling alloy compositions and process conditions, such as heating, hot-rolling, cold-rolling, and final annealing, to satisfy specific formulas and conditions that enhance magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hot-rolled sheet annealing is performed to improve magnetic properties, then iron loss is reduced and magnetic flux density is improved, but manufacturing cost increases and cold-rolling properties deteriorate
Solution Approach 1:
The patent extracts and eliminates the hot-rolled sheet annealing process from the manufacturing sequence. By developing a slab composition specifically optimized for direct hot-rolling followed by cold-rolling, the patent removes the intermediate annealing step that causes manufacturing cost increases and productivity issues, while maintaining excellent magnetic properties through controlled composition and process parameters
Solution Approach 2:
The patent changes the compositional parameters of the steel slab, specifically controlling Si content at 0.5-2.4 wt%, Mn at 0.4-1.0 wt%, and Al at 0.01-0.10 wt%, along with other elements. These parameter changes enable the material to achieve desired magnetic properties and cold-rolling characteristics without requiring intermediate annealing, thus resolving the contradiction between magnetic performance and manufacturing efficiency
2Loss of energy
If Si, Al, and Mn addition amounts are increased to reduce iron loss, then specific resistance increases and eddy current loss decreases, but magnetic flux density deteriorates
Solution Approach 1:
The patent applies precise parameter control by limiting Si to 0.5-2.4 wt%, Mn to 0.4-1.0 wt%, and Al to 0.01-0.10 wt%, rather than increasing these elements indiscriminately. This controlled composition achieves sufficient specific resistance to reduce eddy current loss while preventing excessive alloying that would harm magnetic flux density, thus resolving the contradiction between iron loss reduction and magnetic flux density maintenance
Solution Approach 2:
The patent creates a composite alloy system where Si, Mn, and Al work synergistically in controlled proportions. This composite approach allows the material to achieve both high specific resistance (for low eddy current loss) and adequate magnetic flux density by balancing the contributions of different alloying elements rather than relying on any single element in excess
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 method allows for the production of non-oriented electrical steel sheets with excellent magnetic properties, reduced iron loss, and high magnetic flux density, while also lowering manufacturing costs and improving productivity.
Implementation Method 1
a method for improving the texture is widely used by performing a hot-rolled sheet annealing process before cold-rolling a hot-rolled sheet after hot-rolling a slab for a purpose of improving the texture
Implementation Method 2
there is a method of increasing addition amounts of Si, Al, and Mn, which are elements with high specific resistance. However, increasing the addition amount of Si, Al, and Mn increases the specific resistance of the steel, thereby reducing the eddy current loss among the iron loss
Data Source
AI summary
A non-oriented electrical steel sheet according to an embodiment of the present invention includes, in wt %, C at 0.005% or less (excluding 0%), Si at 0.5 to 2.4%, Mn at 0.4 to 1.0%, S at 0.005% or less (excluding 0%), Al at 0.01% or less (excluding 0%), N at 0.005% or less (excluding 0%), Ti at 0.005% or less (excluding 0%), Cu at 0.001 to 0.02%, and the balance of Fe and inevitable impurities, and satisfies Formula 1 below, wherein a volume fraction of grains in which an angle formed by a {111} surface and a rolling surface of the steel sheet is 15° or less is 27% or more.[Mn]/([Si]+150×[Al])≤0.35[Formula 1](In Formula 1, [Mn], [Si], and [Al] are contents (wt %) of Mn, Si, and Al, respectively.)