Non-oriented Electrical Steel Sheet with Stabilized Magnetic Properties
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Solution Overview
Problem
Non-oriented electrical steel sheets with reduced Al content exhibit unstable magnetic properties when recycled, primarily due to the presence of Cu from scrap materials, which degrades their magnetic performance.
Innovation Solution
A non-oriented electrical steel sheet with a chemical composition of C ≤ 0.005%, Si 1.0% to 4.0%, Mn 0.10% to 3.0%, Sol. Al ≤ 0.002%, P 0.01% to 0.20%, S ≤ 0.005%, N ≤ 0.005%, Cu 0.02% to 0.10%, and Ca 0.0005% to 0.010%, optionally with Sn and Sb, is manufactured through hot rolling, pickling, cold rolling, and final annealing, with a coiling temperature of 650 °C or more to stabilize the magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the Al content is reduced to enhance magnetic flux density and improve recyclability, then the magnetic flux density is improved and recyclability is enhanced, but the magnetic property becomes unstable and iron loss increases
Solution Approach 1:
The patent changes the chemical composition parameters by strictly controlling Al content to 0.0020% or less and adding Cu (0.02-0.10%) and Ca (0.0005-0.0100%) to stabilize magnetic properties while reducing iron loss. This parameter optimization resolves the contradiction between low Al content and magnetic property stability.
Solution Approach 2:
The patent creates a composite material system with specific combinations of low Al, controlled Cu, and Ca elements to achieve stable magnetic properties. The synergistic effect of these elements compensates for the instability caused by low Al content alone.
2Adaptability or versatility
If scrap materials containing Cu are used to increase recyclability, then the recyclability is improved, but the magnetic property degrades
Solution Approach 1:
The patent converts the harmful effect of Cu (which degrades magnetic properties when present in scrap) into a beneficial factor by intentionally adding controlled amounts of Cu (0.02-0.10%) along with Ca (0.0005-0.0100%). This combination stabilizes magnetic properties even with scrap recycling, turning the previously harmful Cu into a useful element for property stabilization.
Solution Approach 2:
The patent optimizes the Cu content parameter to a specific range (0.02-0.10%) that allows beneficial use of Cu from scrap while preventing magnetic property degradation. This parameter control enables high recyclability with maintained reliability.
3Ease of manufacture
If the Al content is reduced below 0.05% to ensure castability of scrap, then the castability is improved, but the texture is insufficient and magnetic flux density is reduced
Solution Approach 1:
The patent optimizes Al content to a precise range (0.0020% or less) that ensures excellent castability of scrap while adding Cu and Ca to compensate for any texture deficiencies. This parameter optimization achieves both good castability and high magnetic flux density.
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 stabilizes the magnetic properties of the steel sheet, enhancing recyclability and reducing iron loss, thus contributing to environmental protection and resource conservation.
Implementation Method 1
a slab is heated at a temperature of 1050-1150°C, is subjected to hot rolling
Implementation Method 2
pickling an obtained hot rolled sheet
Implementation Method 3
final annealing the cold rolled sheet
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A non-oriented electrical steel sheet with excellent recyclability whose magnetic property is prevented from becoming unstable in the case of reducing the Al content in order to reuse the non-oriented electrical steel sheet as iron scrap is provided. The non-oriented electrical steel sheet has a chemical composition containing, in mass%: C: 0.0050% or less; Si: 1.0% or more and 4.0% or less; Mn: 0.10% or more and 3.0% or less; Sol. Al: less than 0.0050%; P: more than 0.01% and 0.20% or less; S: 0.0050% or less; N: 0.0050% or less; Cu: 0.02% or more and less than 0.10%; and Ca: 0.0005% or more and 0.0100% or less, with a balance being Fe and incidental impurities.