Non-oriented electrical steel sheet with controlled oxide inclusions
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Solution Overview
Problem
Conventional methods for producing non-oriented electrical steel sheets with high magnetic flux density and low iron loss at high frequencies are costly and inefficient, often requiring new equipment or process control, and are prone to issues like sheet breakage and increased production costs.
Innovation Solution
A non-oriented electrical steel sheet with a specific chemical composition and controlled oxide-based inclusion ratios, including decreased Mn and sol. Al contents, added Ca, and optional Sn and Sb, to enhance magnetic flux density without increasing production costs or requiring new equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If Si, Al, or Mn content is increased to reduce eddy current loss, then iron loss decreases, but magnetic flux density decreases
Solution Approach 1:
The invention changes the chemical composition parameters by precisely controlling Si content (1.5-5.0 mass%), Mn content (0.005-1.0 mass%), P content (0.05-0.2 mass%), and Al content (0.005-0.02 mass%), along with adding Ca (0.003-0.02 mass%), to achieve both low iron loss and high magnetic flux density simultaneously
2Strength
If P is added and Mn is decreased to increase magnetic flux density, then magnetic flux density increases, but sheet breakage occurs frequently in rolling steps
Solution Approach 1:
The invention optimizes the parameter combination by limiting Mn to 0.005-1.0 mass% (not excessively low), adding P within 0.05-0.2 mass%, and crucially adding Ca (0.003-0.02 mass%) to improve hot workability and prevent sheet breakage during rolling operations
Solution Approach 2:
Ca acts as an intermediary element that improves hot workability and prevents sheet breakage during rolling, allowing the use of P for magnetic flux density enhancement without suffering from the sheet breakage problem
3Strength
If Si content is kept low (0.1-1.0 mass%) to increase magnetic flux density, then magnetic flux density increases, but iron loss at high frequency zone becomes high
Solution Approach 1:
The invention sets Si content to 1.5-5.0 mass% (higher than the 0.1-1.0 mass% in Patent Document 1), which increases specific resistance to reduce eddy current loss at high frequencies, while compensating for the magnetic flux density reduction through optimized Mn (0.005-1.0 mass%), P (0.05-0.2 mass%), and Al (0.005-0.02 mass%) content and Ca addition
4Strength
If multiple cold rollings with intermediate annealing are used to increase magnetic flux density, then magnetic flux density increases, but production cost increases
Solution Approach 1:
The invention performs preliminary action by optimizing the chemical composition (Si: 1.5-5.0 mass%, Mn: 0.005-1.0 mass%, P: 0.05-0.2 mass%, Ca: 0.003-0.02 mass%) in the steel material before rolling, which enables high magnetic flux density to be achieved with a single cold rolling process, avoiding the need for multiple cold rollings with intermediate annealing
5Strength
If Mn content is decreased to increase magnetic flux density, then magnetic flux density increases, but iron loss properties deteriorate due to sulfide precipitation
Solution Approach 1:
The invention optimizes Mn content to 0.005-1.0 mass% (not excessively low), and adds P (0.05-0.2 mass%) and Ca (0.003-0.02 mass%) to achieve high magnetic flux density while preventing sulfide precipitation that would deteriorate iron loss properties, thus resolving the contradiction between magnetic flux density and iron loss properties
Data Source
AI summary
A non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss at not only a commercial frequency but also a high frequency zone, which has a chemical composition including C: not more than 0.0050 mass %, Si: more than 1.5 mass % but not more than 5.0 mass %, Mn: not more than 0.10 mass %, sol. Al: not more than 0.0050 mass, P: more than 0.040 mass % but not more than 0.2 mass %, S: not more than 0.0050 mass %, N: not more than 0.0040 mass % and Ca: 0.001-0.01 mass % and the remainder being Fe and inevitable impurities and a compositional ratio of CaO in oxide-based inclusions existing in a steel sheet of not less than 0.4 and/or a compositional ratio of Al2O3 of not less than 0.3, and a hot rolled steel sheet used as a raw steel material thereof.