Non-Oriented Electrical Steel Soaking Window for Coating-Safe Annealing
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Solution Overview
Problem
Non-oriented electrical steel sheets face challenges in reducing iron loss and improving magnetic properties, while existing manufacturing processes are costly and inefficient, particularly due to prolonged heat treatment times and mechanical stress during processing.
Innovation Solution
A method involving final heat treatment with soaking at 850°C or higher for 1 to 30 minutes, followed by controlled cooling, to improve magnetic properties and reduce iron loss, incorporating specific chemical compositions and processing steps such as hot rolling, annealing, cold rolling, and insulation coating to optimize the steel sheet's properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heat treatment is performed to improve magnetic properties, then magnetic properties are improved, but heat treatment time is prolonged and manufacturing costs increase
Solution Approach 1:
The patent applies parameter changes by optimizing the heat treatment temperature to 850°C or higher and precisely controlling the soaking time between 1 to 30 minutes. This specific parameter range achieves the desired magnetic properties while minimizing heat treatment time, directly resolving the contradiction between improving magnetic properties and reducing heat treatment duration
Solution Approach 2:
The patent performs preliminary actions by conducting hot rolling and annealing processes before the final heat treatment. These preliminary steps prepare the steel sheet structure in advance, reducing the required soaking time during final heat treatment and thereby shortening the overall manufacturing cycle while maintaining magnetic property improvements
2Reliability
If high temperature heat treatment is performed to reduce iron loss, then magnetic properties are improved, but insulating coating may degrade
Solution Approach 1:
The patent applies parameter changes by setting the heat treatment temperature to 850°C or higher but precisely controlling the soaking time to 1-30 minutes. This optimized parameter combination achieves the necessary magnetic property improvement while limiting the duration of high temperature exposure, thereby preventing excessive degradation of the insulating coating
Solution Approach 2:
The patent applies partial action by using a soaking time that is sufficient (1-30 minutes) to achieve the desired magnetic properties but not excessive. This controlled partial exposure to high temperature accomplishes the necessary stress relief and magnetic property improvement without causing harmful degradation to the insulating coating
3Reliability
If mechanical stress is reduced to improve magnetic properties, then magnetic properties are improved, but processing time increases
Solution Approach 1:
The patent applies parameter changes by optimizing the heat treatment temperature to 850°C or higher, which accelerates the stress relief process. At this elevated temperature, atomic diffusion and stress relaxation occur more rapidly, achieving improved magnetic properties in just 1-30 minutes rather than requiring prolonged processing, thus maintaining high productivity
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 enhances magnetic properties, reduces iron loss, and lowers manufacturing costs by shortening heat treatment time, maintaining insulating coating integrity, and ensuring the steel sheet's suitability for high-efficiency motor applications.
Implementation Method 1
final heat treatment in which heating, soaking, and cooling are performed after processing the electrical steel sheet into parts for a motor
Implementation Method 2
The soaking may be maintained at a temperature of 850° C. or higher for 1 to 30 minutes to improve magnetic properties of the electrical steel sheet
Implementation Method 3
the cooling may be performed to room temperature (about 24° C.) at a cooling rate of 100° C. per hour
Data Source
AI summary
The present invention relates to a method for manufacturing a non-oriented electrical steel sheet, and a non-oriented electrical steel sheet manufactured thereby, and the method for manufacturing a non-oriented electrical steel sheet, according to the present invention, comprises the steps of: (a) reheating a steel slab comprising 0.05 wt % or less of C, 1.0-3.5 wt % of Si, 0.2-0.6 wt % of Al, 0.02-0.20 wt % of Mn, 0.01-0.20 wt % of P, 0.01 wt % or less of S, and the balance of Fe and inevitable impurities, and then performing hot rolling on same; (b) performing hot rolling annealing heat-treatment and pickling on a hot rolled steel sheet; (c) performing cold rolling on the pickled steel sheet; (d) performing insulation coating on the cold rolled steel sheet, and then processing same; and (e) performing final heat treatment by heating, soaking and cooling the processed steel sheet, wherein soaking process is maintained and carried out at a temperature of 850° C. or higher for 1-30 minutes, and thus the deterioration of an insulation coating layer is inhibited while magnetic properties are improved.