Non-oriented electrical steel sheet with optimized alloy composition and accelerated hot rolling
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Solution Overview
Problem
Existing non-oriented electrical steel sheets face challenges in maintaining uniform temperature during hot rolling, leading to surface defects and compromised magnetic properties, particularly in thin sheets used for environmentally-friendly vehicle motors.
Innovation Solution
A non-oriented electrical steel sheet composition with specific alloy percentages (Si: 3.0 to 5.0%, Mn: 0.1 to 1.4%, Al: 0.3 to 1.3%) and a manufacturing process involving accelerated rolling speeds during hot rolling to minimize temperature deviations, ensuring a uniform surface and improved magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If alloying elements (Si, Al, Mn) are added to improve magnetic properties and strength, then iron loss decreases and strength increases, but magnetic flux density deteriorates and brittleness increases
Solution Approach 1:
The patent optimizes the content ranges of alloying elements (Si: 2.0-5.0%, Al: 0.1-1.3%, Mn: 0.1-1.4%) to achieve the best balance between iron loss reduction and magnetic flux density maintenance. This parameter optimization resolves the contradiction by finding the optimal composition window where energy loss is minimized while magnetic performance remains high.
Solution Approach 2:
The patent creates a composite alloy system combining Si, Al, and Mn in specific proportions to achieve synergistic effects. Si provides electrical resistance increase for lower iron loss, Al contributes to strength and surface quality, and Mn enhances magnetic properties. The composite composition resolves the contradiction by leveraging the complementary strengths of different elements.
2Shape
If hot rolling temperature is increased to improve surface shape, then surface quality improves, but temperature deviation along the coil length increases
Solution Approach 1:
The patent applies dynamic control of rolling speed during the hot rolling process, implementing accelerated rolling where the rolling speed increases progressively along the coil length. This dynamic speed adjustment compensates for temperature deviation, ensuring uniform surface quality throughout the coil while maintaining the benefits of elevated rolling temperature.
Solution Approach 2:
The patent implements feedback control by monitoring temperature distribution along the coil and adjusting rolling parameters accordingly. The accelerated rolling profile is designed based on expected temperature gradients, creating a feedback mechanism that maintains uniform surface properties despite temperature variations during the rolling process.
3Manufacturing precision
If rolling speed is increased to reduce temperature deviation, then surface uniformity improves, but manufacturing complexity increases
Solution Approach 1:
The patent implements a dynamically adjustable rolling speed system that can be programmed with predetermined acceleration profiles. This dynamic control achieves uniform surface quality through speed variation while keeping the control system relatively simple by using pre-programmed patterns rather than complex real-time adjustments.
Solution Approach 2:
The patent changes the rolling speed parameter during the hot rolling process, implementing accelerated rolling where speed increases along the coil length. This parameter change simplifies the control strategy compared to maintaining constant high speed, as it uses a predictable progression pattern that is easier to implement and control.
Data Source
AI summary
A non-oriented electrical steel sheet according to an embodiment of the present invention includes, in wt%, Si: 3.0 to 5.0%, Mn: 0.1 to 1.4%, and Al: 0.3 to 1.3%, with the balance being Fe and inevitable impurities. In the non-oriented electrical steel sheet according to the embodiment of the present invention, when a 5 mm × 5 mm area on the surface is observed, the length of unevenness having a height difference of 1.0 µm or more compared to the average height may be 3 mm or less.