Non-Oriented Electrical Steel Sheet With Tight Thickness Control
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Solution Overview
Problem
Existing non-oriented electrical steel sheets face challenges in reducing sheet thickness deviation without performing hot rolled plate annealing, which affects magnetic properties and increases manufacturing costs.
Innovation Solution
A non-oriented electrical steel sheet is manufactured by hot-rolling a slab with specific compositions, followed by multiple acid pickling processes and cold-rolling, without performing hot rolled plate annealing. The final pass reduction ratio in hot rolling is adjusted to control thickness deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hot rolled plate annealing is performed to improve magnetic properties and reduce thickness deviation, then magnetic flux density and surface characteristic are improved, but manufacturing cost increases and productivity decreases due to additional process steps
Solution Approach 1:
The patent removes the hot rolled plate annealing process from the manufacturing sequence, extracting this intermediate heat treatment step while maintaining final product quality through direct cold rolling of the hot rolled plate
Solution Approach 2:
The patent optimizes the composition parameters (Si: 1.4-3.0%, Mn: 0.001-1.5%, Al: 0.001-0.2%) and hot rolling parameters (final pass reduction ratio: 10-20%) to achieve the required thickness deviation control without annealing
2Reliability
If hot rolled plate annealing is performed to improve magnetic properties, then iron loss and magnetic flux density are improved, but manufacturing cost increases due to addition of process steps
Solution Approach 1:
The patent eliminates the hot rolled plate annealing process step, removing the associated manufacturing cost while preserving magnetic properties through optimized composition and direct cold rolling
Solution Approach 2:
The patent adjusts composition parameters (particularly Si content at 1.4-3.0% for high resistivity) and hot rolling parameters (final pass reduction ratio at 10-20%) to achieve excellent magnetic properties without the need for intermediate annealing
3Loss of energy
If alloy elements (Si, Al, Mn) are increased to reduce iron loss, then resistivity increases and Eddy current loss decreases, but magnetic flux density deteriorates
Solution Approach 1:
The patent optimizes the composition parameters within specific ranges (Si: 1.4-3.0%, Mn: 0.001-1.5%, Al: 0.001-0.2%) to balance resistivity enhancement for reduced Eddy current loss while maintaining adequate magnetic flux density
Solution Approach 2:
The patent creates a composite alloy system combining Si, Mn, and Al in optimized proportions, where Si provides high resistivity for reduced Eddy current loss, while Mn and Al contribute to maintaining magnetic flux density and overall magnetic properties
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 method effectively reduces sheet thickness deviation, improves magnetic properties, and lowers manufacturing costs by eliminating the need for hot rolled plate annealing, thereby enhancing the efficiency of motors using these steel sheets.
Implementation Method 1
performing acid pickling a plurality of times after hot rolling
Data Source
AI summary
A non-oriented electrical steel sheet according to one embodiment of the present invention comprises, by wt %, 1.4-3.0% of Si; 0.001-1.5% of Mn; and 0.001-0.2% of Al, with the remainder of Fe and inevitable impurities, wherein a thickness deviation in the direction perpendicular to a rolling direction is 1.5 μm or less per 5 mm length, and a thickness derivation in the rolling direction is 10 μm or less per 1000 m length.