Non-oriented electrical steel sheet with suppressed Si-Mn nitrides
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Solution Overview
Problem
Non-oriented electrical steel sheets with high Si and Mn content but low Al face challenges in reducing iron loss while maintaining recyclability, as conventional methods either increase viscosity during recycling or lead to undesirable shrinkage cavities.
Innovation Solution
By controlling the coiling temperature after hot rolling and adjusting the Mn content, the precipitation of Si-Mn nitrides is suppressed, improving grain growth properties and reducing iron loss without adding Al, thus enhancing magnetic properties and recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If Al is added to reduce iron loss, then magnetic properties improve, but viscosity increases during recycling causing shrinkage cavities
Solution Approach 1:
The patent changes the chemical composition parameters by adding Si (1.0-3.0%) and Mn (1.5-3.0%) instead of Al, and controls the coiling temperature (500-650°C) to achieve the desired balance between magnetic properties and recyclability
Solution Approach 2:
The patent uses Si and Mn as alternative alloying elements that serve the function of reducing iron loss without the harmful side effects of Al during recycling, effectively replacing the problematic element with more suitable alternatives
2Loss of energy
If Si and Mn content is increased to reduce iron loss, then magnetic properties improve, but Si-Mn nitride precipitation increases reducing grain growth
Solution Approach 1:
The patent optimizes the coiling temperature parameter (500-650°C) to control the precipitation behavior of Si-Mn nitrides, and adjusts the composition parameters (Si: 1.0-3.0%, Mn: 1.5-3.0%, N: 0.003-0.030%) to achieve the desired balance between iron loss reduction and grain growth
Solution Approach 2:
The patent applies preliminary anti-action by controlling the coiling temperature to suppress Si-Mn nitride precipitation before the final annealing process, preventing the harmful effect from occurring in the first place
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 effectively reduces iron loss in non-oriented electrical steel sheets by controlling coiling temperature and Mn content, improving grain growth and magnetic properties while ensuring recyclability without Al, which addresses the limitations of existing techniques.
Implementation Method 1
suppress the precipitation of Si-Mn nitrides
Implementation Method 2
improving the grain growth property during final annealing
Implementation Method 3
hot rolling to a thickness of 2.0 mm
Implementation Method 4
coiling treatment was performed at a temperature of 650 °C
Implementation Method 5
final annealing was performed at 1000 °C for 10 s in an atmosphere of 20 vol% H 2 -80 vol% N 2
Data Source
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AI summary
Disclosed is a non-oriented electrical steel sheet low in iron loss that is substantially free of Al and contains large amounts of Si and Mn. The disclosed non-oriented electrical steel sheet has a chemical composition containing C: 0.0050 % or less, Si: 2.0 % to 6.0 %, Mn: 1.0 % to 3.0 %, P: 0.20 % or less, S: 0.0050 % or less, N: 0.0050 % or less, and Al: 0.0050 % or less, with the balance being Fe and inevitable impurities, in which Si-Mn nitrides having an average diameter of 50 nm to 500 nm has a number density of 1/µm3 or less.