Non-Oriented Electrical Steel Composition for Precise Punching
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Solution Overview
Problem
Existing non-oriented electrical steel sheets face challenges in maintaining precise punching dimensional accuracy, particularly in the coil width direction, when high alloying is used to reduce iron loss, leading to variations in dimensions during multiple punchings, especially for wider coils.
Innovation Solution
A non-oriented electrical steel sheet with specific chemical composition and controlled finish annealing conditions, including temperature rising, soaking, and cooling rates, along with insulating coating drying and tensile stress, to achieve low iron loss and improved punching dimensional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If high alloying is performed to reduce iron loss, then iron loss is reduced, but punching dimensional accuracy deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters (Si: 2.00-4.50%, Mn: 0.01-5.00%, Al: 0.03-5.00%) and processing parameters (temperature rising rate, soaking temperature, soaking time, cooling rate) to achieve both low iron loss and high punching dimensional accuracy. This resolves the contradiction by optimizing the parameter ranges to balance magnetic properties and mechanical properties.
Solution Approach 2:
The patent uses composite material principles by creating a multi-element alloy system (Fe-Si-Mn-Al) where each element contributes specific properties. Si increases electrical resistance to reduce eddy current loss, while Mn and Al control mechanical properties and phase transformation behavior. This composite approach allows simultaneous achievement of low iron loss and good punching accuracy.
2Strength
If high alloying is performed to improve strength, then strength is improved, but punching dimensional accuracy deteriorates
Solution Approach 1:
The patent controls the strength level by adjusting alloying parameters (Si, Mn, Al content) and heat treatment parameters (soaking temperature, cooling rate). By optimizing these parameters, the steel achieves sufficient strength while maintaining ductility and dimensional stability during punching operations.
Solution Approach 2:
The patent utilizes dynamic phase transformation during cooling (controlled by cooling rate parameters) to achieve desired mechanical properties. The phase transformation dynamics allow the material to develop appropriate strength and ductility balance, ensuring good punching performance without excessive strength that would cause dimensional variation.
3Productivity
If multiple punchings are performed on steel sheets, then production efficiency is improved, but punching dimensional accuracy deteriorates due to accumulation of dimensional variations
Solution Approach 1:
The patent applies preliminary action by performing finish annealing and insulating coating formation before punching operations. These preliminary treatments stabilize the steel sheet dimensions and reduce anisotropy, ensuring that subsequent multiple punching operations maintain consistent dimensional accuracy without accumulation of variations.
Solution Approach 2:
The patent implements feedback control by monitoring and controlling the relationship between yield stress and sheet thickness, and by controlling the uniform elongation anisotropy through process parameters. This feedback mechanism ensures that dimensional variations are corrected and maintained within acceptable ranges even after multiple punching operations.
4Productivity
If wide coil steel sheets are used, then productivity is improved, but punching dimensional accuracy deteriorates in the coil width direction
Solution Approach 1:
The patent controls dimensional accuracy in the coil width direction by adjusting the cooling rate parameter and uniform elongation control during rolling. These parameter changes ensure uniform dimensional properties across the entire coil width, maintaining punching accuracy even for wide coils that improve 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 solution results in a non-oriented electrical steel sheet with a standard deviation of punching dimension ratio within 0.010 or less and iron loss of 2.50 W/kg or less, ensuring consistent dimensional accuracy and reduced iron loss.
Implementation Method 1
a finish annealing step of performing finish annealing on the cold-rolled steel sheet to obtain a finish-annealed steel sheet
Implementation Method 2
when an average temperature rising rate of the steel sheet in a temperature range from 300° C. to 700° C. is represented by Vh (° C./sec), the soaking temperature of the steel sheet is represented by Tf (° C.), the soaking time of the steel sheet is represented by tf (sec), and the average cooling rate of the steel sheet in a temperature range from 700° C. to 300° C. is represented by Vc (° C./sec)
Implementation Method 3
when the insulating coating is performed in the insulating coating forming step, a drying temperature Tc (° C.) is 250 to 500° C.
Data Source
AI summary
A non-oriented electrical steel sheet includes, by mass %, C: 0.005% or less, Si: 2.00% or more and 4.50% or less, Mn: 0.01% or more and 5.00% or less, Al: 0.03% or more and 5.00% or less, total SE of one kind or two or more selected from the group consisting of S, Se, and Te: more than 0% and 0.005% or less, N: more than 0% and 0.005% or less, and P: more than 0% and 1.000% or less, in which a remainder includes Fe and impurities and Expression (1) and Expression (2) are satisfied, the standard deviation of a ratio LRD/LTD of a length LRD in a rolling direction to a length LTD in a width direction of a circular hole after punching the steel sheet using a substantially circular die is 0.010 or less, and an iron loss W15/50 is 2.50 W/kg or less.(Si+Mn+Al)≥4.5%Expression (1)Al/3≤MnExpression (2)