Non-Oriented Electrical Steel Sheet for Mn Diffusion Control
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Solution Overview
Problem
The existing non-oriented electrical steel sheets face challenges in maintaining the adhesiveness of the insulating coating film due to Mn diffusion during stress relief annealing, which affects the magnetic properties and efficiency of motors.
Innovation Solution
The non-oriented electrical steel sheet is formulated with specific ranges of Sn, Sb, and Mn, and a shot ball projection method is used to adjust the scale removal process, preventing Mn diffusion into the insulating coating film during stress relief annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If stress relief annealing is performed to remove stress from the steel sheet, then stress is removed, but Mn diffuses into the insulating coating film causing decreased adhesiveness
Solution Approach 1:
The patent applies preliminary action by adjusting the Al content to 0.1-1.3% before stress relief annealing to control Mn diffusion. This pre-adjustment of composition prevents excessive Mn migration into the coating during subsequent annealing, thereby maintaining coating adhesiveness while still achieving stress removal
Solution Approach 2:
The patent changes chemical composition parameters by limiting Al to 0.1-1.3% and Mn to 0.3-2.0%, and controlling the Al/Mn ratio. These parameter adjustments modify the diffusion behavior of Mn during stress relief annealing, preventing harmful Mn migration into the insulating coating while maintaining the necessary stress relief effect
2Reliability
If Sb and Sn are added to suppress Mn diffusion, then Mn diffusion is partially suppressed, but the effect is insufficient and coating adhesiveness still decreases
Solution Approach 1:
The patent extracts the reliance on Sn and Sb additives by minimizing their dependence. Instead of depending on these elements to suppress Mn diffusion, the patent focuses on optimizing Al content and controlling the Al/Mn ratio, thereby reducing Mn diffusion through compositional control rather than additive-based suppression
Solution Approach 2:
The patent changes the approach from using Sn/Sb additives to controlling base element ratios. By adjusting Al to 0.1-1.3% and Mn to 0.3-2.0% with controlled Al/Mn ratios, the patent modifies the fundamental diffusion dynamics without relying on supplemental elements, achieving more effective Mn diffusion suppression
3Object-generated harmful factors
If a surface oxide layer is formed to suppress Mn diffusion, then some protection is provided, but the binding force between coating and base material is weakened
Solution Approach 1:
The patent changes the strategy from forming surface oxide layers to controlling bulk composition. By adjusting Al to 0.1-1.3% and Mn to 0.3-2.0% with appropriate Al/Mn ratios, the patent prevents excessive Mn diffusion from the bulk, eliminating the need for protective oxide layers and preserving direct coating-to-base-material bonding strength
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 approach enhances the adhesiveness of the insulating coating film, leading to improved magnetic properties and reduced iron loss in motors, thereby increasing their efficiency and performance.
Implementation Method 1
a Mn component in the steel sheet diffuses into an insulating coating film
Implementation Method 2
Suppression of diffusion of Mn through formation of a surface oxide layer and a surface segregation element layer
Implementation Method 3
increasing a shot ball projection amount when removing scale
Data Source
AI summary
A non-oriented electrical steel sheet according to one embodiment of the present invention comprises a steel sheet base material and an insulation film positioned on the steel sheet base material, satisfies the following formula 2 before stress relief annealing, and satisfies the following formula 3 after stress relief annealing, the steel sheet base material comprising, by wt %, 2.0-6.5% of Si, 0.1-1.3% of Al, 0.3-2.0% of Mn, 0.03% or less of Sn (excluding 0%), 0.02% or less of Sb (excluding 0%) and the balance of Fe and other inevitable impurities and satisfying the following formula 1.0.03≥[Sn]+[Sb]≥0.005[Formula 1]0.1≥[Mn film]/[Mn50][Formula 2]10≥[Mn film]/[Mn50]≥1[Formula 3](In formula 1 to formula 3, [Sn] and [Sb] represent the amounts of Sn and Sb, respectively, [Mn film] represents the average amount (wt %) of Mn in the insulation film, and [Mn50] represents the amount (wt %) of Mn at a depth of 50 μm from the interface between the steel sheet base material and the insulation film toward the inside of the steel sheet base material.)