Fe-Based Amorphous Alloy Strip Cost Reduction

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Solution Overview

Problem

The existing Fe-based amorphous alloy strips for transformer cores face challenges with high production costs due to the use of high purity iron sources, limited availability of low-grade iron sources, and difficulties in achieving low watt loss and high flux density simultaneously, while maintaining heat stability and workability.

Innovation Solution

Incorporating nitrogen (N) and optimizing the amounts of boron (B), silicon (Si), carbon (C), phosphorus (P), and other impurities in the alloy composition to enhance heat stability, amorphous phase forming ability, workability, and watt loss, while using low-grade iron sources to reduce costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high purity iron sources (electrolytic iron) are used to produce Fe-based amorphous alloy strip, then the magnetic properties and heat stability are improved, but the production cost increases significantly

Engineering Contradiction:
Improvemagnetic property stabilityVSAvoidproduction cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive high-purity electrolytic iron with cheaper low-grade iron sources containing impurities. By deliberately adding small amounts of impurity elements (P: 0.001-0.05 wt%, S: 0.001-0.03 wt%, Mn: 0.01-0.5 wt%, Si: 0.01-0.5 wt%) to controlled levels, the patent achieves acceptable magnetic properties without requiring costly high-purity raw materials, thus reducing production costs while maintaining functional performance

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the compositional parameters by defining specific impurity element content ranges rather than requiring near-zero impurity levels. By controlling impurity elements within specific ranges (total impurities ≤0.5 wt%), the patent transforms the approach from purity maximization to controlled composition optimization, enabling use of lower-cost iron sources while achieving stable magnetic properties

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If the flux density of amorphous alloy strip is increased by adding Co, then the saturated flux density improves, but the production cost increases due to expensive Co material

Engineering Contradiction:
Improvesaturated flux densityVSAvoidproduction cost
Core Design Contradiction:
Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent eliminates expensive Co from the alloy composition and instead uses low-grade iron sources with controlled impurity levels. The patent achieves adequate flux density (1.3-1.6 T) through optimized Fe-B-Si-C-P composition with B: 2-10 wt%, Si: 0.1-5 wt%, C: 0.1-2 wt%, avoiding the need for costly Co additions while maintaining functional performance at lower cost

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent extracts Co from the traditional Fe-B-Si-Co amorphous alloy composition. By removing this expensive element and compensating through optimized combinations of Fe, B, Si, C, and controlled impurity elements, the patent achieves the desired magnetic properties without Co, significantly reducing material costs

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of manufacture

If P is added to increase allowable amounts of S, Mn and other impurity elements, then the cost is reduced, but the heat stability and workability may be affected

Engineering Contradiction:
Improveraw material costVSAvoidheat stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent optimizes the P content within a specific range (0.001-0.05 wt%) to achieve the right balance. This controlled parameter approach allows P to facilitate the use of lower-grade iron sources with higher impurity tolerance while maintaining heat stability during annealing and operational temperature ranges, preventing unwanted phase transformations

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies the concept of local quality control by allowing higher impurity levels (S, Mn, Si) only within specific ranges that do not compromise overall performance. By locally tolerating certain impurities up to defined thresholds while controlling their total sum (≤0.5 wt%), the patent enables cost reduction through lower-grade materials while maintaining global product quality and heat stability

Inventive Principle:
Principle #3Local quality

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 enables the production of Fe-based amorphous alloy strips with improved flux density, heat stability, workability, and reduced watt loss, specifically achieving a stable watt loss of 0.10 W/kg or less, while maintaining the use of low-grade iron sources to lower production costs.

Implementation Method 1

superior in heat stability, amorphous phase forming ability, workability, and watt loss

Methodology Applied
Scientific EffectHeat stability:

Implementation Method 2

an amorphous alloy similar to liquid metal can be obtained

Methodology Applied
Scientific EffectAmorphous phase forming: Vitrification

Implementation Method 3

soft magnetic property watt loss W13/50 of a stable 0.10 W/kg or less

Methodology Applied
Scientific EffectWatt loss: Magnetic Hysteresis

Data Source

PatentUS7744703B2Fe-based amorphous alloy strip
Publication Date: 2010.06.29 NIPPON STEEL CORPORATION

AI summary

The present invention provides a Fe—B—Si system amorphous alloy thin strip excellent in high magnetic flux density, thermal stability, amorphous formability improved workability and low core loss. The present invention further provides a Fe—B—Si system amorphous alloy thin strip which has the reduced cost without using high purity iron resources such as an electrolytic iron as iron resources used in an amorphous alloy thin strip, and also has core loss less than 0.10 W/kg at W13/50 in soft magnetic property in alternating-current field. The Fe—B—Si system amorphous alloy thin strip according to the present invention contains an appropriate amounts of N, C, P to improve thermal stability, amorphous formability, workability (brittleness), and core loss without deteriolating magnetic flux density, and contains, in atomic %, B: 5-25%, Si: 1-30%, N: 0.001-0.2%, C: 0.003-10%, P: 0.001-0.2% and the balance being Fe and unavoidable impurities, and optionally contains Co or Ni substituted to less than 15% of the Fe amount, or Cr at less than 5% substituted to the Fe amount. Further, Mn: 0.15-0.5 mass %, S: 0.004-0.05 mass % can be included.