Carburization Detection via Magnetic Strength Correlation

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Solution Overview

Problem

Existing methods for sensing carburization in steel materials, such as cracking tubes, face accuracy issues due to varying electromagnetic properties of base metals, leading to inconsistent calibration curves and reduced accuracy in determining carburization thresholds during electromagnetic testing.

Innovation Solution

A method involving the use of a reference material with equivalent electromagnetic properties, where multiple magnetic materials with different strengths are attached to determine correlations between magnetic strength and electromagnetic test output values, allowing for the calculation of carburized depth and electromagnetic test output value thresholds, thereby improving the accuracy of carburization sensing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If calibration curves are calculated using carburized materials collected from multiple cracking tubes with different histories, then the possibility to collect carburized materials with different carburized depths increases, but the electromagnetic properties of the base metal vary leading to reduced measurement precision

Engineering Contradiction:
Improvevariety of carburized materialsVSAvoidaccuracy of carburization threshold determination
Core Design Contradiction:
Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent introduces magnetic strength as an intermediary parameter that correlates with both carburized depth and electromagnetic test output values. By measuring magnetic strength of carburized materials and establishing its correlation with electromagnetic test results, the method enables accurate threshold determination without being affected by variations in base metal electromagnetic properties. This intermediary measurement approach resolves the contradiction by providing a stable reference that is independent of base metal variability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the measurement parameter from direct electromagnetic test output comparison to magnetic strength measurement. By using magnetic strength (measured by ferrite meter) as the primary parameter and correlating it with electromagnetic test values, the method transforms the measurement approach to one that is insensitive to base metal electromagnetic property variations, thereby maintaining measurement precision while allowing diverse carburized materials to be used for calibration.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If electromagnetic tests are performed on carburized materials with varying base metal properties, then the calibration process becomes more flexible, but the accuracy of threshold determination is reduced

Engineering Contradiction:
Improveflexibility in calibration processVSAvoidaccuracy of carburization threshold
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

Magnetic strength serves as an intermediary that decouples the calibration process from base metal electromagnetic property variations. The method measures magnetic strength of test pieces, correlates it with electromagnetic test output values, and uses this correlation to determine accurate thresholds regardless of base metal variability. This maintains flexibility in selecting diverse carburized materials while ensuring precision through the intermediary magnetic strength measurement.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the critical measurement parameter from electromagnetic test output values (which vary with base metal properties) to magnetic strength values (which are stable and correlate with carburized depth). This parameter transformation allows the calibration process to accommodate various carburized materials while maintaining consistent and accurate threshold determination across different base metal compositions.

Inventive Principle:
Principle #35Parameter changes

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 enables accurate determination of carburization thresholds, enhancing the sensing accuracy of carburization in steel materials by minimizing the impact of base metal electromagnetic properties on test results.

Implementation Method 1

an electromagnetic test such as an electromagnetic induction test is carried out on a cracking tube installed in a plant

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a magnetic strength of each magnetic material is measured, and based on the measured magnetic strength values and electromagnetic test output values of the each magnetic material, a correlation between the measured magnetic strength value and electromagnetic test output value is calculated

Methodology Applied
Scientific EffectMagnetic property measurement: Magnetism

Data Source

PatentEP2402744B1Carburization detection method
Publication Date: 2016.11.23 NIPPON STEEL & SUMITOMO METAL CORP
  • EP2402744B1 patent drawingFigure 1~2
  • EP2402744B1 patent drawingFigure 3~4
  • EP2402744B1 patent drawingFigure 5~6

AI summary

A carburization sensing method according to the present invention includes: a first procedure of attaching a magnetic material to a reference material which has equivalent electromagnetic properties to those of a test material and is not carburized, a second procedure of measuring magnetic strength of each magnetic material and to acquire an electromagnetic test output value for each magnetic material, a third procedure of calculating a correlation between the measured magnetic strength value and the electromagnetic test output value, a fourth procedure of measuring magnetic strengths on a plurality of carburized materials, a fifth procedure of calculating a correlation between a carburized depth and the measured magnetic strength value, a sixth procedure of determining a threshold value Th2 of the measured magnetic strength value corresponding to a threshold value Th1 of the carburized depth to be sensed, a seventh procedure of determining a threshold value Th3 of an electromagnetic test output value corresponding to the threshold value Th2 of the measured magnetic strength value, and an eighth procedure to sense whether carburization occurs or not in a test material based on the magnitude correlation between the electromagnetic test output value of the test material and the threshold value Th3 of the electromagnetic test output value.