Metallographic Phase Classification for Fast Property Prediction

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Solution Overview

Problem

Existing methods for quantitatively evaluating the metallographic structure of metallic materials, such as steel plates, are prone to large errors due to operator variability and require significant time, making it difficult to accurately link material properties to the structure.

Innovation Solution

A method and device that utilize image preprocessing, feature value calculation, and machine learning to classify and predict the phase of metallographic structures, optimizing luminance levels for accurate phase classification and enabling efficient prediction of material properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual color-coding method is used to evaluate phase fraction, then operator can identify different phases, but large error occurs among operators and significantly long time is needed

Engineering Contradiction:
Improvephase fraction measurement accuracyVSAvoidanalysis time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the manual mechanical color-coding process with an automated image processing system using luminance value binarization. The computer automatically converts grayscale images to binary images by comparing pixel luminance values against a threshold, eliminating manual intervention and enabling rapid, consistent phase fraction measurement without operator variability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement parameter from subjective color perception to objective luminance value thresholding. By converting the continuous grayscale luminance values into binary categories (phase present/absent) based on a determined threshold value, the system achieves both speed and consistency in phase fraction evaluation.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If luminance value binarization method is used to evaluate metallographic structure, then analysis time is reduced significantly, but large error occurs when difference in luminance value for each phase is not clear

Engineering Contradiction:
Improveanalysis speedVSAvoidphase classification accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent employs feedback through iterative threshold optimization. The system determines the luminance value threshold by analyzing the histogram distribution of luminance values in the metallographic image, using the feedback from the image data itself to establish an optimal threshold that maximizes phase classification accuracy while maintaining fast processing speed.

Inventive Principle:
Principle #23Feedback

3Reliability

If repeated observation by optical microscope is conducted to control metallographic structure, then material properties can be evaluated, but significantly long time is needed for quantitative evaluation

Engineering Contradiction:
Improvematerial property evaluation reliabilityVSAvoidevaluation time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces repeated manual microscopic observations with a single automated image processing operation. By substituting the mechanical process of multiple manual measurements with an automated computer-based luminance thresholding system, the patent achieves reliable material property evaluation in a fraction of the time required for traditional repeated observations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP4099012B1Metallographic structure phase classification method, metallographic structure phase classification device, metallographic structure phase learning method, metallographic structure phase learning device, metallic material property prediction method, and metallic material property prediction device
Publication Date: 2026.03.04 JFE STEEL CORP
  • EP4099012B1 patent drawingFigure 1~2
  • EP4099012B1 patent drawingFigure 3
  • EP4099012B1 patent drawingFigure 4~5

AI summary

A metallographic structure phase classification method includes a feature value calculation step of calculating one or more feature values for each pixel of an image captured of a metallographic structure of a metallic material, and a phase classification step of classifying the phase of the metallographic structure in the image by inputting each feature value calculated in the feature value calculation step to a learning-completed model subjected to learning using feature values to which one of labels of a plurality of phases of the metallographic structure are allocated as inputs and the labels of the phases as outputs and acquiring the label of the phase of a pixel corresponding to the input feature value.