Photographing condition determining method for metal structure, photographing method for metal structure, phase classification method for metal structure, photographing condition determining device for metal structure, photographing device for metal structure, phase classification device for metal structure, material property estimating method for metal material, and material property estimating device for metal material

Patent metadata

Field	Value
Publication number	US-12106466-B2
Application number	US-202117915126-A
Country	US
Kind code	B2
Filing date	Mar 8, 2021
Priority date	Mar 31, 2020
Publication date	Oct 1, 2024
Grant date	Oct 1, 2024

Abstract

A photographing condition determining method includes: photographing a part of a metal structure of a metal material subjected to predetermined sample preparation under a predetermined photographing condition; assigning, to pixels corresponding to one or a plurality of predetermined phases of the metal structure, labels of respective phases for a photographed image; calculating one or more feature values for a pixel to which a label of one of the assigned phases; classifying the phases of the metal structure of the image by inputting a calculated feature value to a model, which has been learned in advance using feature values assigned with labels of respective phases as input and labels of the respective phases as output, and acquiring a label of a phase of a pixel corresponding to the input feature value; and determining a photographing condition when other parts of the metal structure are photographed based on a classification result.

First claim

The invention claimed is:

1. A photographing condition determining method for photographing a metal structure of a metal material, the photographing condition determining method comprising:
a photographing step of photographing a part of the metal structure of the metal material having been subjected to predetermined sample preparation under a predetermined photographing condition;
a phase specification step of assigning, to pixels corresponding to one or a plurality of predetermined phases of the metal structure, labels of respective phases for an image photographed in the photographing step;
a feature value calculating step of calculating one or more feature values for a pixel to which a label of one of the phases has been assigned in the phase specification step;
a phase classification step of classifying the phases of the metal structure of the image by inputting a feature value calculated in the feature value calculating step to a model, which has been learned in advance using feature values assigned with labels of respective phases as input and labels of the respective phases as output, and acquiring a label of a phase of a pixel corresponding to the feature value that has been input; and
a photographing condition determining step of determining a photographing condition when other parts of the metal structure are photographed based on a classification result of the phase classification step.

2. The method according to claim 1 ,
wherein, in the photographing step, a part of the metal structure is photographed under a plurality of predetermined photographing conditions, and
in the photographing condition determining step, a photographing condition with which a classification accuracy of the phases in the phase classification step is the highest among the plurality of photographing conditions used in the photographing step is determined as a photographing condition for photographing the other parts of the metal structure.

3. The method according to claim 1 , wherein the photographing condition includes at least one of a contrast value, a brightness value, and an intensity of a light source.

4. The method according to claim 1 , further comprising, before the photographing step:
a polishing step of roughly polishing the metal material and then performing buffing using a polishing material of 0.05 μm to 2 μm; and
an etching step of etching the metal material using a nital solution prepared by mixing ethanol and nitric acid and has a nitric acid concentration of 0.5% to 8%.

5. A photographing method for a metal structure, wherein the other parts of the metal structure of the metal material are photographed under the photographing condition determined by the photographing condition determining method after the photographing condition determining method for a metal structure according to claim 1 .

6. A phase classification method for a metal structure, comprising the steps of: photographing the metal structure by the photographing method for a metal structure according to claim 5 ; and classifying phases of the metal structure.

7. A material property estimating method for a metal material for estimating a material property of the metal material, the material property estimating method comprising, after the method according to claim 6 :
a quantitative evaluation step of calculating a quantitative evaluation value of the metal structure by calculating a size, an area ratio, or a shape of each of the classified phases;
a data selection step of selecting data to be used for estimation of a material property of the metal material from the quantitative evaluation value and material properties of the metal material prepared in advance;
a model generating step of generating an estimation model for estimating a material property of the metal material using the data that has been selected; and
a material property estimating step of estimating a material property of the metal material using the estimation model that has been generated.

8. A photographing condition determining method for photographing a metal structure of a metal material, the photographing condition determining method comprising:
a photographing step of consecutively photographing a part of the metal structure having been subjected to predetermined sample preparation while a photographing condition is varied;
a feature value calculating step of calculating one or more feature values for images photographed in the photographing step;
a phase classification step of classifying phases of the metal structure of the image by inputting a feature value calculated in the feature value calculating step to a model, which has been learned in advance using feature values of pixels assigned with labels of one or a plurality of predetermined phases of the metal structure as input and labels of the respective phases as output, and acquiring a label of a phase of a pixel corresponding to the feature value that has been input; and
a photographing condition determining step of determining a photographing condition when other parts of the metal structure are photographed from among a plurality of photographing conditions used in the photographing step based on a classification result of the phase classification step.

9. The method according to claim 8 , wherein, in the photographing condition determining step, a photographing condition under which a classification accuracy of the phases in the phase classification step is a highest among the photographing conditions used in the photographing step is determined as a photographing condition for photographing the other parts of the metal structure.

10. The method according to claim 8 , wherein the photographing condition includes at least one of a contrast value, a brightness value, and an intensity of a light source.

11. The method according to claim 8 , further comprising, before the photographing step:
a polishing step of roughly polishing the metal material and then performing buffing using a polishing material of 0.05 μm to 2 μm; and
an etching step of etching the metal material using a nital solution which is prepared by mixing ethanol and nitric acid and has a nitric acid concentration of 0.5% to 8%.

12. A photographing method for a metal structure, wherein the other parts of the metal structure of the metal material are photographed under the photographing condition determined by the photographing condition determining method after the method according to claim 8 .

13. A phase classification method for a metal structure, comprising the steps of: photographing the metal structure by the method according to claim 12 ; and classifying phases of the metal structure.

14. A photographing condition determining device for photographing a metal structure of a metal material, the photographing condition determining device comprising:
a photographing unit that photographs a part of the metal structure of the metal material having been subjected to predetermined sample preparation under a predetermined photographing condition;
a phase specification unit that assigns, to pixels corresponding to one or a plurality of predetermined phases of the metal structure, labels of respective phases for an image photographed by the photographing unit;
a feature value calculating unit that calculates one or more feature values for a pixel to which a label of one of the phases has been assigned by the phase specification unit;
a phase classification unit that classifies the phases of the metal structure of the image by inputting a feature value calculated by the feature value calculating unit to a model, which has been learned in advance using feature val

Assignees

• Jfe Steel Corp

Inventors

• Kiyokane Naoya
• Obata Yoshie
• Ishikawa Shin
• Yamashita Takako
• Nishiyama Takeshi

Classifications

• G06T2207/30168

  Image quality inspection · CPC title

• G06T2207/30136

  Metal · CPC title

• G06T2207/20084

  Artificial neural networks [ANN] · CPC title

• G06T2207/10056

  Microscopic image · CPC title

• G01N1/32

  Polishing; Etching · CPC title