GB/T 15749-1995 Quantitative metallographic manual determination method
Some standard content:
ICS77.040.30bzxz.net
National Standard of the People's Republic of China
GB/T 15749—1995
Manual measuring method in quantitative metallography
Issued on November 20, 1995
Implemented on August 1, 1996
Issued by the State Bureau of Technical Supervision
National Standard of the People's Republic of China
Manual measuring method in quantitative metallography
Manual measuring method in quantitative metallopraphySubject content and scope of application
GE/T 15749-1995
This standard specifies the basic principles, measuring tools and determination methods for determining the volume percentage of phases in microstructures by the grid point method, grid intercept method and microscope eyepiece scale. This standard is applicable to the determination of the content (volume percentage) of various alloy phases in microstructures with morphologies similar to equiaxed, strip-shaped and branched shapes.
2 Reference standards
Method for determining the ferrite content of chromium-nickel austenitic stainless steel welds GB1954
CB1196Metallurgical determination method for phase content of copper alloys for ship propellers 3 Terminology
3. 1 Determination of metallographic structure
A method for inferring the metallographic structure content in three-dimensional space from the two-dimensional parameters measured from the metallographic grinding surface. 3.2 Grid point method
A method for measuring phases using grid nodes and obtaining their volume content based on the parameters of the points. 3.3 Grid intercept method
A method for measuring phases using grid line segments and obtaining their volume content based on the line segment parameters. 3.4 Microscope eyepiece scale measurement method
Use a microscope eyepiece with a scale to directly measure the phase in the microscope and obtain its volume content based on the line segment parameters. 4 Basic principle
Through the quantities of geometric parameters such as points, lines, and surfaces in a two-dimensional plane, according to the mutual relationship between the percentages of points, lines, surfaces, and volumes in formula (1), the three-dimensional spatial value of the phase to be measured in the microstructure is deduced. The interchange equation is:
Pr= Li = As=Vv
Percentage of the intersection point to be measured;
In the formula, P.—
LI. Percentage of the intercept line of the phase to be measured;
A.——Percentage of the area of the phase to be measured;
Vv——Percentage of the volume of the phase to be measured.
The mutual relationship in formula (1) is shown in Figure 1.
Approved by the State Administration of Technology on November 20, 1995 (1)
Verified on August 1, 1996
5 Measurement method
5.1 General
GB/T15749—1995
Figure 1=Schematic diagram of A, V
5.1.1 The object to be measured in the metallographic grinding surface should be clearly displayed. 5.1.2 According to the morphological characteristics of the phase, the grid point method, grid line method or microscope self-mirror scale measurement method should be reasonably selected. 5.1.3 When selecting the grid measurement method (point method or line method), the spacing of the measurement grid should be close to the distance between the phases to be measured. 5.1.4 When measuring, a representative field of view in the sample should be selected. The number of measurement fields should be faster than the uniformity of the measured phase, generally not less than three.
5.1.5 The effective numbers of measurement and calculation should be carefully kept to one decimal place. 5.1.6 The identification of the morphological type of the phase to be measured is shown in Figures 6 to 17. 5.2 Engraving tools
5.2.1 The measuring tools used in the grid point counting method and the grid cutting method can be prepared by themselves using transparent films according to the three different specifications listed in Table 1, see Figures 2, 3 and 4. Used for measuring pictures or gross glass images, Table I
Grid total segment length L+mtn
Total number of grid points Fe-number of points
10×10
Figure 26mm×émm measurement grid
15×15
GB/T 15749—1995
Figure 310mm×10mm measurement grid
Figure 415mm×15mml measurement grid
LLAALLLAL
GB/T 15749—1995
5.2.2 Microscope eyepiece scale measurement method A rotatable microscope eyepiece with scale must be available. The standard with eyepiece scale is shown in Figure 5. Figure 5200×
0\ Microscope eyepiece scale measurement field of view
5.3 Grid point method
5.3.1 The grid point method is only applicable to the determination of equiaxed phases. 5.3.2 Select a suitable measurement grid according to 5.1.3, cover it on the image to be measured, and count the number of grid points falling in the measured phase. The grid points on the boundary of the measured phase are counted as 1/2 points. 5.3.3 The percentage of grid points is calculated according to formula (2). The number calculated according to formula (1) is the volume percentage of the measured phase. P=
Where: P——the percentage of intersection points of the measured phase, %:——the number of measurement grid points of the measured phase;
m——the total number of grid points of the measurement grid.
5.4 Grid Intercept Method
5.4.1 The grid intercept method is applicable to the measurement of equiaxed, strip-shaped, and branch-shaped phases. 5.4.2 The selection of the magnification factor of the microscope should control the minimum intercept of the phase to be measured to be no less than 1mm. (2)
5.4.3 Select a suitable measurement grid according to the provisions of 5.1.3, cover it on the image to be measured, and measure the length of the line segment of the phase to be measured. When the measured line segment coincides with the boundary of the phase to be measured, the length of the overlapping line segment is calculated as 1/2. 5.4.4 The line segment percentage is calculated according to formula (3). The number calculated according to formula (1) is the volume percentage of the phase to be measured. L,
Where: - line percentage of the phase to be measured, %; 1-line segment length of the phase to be measured. mm
f Total line segment length of the grid. m.
5.5 Microscope scale measurement method
5.5.1 The microscope eyepiece scale measurement method is applicable to the measurement of equiaxed, strip-shaped, and branched phases specified in this standard. 5.5.2 The magnification of the microscope should be selected so that the minimum intercept of the phase to be measured is not less than the minimum scale of the measuring tool. 5.5.3 Select an eyepiece with a scale to measure directly in the field of view. 3
5.5.4 When measuring a phase with an approximately equiaxed shape, measure the length (scale) of the line segment intercepted by the phase to be measured at four angles (approximately 0°, 45°, 90°, and 135°). GB/T 15749—1995
When the measured line segment coincides with the boundary of the phase to be measured, the coincident line segment is calculated as 1/2. 5.5.5 The percentage of the line segment is calculated according to formula (4). The number obtained by cutting according to formula (1) is the volume percentage of the phase to be measured. (L+L+L+Lu/4.100%
Wherein?
Lu,ir,Lo, Liy-
intercepted percentage of the phase to be measured, %;
represents the length of the line segment intercepted by the phase to be measured at 0°.45°, 90°, and 135°, grid: the total length of the measured line segment in the eyepiece, grid.
5.5.6 When measuring the phase in the form of strips or branches, eight angles should be measured, namely, approximately 0°, 22.5°, 45°, 67.590°, 112.5°135°, and 157.5°. Measure the length of the line intercepted by the phase to be measured at each angle. When the edge of the phase to be measured coincides with the measuring line segment, the overlapping line segment is 1/2 Calculation.
5.5.7: The percentage of the line segment is calculated using formula (5). The value calculated using formula (1) is the volume percentage of the phase to be measured (Cg+lar+LrtLnr+Ln+Lum++Lg+Lmp)/8, 100%L
Where; -
Intercept percentage of the phase to be measured, %!
ILr. Le2. st, LasI-rs*,Lgo* Litz-s*, Lys*, List. sLa Total length of the measured line segment in the eyepiece, grid.
5.6 Measurement Example
For measurement examples, see Appendix A (reference).
6 Morphological Examination Figure
6.1 Approximately Equiaxed
Approximately equiaxed microstructures are shown in Figures 6 to 1z. Figure 6200×
Spheroidal Graphite in Spheroidal Cast Iron
(5)
represents the measurement line segments at approximately 0°, 22.5°, 45°, 67.5% 90°, 112.5°135°, 157.The length of the line segment cut by the phase to be tested at the 5° position is:
Figure 7500×
Middle phase of special lead bronze
Figure 8500×
Pearlite in normalized steel
Figure 10500
GB/T 15749--1995
(Austenite + Ferrite)Austenite in duplex stainless steelFigure 122000×(Oil mirror)
Figure 9400×
Middle phase of duplex titanium alloy
Figure 11100x
Middle phase of Sn-Sb bearing alloy
Small block distribution of ferrite in stainless steel6.2 Strip
Strip microscopic red weave see Figure 13~Figure 16,
6. 3· Branched
Figure 13500×
Strip-shaped pearlite in rolled steel
Figure 15500×
Strip-shaped stone mulberry in Dong cast iron
The microstructure of the technical shape is shown in Figure 17.
GB/T 15749—1995
(Martensite + Ferrite) Strip Ferrite in Duplex Stainless Steel Figure 162 000× (Oil Mirror)
Weaved Strip β Phase in Duplex Titanium Alloy Figure 172000× (Oil Mirror)
Branched Ferrite in Austenitic Stainless Steel Weld A1 Take α+β Brass as an Example
GB/T 15749—1995
Appendix A
Test Example
(Reference)
Figure A1 is α+β brass, in which the blocky α phase is the object to be tested. According to its approximately equiaxed morphological characteristics, the grid point method, grid line section method and microscope eyepiece scale measurement method are used for measurement. Figure A1500X
Grid method for measuring phase a in brass
A2 Grid point method
According to 5.1.3, select a 10mm×10mm measurement grid and cover it slightly on the image to be measured (Figure A1). Count the number of grid points falling on phase a, which is 29.5. Substitute it into formula (2) to obtain Pp(Pr × 100% =
Vya --Pr.. -
A3 Grid intercept method
× 100%-33.5%
According to 5.1.3, select a 10mm×10rmm Measuring grid, cover it on the image to be measured (Figure A1), measure the length of the line segment intercepted by the a phase to be 518nm, substitute it into formula (3), and calculate L.lel. Vvar-Lrn,-
A4 Microscope eyepiece scale measurement method
15%×100%-83%
Deep Use a microscope eyepiece with 100 scales to measure the length of the line segment intercepted by the α phase at angles of approximately 0°45°90°135° (grid number), and list them in Table A1. Use formula (4) to calculate the average 1 small r1:8
Measurement angle
Additional instructions:
Vyan = LL
GB/T 15749—1995
(L+ L-+Lg-+Lis-)/4
×100%
(36±32±33.5±30)/4×100%
10×100%=32.9%
This standard is proposed by China State Shipbuilding Corporation. This standard is approved by the National Technical Committee for Heat Treatment Standardization. 135
【Average）
This standard is drafted by the 725th Institute of the 7th Research Institute of China State Shipbuilding Corporation, Guangzhou Shipyard, and East China Institute of Marine Engineering. The main drafters of this standard are Wang Donglin, Tong Huirong, Song Fuchang, Sun Nai, and Lin Ling.
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.