CN115684235A - A method for measuring the diameter of spherical inclusions in steel samples - Google Patents

Abstract

The application discloses a method for measuring the diameter of spherical inclusions in a steel sample, comprising the following steps: polishing the measured surface of the steel sample so that the measured surface is a polished surface; selecting spherical inclusions in the polished surface of the steel sample Slice the spherical inclusions along the direction perpendicular to the polishing surface to obtain the images of the series of thin slices of the spherical inclusions; from the images of the series of thin slices, select the thin slices with the longest chord of the semicircle; Draw any two straight line segments D1 and D2 that are parallel to the chord and do not overlap on the thin slice image, and the line segment connecting the center points of the straight line segment D1 and segment D2 is Δd; Substitute the measured values of D1 and D2 and Δd into the formula to calculate the spherical shape The diameter of the inclusion. The measurement method is simple and efficient, the result is accurate, and there is no special requirement for sample preparation, nor for test personnel, and it can be calculated with simple training, which makes up for the current inability to accurately obtain the actual diameter of spherical inclusions.

Description

A method for measuring the diameter of spherical inclusions in steel samples

technical field

The application relates to the technical field of metallurgy, in particular to a method for measuring the diameter of spherical inclusions in steel samples.

Background technique

In steel samples, the existence of spherical inclusions has a great impact on the properties of steel. At present, the grade is mainly evaluated by metallographic method, and the diameter is an important index for evaluating the grade of spherical inclusions.

In the prior art, the method for measuring the diameter of spherical inclusions in iron and steel samples is to prepare the test surface of the sample by a standard metallographic sample preparation method to obtain a polished surface, and then observe the shape of the inclusions through an optical microscope or a scanning electron microscope. appearance, and test its diameter. The diameter measured by this method is the cross-sectional diameter of the ball corresponding to the spherical inclusion, not the actual diameter of the ball. Different degrees of grinding and polishing during sample preparation will lead to great differences in the cross-sectional diameter of the same ball, and the results are unreliable.

Therefore, it is necessary to design a measurement method that can accurately obtain the actual diameter of spherical inclusions in steel samples.

application content

Therefore, the technical problem to be solved in this application is to overcome the defect that the existing technology cannot accurately measure the diameter of spherical inclusions in steel samples, so as to provide a measurement method that can accurately measure the diameter of spherical inclusions in steel samples.

In order to solve the problems of the technologies described above, the technical scheme of the present application is as follows:

A method for measuring the diameter of spherical inclusions in a steel sample, comprising:

S1, polishing the measured surface of the steel sample, so that the measured surface of the steel sample is a polished surface;

S2. Select spherical inclusions on the polished surface of the steel sample, slice the spherical inclusions in a series along a direction perpendicular to the polished surface, and obtain images of a series of thin slices of the spherical inclusions perpendicular to the polished surface;

S3. Selecting a thin slice of the semicircle with the longest chord from the images of the series thin slices of spherical inclusions;

S4. Draw any two straight line segments D1 and D2 that are parallel to the chord and do not overlap on a slice of the semicircle with the longest chord. The line segment between the center point of segment D1 and the center point of straight segment D2 is Δd, and the values of D1 and D2 and Δd are measured;

S5. Substituting the measured values of D1 and D2 and Δd into the formula to calculate the diameter of the spherical inclusion.

Further, before the step of S1, the following steps are also included:

Use wire cutting to cut the steel piece to be tested into thin rectangular steel sample slices;

Grinding and polishing the six faces of the steel sample sheet until there are no cutting marks on the surface of the steel sample sheet;

Ultrasonic cleaning is performed on the ground and polished steel sample sheet to obtain the steel sample in step S1.

Further, in the step S1, the measured surface of the steel sample is the side with the largest surface area of the steel sample.

Further, in the step S2, the iron and steel sample is loaded into a double-beam scanning electron microscope, and the spherical inclusion with the largest diameter observed on the polished surface of the iron and steel sample is selected as the selected spherical inclusion.

Further, before the step of serially slicing the spherical inclusions along the direction perpendicular to the polishing surface, the surface of the spherical inclusions is sprayed with a carbon layer with a predetermined thickness, and the length and width of the carbon layer cover the spherical inclusions.

Further, in the step of S2, when the spherical inclusions are sliced in series along the direction perpendicular to the polishing surface, the thickness of each slice is the same.

Further, in the step S2, a camera is used to obtain images of a series of thin slices of spherical inclusions perpendicular to the direction of the polishing surface.

Further, in the step of S5, the diameter of the spherical inclusion

The technical solution of the present application has the following advantages:

1. The method for measuring the diameter of spherical inclusions in iron and steel samples provided by this application is to slice the spherical inclusions on the polished surface of the steel sample in a series of slices along the direction perpendicular to the polished surface, and obtain images of the series of thin slices of spherical inclusions, Select a slice of the semicircle with the longest chord from the images of the series of slices as the actual calculated diameter slice, and draw any two straight line segments D1 and D2 that are parallel to the chord and do not overlap on the slice of the semicircle with the longest chord , and the line segment Δd of the center point of the straight line segment D1 and the center point of the straight line segment D2, the actual diameter of the spherical inclusion can be calculated through the measured values of D1, D2 and Δd. This measurement method is simple and efficient, and the result is accurate. There is no special requirement for the sample, and there is no special requirement for the testers, and it can be calculated with simple training, which makes up for the current inability to accurately obtain the actual diameter of spherical inclusions.

Description of drawings

In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the specific embodiments or prior art. Obviously, the accompanying drawings in the following description The drawings are some implementations of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic diagram of calculating the actual diameter of spherical inclusions in the embodiment of the present application;

Figure 2 is a schematic diagram of a series of slices in the embodiment of the present application;

Fig. 3 is a slice image of the semicircle with the longest chord in the embodiment of the present application.

Detailed ways

The technical solutions of the present application will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are some of the embodiments of the present application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, use a specific orientation construction and operation, therefore should not be construed as limiting the application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and should not be construed as indicating or implying relative importance.

In the description of this application, it should be noted that unless otherwise specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application in specific situations.

A method for measuring the diameter of spherical inclusions in steel samples as shown in Figure 1-3, including the following steps:

Step S1 , polishing the measured surface of the steel sample, so that the measured surface of the steel sample is a polished surface.

Specifically, the steel sample is prepared according to the conventional metallographic sample preparation method. The steel sample is rectangular, and the measured surface of the steel sample is generally the side with the largest surface area of the steel sample. The conventional metallographic sample preparation method includes the following steps: firstly cut the steel piece to be tested into a sheet-like rectangular steel sample sheet by wire cutting; then grind and polish the six sides of the steel sample sheet until the surface of the steel sample sheet is not cut traces; finally, ultrasonic cleaning is performed on the polished and polished steel sample sheet to obtain the steel sample in the S1 step.

Step S2, selecting spherical inclusions on the polished surface of the steel sample, performing a series of slices of the spherical inclusions along a direction perpendicular to the polished surface, and obtaining images of a series of thin slices of the spherical inclusions perpendicular to the polished surface.

Specifically, a steel sample is loaded into a double-beam scanning electron microscope, and the spherical inclusion with the largest diameter observed in the polished surface of the steel sample is selected as the spherical inclusion. In fact, there may be one or more spherical inclusions observed in the polished surface of the steel sample, and the size of the multiple spherical inclusions will be different. The spherical inclusion with the largest diameter is used as the selected spherical inclusion. Spherical inclusions can be graded more accurately.

Before the step of serially slicing the spherical inclusions along the direction perpendicular to the polished surface, the surface of the spherical inclusions can also be sprayed with a carbon layer of predetermined thickness, the length and width of the carbon layer covering the spherical inclusions; for example, 0.5 μm thick carbon layer. The carbon layer can reduce the reflection of the polished surface of the steel sample, and form a clear boundary line between light and dark with the part where the carbon layer is not laid, so as to facilitate the observation of the arc profile of the spherical inclusion.

Specifically, when performing a series of slices on the spherical inclusions, the thickness of each slice is the same; after slicing, a camera is used to obtain images of the series of thin slices of the spherical inclusions.

Step S3, from the images of the series of thin slices of the spherical inclusions, a thin slice of the semicircle with the longest chord is selected.

Step S4. Draw any two straight line segments D1 and D2 that are parallel to the chord and do not overlap on a thin slice image of the semicircle with the longest chord. The two ends of the straight line segment D1 and the straight line segment D2 terminate at the edge of the arc respectively The line segment connecting the center point of the straight line segment D1 and the center point of the straight line segment D2 is Δd, and the values of D1 and D2 and Δd are measured.

Step S5, substituting the measured values of D1 and D2 and Δd into the formula to calculate the diameter of the spherical inclusion.

From the right triangle formula we know:

Formula 1)

Formula (2)

Formula (1)-(2), can calculate the formula (3)

Bringing the result of formula (3) into formula (1), R can be calculated:

The actual diameter of the ball is:

(4)

Bring the measured values of D1, D2 and Δd into formula (4) to obtain the actual diameter D of the ball.

This method of measuring the diameter of spherical inclusions in steel samples involves making serial slices of spherical inclusions on the polished surface of steel samples along the direction perpendicular to the polished surface, and obtaining images of a series of thin slices of spherical inclusions, from the series of thin slices Select a thin slice of the semicircle with the longest chord from the image as the actual calculated diameter slice, draw any two straight line segments D1 and D2 that are parallel to the chord and do not overlap, and a straight line on the thin slice image of the semicircle with the longest chord The line segment Δd between the center point of segment D1 and the center point of straight segment D2 can calculate the actual diameter of spherical inclusions through the measured values of D1, D2 and Δd. This measurement method is simple and efficient, and the result is accurate. There are no special requirements for testers, and it can be calculated with simple training, which makes up for the current inability to accurately obtain the actual diameter of spherical inclusions.

In the following, the sample of the ship plate steel weld zone is selected as the object of the embodiment, and the content of the invention is further elaborated.

1. Cut the sample into thin slices of 10mm×20mm×2mm (length×width×thickness) by wire cutting, grind and polish the six sides of the sample with 800-mesh sandpaper until there are no wire cutting marks, and put it into alcohol for ultrasonic cleaning clean;

2. The sample preparation surface is the surface of 10mm×20mm. After the sample is hot-mounted, the sample is prepared according to the conventional metallographic method until the surface is polished, and the small square piece is taken out;

3. Put the sample into the double-beam scanning electron microscope, find the spherical inclusion with the largest diameter in the measured surface, spray a 0.5μm thick carbon layer on the surface of the spherical inclusion, and the length and width of the carbon layer are based on covering the spherical inclusion ;

4. Set the thickness of the single slice, slice the spherical inclusions and take pictures;

5. Find the photo with the longest chord in the spherical inclusion series slice photos, as shown in Figure 3, draw any two non-overlapping straight line segments D1, D2 and the center of the straight line segment D1 that are parallel to the chord The line Δd between the point and the center point of the straight line segment D2 is measured as D1=9.912 μm, D2=7.392 μm, Δd=1.092 μm;

计算出球形夹杂物的实际直径约为13.315μm(四舍五入)。6. Bring in the formula

The actual diameter of spherical inclusions is calculated to be about 13.315 μm (rounded).

Apparently, the above-mentioned embodiments are only examples for clear description, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. However, the obvious changes or changes derived therefrom are still within the protection scope of the invention of the present application.

Claims (8)

1. A method for measuring the diameter of spherical clamp impurities in a steel sample is characterized by comprising the following steps:

s1, polishing the measured surface of a steel sample to enable the measured surface of the steel sample to be a polished surface;

s2, selecting spherical inclusions in the polished surface of the steel sample, and carrying out serial slicing on the spherical inclusions along the direction vertical to the polished surface to obtain serial slice images of the spherical inclusions vertical to the polished surface;

s3, screening a sheet of a semicircle with the longest chord from the images of the series of sheets of the spherical inclusions;

s4, drawing any two straight line segments D1 and D2 which are parallel to the chord and are not coincident on a sheet of the semicircle with the longest chord, respectively terminating two ends of each of the straight line segments D1 and D2 at the edge of the circular arc, respectively, and measuring the numerical values of D1, D2 and delta D, wherein the line segment connecting the central point of the straight line segment D1 and the central point of the straight line segment D2 is delta D;

and S5, substituting the measured numerical values of D1, D2 and delta D into a formula, and calculating to obtain the diameter of the spherical inclusion.

2. The method for measuring the diameter of the spherical inclusions in the steel sample according to claim 1, wherein the step of S1 is preceded by the steps of:

cutting a steel piece to be detected into a sheet-shaped rectangular steel sample sheet by adopting linear cutting;

grinding and polishing six surfaces of the steel sample slice until the surface of the steel sample slice has no cutting trace;

and carrying out ultrasonic cleaning on the polished steel sample slice to obtain the steel sample in the step S1.

3. The method for measuring the diameter of spherical inclusions in the steel sample according to claim 1, wherein the measured surface of the steel sample is the side surface having the largest surface area of the steel sample in the step S1.

4. The method for measuring the diameter of spherical inclusions in a steel sample according to claim 1, wherein in the step of S2, the steel sample is loaded into a dual-beam scanning electron microscope, and spherical inclusions with the largest diameter observed in a polished surface of the steel sample are selected as the spherical inclusions.

5. The method for measuring the diameter of spherical inclusions in a steel sample according to claim 4, wherein in the step of S2, a carbon layer is sprayed on the surface of the spherical inclusions with a predetermined thickness, and the length and width of the carbon layer covers the spherical inclusions, before the step of slicing the spherical inclusions in a direction perpendicular to a polished surface.

6. The method for measuring the diameter of the spherical impurities in the steel sample according to claim 1, wherein in the step of S2, when the spherical impurities are sliced in series in a direction perpendicular to the polishing surface, the thickness of each slice is the same.

7. The method for measuring the diameter of spherical inclusions in a steel sample according to claim 1, wherein in the step of S2, a camera is used to obtain images of a series of flakes of spherical inclusions in a direction perpendicular to a polished surface.

8. The method for measuring the diameter of spherical inclusions in a steel sample according to claim 1, wherein in the step of S5, the diameter of the spherical inclusions

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