1. A small hole profile characteristic reduction method for eliminating tilting errors of a metallographic examination observation surface is characterized by comprising the following steps:

1) selecting a test board with parallel upper and lower surfaces, and preparing 3 collinear equidistant small holes on the test board by adopting the same processing technology;

2) appointing any side of the test board to be tested as a small hole inlet side and the other side as an outlet side, enabling a metallographic examination observation surface to pass through the 3 small holes, measuring the aperture of the inlet and the outlet of the small hole, and respectively calculating an average value;

3) cutting along the edge at one side of the 3 small holes, and inlaying and grinding according to a standard metallographic sample preparation process to enable the 3 small holes to be completely presented from the inlet to the outlet side of the whole side wall profile under metallographic examination;

4) measuring the contour widths of the inlet and outlet sides of the 3 small holes, and calculating the distance between the circle center of the inlet and outlet sides of each hole and the metallographic examination observation surface according to the average value in the step 2);

5) determining a reference plane formed by the metallographic examination observation surface and the central axis of the 3 small holes at the intersection point of the inlet and the outlet side according to the distance between the circle centers of the inlet and the outlet side in the step 4) and the metallographic examination observation surface;

6) judging whether the metallographic examination observation surface passes through the central axis of the 3 small holes or not according to the intersection point position in the step 5);

7) and (3) selecting a trapezoidal method or a triangular method according to whether the metallographic examination observation surface in the step 6) passes through the central axis of the small hole, and obtaining a reduction result of the hole wall profile characteristics of the 3 small holes.

2. The method for reducing the small hole profile characteristics for eliminating the tilting error of the metallographic examination observation surface according to claim 1, wherein the method for calculating the distance between the circle centers of the inlet and outlet sides of each hole and the metallographic examination observation surface in the step 4) comprises the following steps:

corresponding to 3 small hole inlet sides, P_n＝(E₀ ²-E_n ²)^1/2；(1)

Corresponding to 3 small hole outlet sides, Q_n＝(F₀ ²-F_n ²)^1/2；(2)

Wherein E is_nIs the width of the profile on the inlet side of the aperture, F_nIs the width of the profile at the exit side of the aperture, E₀Is the average value of the inlet pore diameter obtained in the step 2), F₀Is the average value of the outlet aperture, P, obtained in the step 2)_nThe distance Q between the center of the circle at the inlet side of each hole and the metallographic examination observation surface_nAnd n is equal to 1, 2 and 3, and is the distance between the center of the outlet side of each hole and the metallographic examination observation surface.

3. The method for reducing the small-hole profile characteristics for eliminating the tilting error of the metallographic observation surface according to the claims 1 and 2, wherein the method for determining the intersection point position of the metallographic observation surface and the reference surface on the inlet side in the step 5) comprises the following steps: according to the similar triangle relationship, the method is divided into four cases: (1) p₃＝max{P₁,P₂,P₃And P₁+2*P₂＝P₃The intersection point of the inlet sides is located between the holes 1 and 2; (2) p₁＝max{P₁,P₂,P₃And P₃+2*P₂＝P₁The intersection point of the inlet sides is located between the holes 2 and 3; (3) p₃＝max{P₁,P₂,P₃And P₁+P₃＝2*P₂The intersection point of the inlet sides is located on the left side of the hole 1; (4) p₁＝max{P₁,P₂,P₃And P₁+P₃＝2*P₂The entrance-side intersection is located on the right side of the hole 3.

4. The method for reducing the profile characteristics of the small hole for eliminating the tilting error of the metallographic observation surface according to the claims 1 and 2, wherein the method for determining the intersection point position of the metallographic observation surface and the reference surface at the outlet side in the step 5) comprises the following steps: according to the similar triangle relationship, the method is divided into four cases: (1) q₃＝max{Q₁,Q₂,Q₃And Q₁+2*Q₂＝Q₃The intersection point of the outlet sides is positioned between the hole 1 and the hole 2; (2) q₁＝max{Q₁,Q₂,Q₃And Q₃+2*Q₂＝Q₁The exit side intersection point is located between the holes 2 and 3; (3) q₃＝max{Q₁,Q₂,Q₃And Q₁+Q₃＝2*Q₂The intersection point of the outlet sides is positioned on the left side of the hole 1; (4) q₁＝max{Q₁,Q₂,Q₃And Q₁+Q₃＝2*Q₂The exit side intersection is located on the right side of the hole 3.

5. The method for reducing the profile characteristics of the small hole for eliminating the tilting error of the metallographic observation surface according to claim 1, wherein in the step 6) and the step 7), the method for judging whether the metallographic observation surface passes through the central axis of the 3 small holes comprises the following steps: if the intersection point of the inlet and the outlet of a certain hole is on the same side, the metallographic examination observation surface does not pass through the central axis of the hole, and the trapezoidal method is selected to reduce the outline of the hole wall; if the intersection point of the inlet and the outlet of a certain hole is on the opposite side, the metallographic examination observation surface passes through the central axis of the hole, and a triangular method is selected to reduce the outline of the hole wall.

6. The method for reducing the small-hole profile characteristics for eliminating the tilting error of a metallographic inspection observation surface according to claims 1 and 2, wherein the trapezoidal method in the step 7) is as follows:

the radius of the hole at different cross-sectional heights is

R_n(x)＝(4*((H_n-h_n)/H_n*Q_n+h_n/H_n*P_n)²+w_n(h)²)^1/2；(3)

Wherein h is_n＝x*H_nD, D is the thickness of the test panel, H_nFor symmetrical axial length, w, of the holes in the viewing surface_n(h) Is the width of the hole in the cross-section, h_nX varies from 0 to D for a certain cross-sectional height with respect to the exit side plane, and n is 1, 2, 3.

7. The method for reducing the small-hole profile characteristics for eliminating the tilting error of the metallographic inspection observation surface according to the claims 1 and 2, wherein the triangle method in the step 7) is as follows:

the radius of the hole at different cross-sectional heights is

R_n(x)＝(4*((H_n-h_n)/H_n*Q_n-h_n/H_n*P_n)²+w_n(h)²)^1/2；(4)

Wherein h is_n＝x*H_nD, D is the thickness of the test panel, H_nFor symmetrical axial length, w, of the holes in the viewing surface_n(h) Is the width of the hole in the cross-section, h_nX varies from 0 to D for a certain cross-sectional height with respect to the exit side plane, and n is 1, 2, 3.

8. The method for reducing the pore profile characteristics of the small pores for eliminating the tilting errors of the metallographic examination observation surface according to claim 1, wherein the step 7) is as follows: establishing a reduction coordinate system of the 3 small holes, wherein the Z-axis direction of the coordinate system is coincident with the central axis direction of the small holes, the Z-axis zero plane is positioned on the outlet plane of the test plate, and the radius R is measured_n(x) And drawing the function relation along with x in the reduction coordinate system to obtain the change relation of the hole wall profile characteristic along with the hole depth.

Background

The method is characterized in that small holes such as a gas film hole and an oil injection hole exist in an aviation and aerospace hot end part, the detection of the aperture of the small hole at present mainly depends on plug gauges with different diameters, but the method can only reflect the minimum sectional area of the small hole, and the change rule of the hole wall profile along with the depth cannot be obtained; the optical scanning can obtain the contour and the roughness of the hole wall in a certain range close to the hole opening, but the number of detectable points is sharply reduced along with the increase of the hole depth, and the number of noise points is obviously increased; the inspection precision of the industrial CT is affected by the intensity of the radiation source, the image resolution of the layered scanning is low, and the distribution state of the thermally induced defects such as the hole wall re-melting layer cannot be provided. The metallographic examination is a common examination method capable of simultaneously presenting the geometric characteristics of the small hole and the metallurgical quality, and particularly when the small hole is manufactured by adopting special processing methods such as electric spark, electrochemistry, laser and the like, the small hole is subjected to sectioning metallographic examination according to the process confirmation requirement and the quality acceptance standard, and examination data containing the contents such as hole wall roughness, a remelted layer/heat affected zone/electrochemical corrosion layer thickness and the like can be obtained. The measured value is used as a judgment basis for judging whether the processing state of the small hole meets the service working condition or not on one hand, and provides basic data for selecting a small hole post-processing process, such as abrasive flow/magnetic grinding and the like on the other hand.

However, the existing standards and specifications for the metallographic examination of the small holes do not provide the requirements on the position relationship between the metallographic examination observation surface and the small holes of the sample. In fact, if the metallographic examination observation surface deviates from the central axis of the hole, the deviation of the characteristic dimension of the small hole and the metallurgical defect examination result can be caused, and further, part of part gas film holes are scrapped due to the fact that the thickness of the remelted layer of the metallographic examination exceeds the standard. And because the aperture size of the small hole is generally below 0.5mm, the grinding depth is difficult to be effectively controlled under the condition of manual polishing, and the relative position relationship between a metallographic examination observation surface and the hole cannot be ensured. The development of a reduction method capable of correcting the deviation of a measured value caused by tilting of a metallographic examination observation surface is urgently needed, and the authenticity of small-hole metallographic examination data is improved.

Disclosure of Invention

The invention provides a method for reducing the outline characteristics of a small hole for eliminating the tilting error of a metallographic examination observation surface, which aims to solve the problems.

The invention realizes the purpose through the following technical scheme, which comprises the following steps:

1) selecting a test board with parallel upper and lower surfaces, and preparing 3 collinear equidistant small holes on the test board by adopting the same processing technology;

2) appointing any side of the test board to be tested as a small hole inlet side and the other side as an outlet side, enabling a metallographic examination observation surface to pass through the 3 small holes, measuring the aperture of the inlet and the outlet of the small hole, and respectively calculating an average value;

3) cutting along the edge at one side of the 3 small holes, and inlaying and grinding according to a standard metallographic sample preparation process to enable the 3 small holes to be completely presented from the inlet to the outlet side of the whole side wall profile under metallographic examination;

4) measuring the contour widths of the inlet and outlet sides of the 3 small holes, and calculating the distance between the circle center of the inlet and outlet sides of each hole and the metallographic examination observation surface according to the average value in the step 2);

5) determining a reference plane formed by the metallographic examination observation surface and the central axis of the 3 small holes at the intersection point of the inlet and the outlet side according to the distance between the circle centers of the inlet and the outlet side in the step 4) and the metallographic examination observation surface;

6) judging whether the metallographic examination observation surface passes through the central axis of the 3 small holes or not according to the intersection point position in the step 5);

7) and (3) selecting a trapezoidal method or a triangular method according to whether the metallographic examination observation surface in the step 6) passes through the central axis of the small hole, and obtaining a reduction result of the hole wall profile characteristics of the 3 small holes.

Preferably, the method for calculating the distance between the circle centers of the inlet and the outlet of each hole and the metallographic examination observation surface in the step 4) comprises the following steps:

corresponding to 3 small hole inlet sides, P_n＝(E₀ ²-E_n ²)^1/2； (1)

Corresponding to 3 small hole outlet sides, Q_n＝(F₀ ²-F_n ²)^1/2； (2)

E_nIs the width of the profile on the inlet side of the aperture, F_nWidth of contour at exit side of small hole, E₀Is the average value of the inlet pore diameter obtained in the step 2), F₀Is the average value of the outlet aperture, P, obtained in the step 2)_nThe distance Q between the center of the circle at the inlet side of each hole and the metallographic examination observation surface_nAnd n is equal to 1, 2 and 3, and is the distance between the center of the outlet side of each hole and the metallographic examination observation surface.

Preferably, the method for determining the intersection point position of the metallographic examination observation surface and the reference surface on the inlet side in the step 5) comprises the following steps: according to the similar triangle relationship, the method is divided into four cases: (1) p₃＝max{P₁,P₂,P₃And P₁+2*P₂＝P₃The intersection point of the inlet sides is located between the holes 1 and 2; (2) p₁＝max{P₁,P₂,P₃And P₃+2*P₂＝P₁The intersection point of the inlet sides is located between the holes 2 and 3; (3) p₃＝max{P₁,P₂,P₃And P₁+P₃＝2*P₂Then, thenThe intersection point of the inlet sides is positioned at the left side of the hole 1; (4) p₁＝max{P₁,P₂,P₃And P₁+P₃＝2*P₂The entrance-side intersection is located on the right side of the hole 3.

Preferably, the method for determining the intersection point position of the metallographic examination observation surface and the reference surface on the outlet side in the step 5) comprises the following steps: according to the similar triangle relationship, the method is divided into four cases: (1) q₃＝max{Q₁,Q₂,Q₃And Q₁+2*Q₂＝Q₃The intersection point of the outlet sides is positioned between the hole 1 and the hole 2; (2) q₁＝max{Q₁,Q₂,Q₃And Q₃+2*Q₂＝Q₁The exit side intersection point is located between the holes 2 and 3; (3) q₃＝max{Q₁,Q₂,Q₃And Q₁+Q₃＝2*Q₂The intersection point of the outlet sides is positioned on the left side of the hole 1; (4) q₁＝max{Q₁,Q₂,Q₃And Q₁+Q₃＝2*Q₂The exit side intersection is located on the right side of the hole 3.

Preferably, in the step 6) and the step 7), the method for judging whether the metallographic observation surface passes through the central axis of the 3 small holes comprises the following steps: if the intersection point of the inlet and the outlet of a certain hole is on the same side, the metallographic examination observation surface does not pass through the central axis of the hole, and a trapezoidal method is selected to reduce the outline of the hole wall; if the intersection point of the inlet and the outlet of a certain hole is positioned on the opposite side, the metallographic examination observation surface passes through the central axis of the hole, and a triangular method is selected to reduce the outline of the hole wall.

Preferably, the trapezoidal method in step 7) is:

the radius of the hole at different cross-sectional heights is

R_n(x)＝(4*((H_n-h_n)/H_n*Q_n+h_n/H_n*P_n)²+w_n(h)²)^1/2； (3)

Wherein h is_n＝x*H_nD, D is the thickness of the test panel, H_nFor symmetrical axial length, w, of the holes in the viewing surface_n(h) Is on the cross sectionWidth of the hole, h_nX varies from 0 to D for a certain cross-sectional height with respect to the exit side plane, and n is 1, 2, 3.

Preferably, the triangle method in step 7) is:

the radius of the hole at different cross-sectional heights is

R_n(x)＝(4*((H_n-h_n)/H_n*Q_n-h_n/H_n*P_n)²+w_n(h)²)^1/2； (4)

Wherein h is_n＝x*H_nD, D is the thickness of the test panel, H_nFor symmetrical axial length, w, of the holes in the viewing surface_n(h) Is the width of the hole in the cross-section, h_nX varies from 0 to D for a certain cross-sectional height with respect to the exit side plane, and n is 1, 2, 3.

Preferably, the step 7) of reducing the hole wall profile features comprises the following steps: establishing a reduction coordinate system of the 3 small holes, wherein the Z-axis direction of the coordinate system is coincident with the central axis direction of the small holes, the Z-axis zero plane is positioned on the outlet plane of the test plate, and the radius R is measured_n(x) And drawing the function relation along with x in the reduction coordinate system to obtain the change relation of the hole wall profile characteristic along with the hole depth.

The invention has the beneficial effects that:

according to the method, the mutual position relation between the central axis of the 3 small holes and the metallographic examination observation surface is measured, on the basis, the hole wall profile characteristics are reduced based on a trapezoidal method and a triangular method respectively, the change relation of the hole wall profile and the roughness along with the hole depth is formed, the correction of the deviation of the measured value of the hole wall profile caused by the tilting of the metallographic examination observation surface can be realized, the accuracy of the metallographic examination data of the small holes is improved, and the rejection of the small holes such as aviation blade part air film holes and the like due to the inaccuracy of the metallographic examination data can be avoided.

Drawings

FIG. 1 is a plan view of the arrangement of small holes on a test plate.

FIG. 2 is a cross-sectional view of the inlet and outlet of a planar aperture to be measured.

FIG. 3 shows that the intersection point of the metallographic observation surface and the reference plane of the line connecting the hole centers is located between the hole 1 and the hole 2.

FIG. 4 shows the intersection point of the metallographic observation surface and the reference plane of the line connecting the hole centers is located between the hole 2 and the hole 3.

FIG. 5 shows that the intersection point of the metallographic examination observation surface and the reference plane of the line connecting the hole centers is located on the left side of the hole 1.

FIG. 6 shows that the intersection point of the metallographic examination observation surface and the reference plane of the line connecting the hole centers is located on the right side of the hole 3.

FIG. 7 is a schematic view of a metallographic examination observation surface not passing through the central axis of the hole.

FIG. 8 is a schematic view of a metallographic observation surface passing through a hole central axis.

FIG. 9 is a schematic diagram of a trapezoidal reduction process.

FIG. 10 is a schematic diagram of a triangular reduction process.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and specific examples 1 and 2, which are illustrative, but not limiting, of the present invention, and any obvious modifications, substitutions or alterations made by those skilled in the art without inventive faculty are within the scope of the present invention.

Specific example 1:

referring to fig. 1 and 2, three collinear equidistant small holes are machined on a test plate with two polished surfaces by an ultrafast laser spiral rotary cutting process, the thickness of the test plate is 2.00mm, the diameters of the inlet and outlet of 3 holes are measured by metallographic examination, and the average value is calculated and recorded as E₀0.630mm and F₀0.582mm, as shown in fig. 1. The method is characterized in that electric spark slow-moving wire cutting is adopted, cutting is completed at a position about 1mm away from the edge of a side hole of a small hole of 3 small holes, sample inlaying and grinding and polishing operations of a sample with the small hole are completed according to a standard metallographic sample preparation process, flat grinding is guaranteed to the greatest extent in the sample grinding process, the 6 side wall profiles of the small holes from an inlet to an outlet are completely shown after grinding and in-place polishing, blind holes and crossed holes do not exist, and accuracy of follow-up metallographic examination is guaranteed.

See fig. 2, under metallographic examination, the sample was rotated so that the inlet side of 3 wells was above the field of view and the outlet side was below, and from left to right, they were labeled as well 1, well 2, well 3. Adjusting the magnification and observation field area of the metallographic microscope, measuring the width of an inlet and an outlet of each hole respectively, and recording the width of the inlet as E₁＝0.603mm、E₂＝0.627mm、E₃0.548mm, the outlet width is denoted F₁＝0.413mm、F₂＝0.557mm、F₃0.574 mm. According to the Pythagorean theorem, calculating the distance from the central axis of each hole to the inlet and outlet of the observation surface of each hole to obtain the distance P corresponding to the inlet side of 3 holes₁＝(E₀ ²-E₁ ²)^1/2＝0.182mm，P₂＝(E₀ ²-E₂ ²)^1/2＝0.064mm，P₃＝(E₀ ²-E₃ ²)^1/20.310mm, corresponding to 3 holes with a distance Q from the outlet side₁＝(F₀ ²-F₁ ²)^1/2＝0.407mm，Q₂＝(F₀ ²-F₂ ²)^1/2＝0.161mm，Q₃＝(F₀ ²-F₃ ²)^1/2＝0.085mm。

Calculated that the inlet side distance satisfies P₃＝max{P₁,P₂,P₃And P₁+2*P₂＝P₃On the surface of the sample at one side of the inlet, the intersection point of the metallographic examination observation surface and the reference surface where the central axis is located between the hole 1 and the hole 2, as shown in fig. 3; the distance of the outlet side satisfies Q₁＝max{Q₁,Q₂,Q₃And Q₃+2*Q₂＝Q₁Then, on the surface of the sample on the outlet side, the intersection of the metallographic examination observation plane and the reference plane on which the central axis is located between the hole 2 and the hole 3, as shown in fig. 4. Thus, the position relation between the metallographic observation surface and the reference surface is judged, and for the hole 1 and the hole 3, the metallographic observation surface is arranged on one side of the reference surface, namely the metallographic observation surface does not pass through the central axis of the hole, as shown in fig. 7; for the hole 2, the metallographic observation surface and the reference surface are arranged in the holeThe portions intersect so that the viewing surface passes through the central axis of the bore, as shown in figure 8.

For the case shown in fig. 7, the trapezoidal method is used to reduce the hole wall profile, specifically as shown in fig. 9, taking the reduction process of the hole 1 as an example: measuring the distance H from the inlet midpoint to the outlet midpoint of the hole 1 under metallographic examination₁2.013mm, keeping the field of view constant, taking any sectional line parallel to the inlet and outlet planes, the distance h from the middle point of the sectional line to the middle point of the outlet being 1.562mm, the distance w between the intersection points of the sectional line and the two side walls of the hole 1₁(h) 0.564 mm. The plane of the same height as the sectional line intersects the central axis of the hole, and the height x is H D/H₁1.562 x 2/2.013 x 1.552mm, corresponding to R₁(x)＝(((H₁-h)/H₁*Q₁+h/H₁*P₁)²+w₁(h)²)^1/2And/2 is 0.305 mm. Adjusting the height and spacing of the sectional lines to obtain R₁(x) As a function of x.

For the case shown in fig. 8, the hole wall profile is restored by a triangular method, specifically as shown in fig. 10, taking the restoration process of the hole 2 as an example: measuring the distance H from the inlet midpoint to the outlet midpoint of the hole 2 under metallographic examination₂2.013mm, keeping the field constant, taking any sectional line parallel to the inlet and outlet planes, the distance h between the middle point of the sectional line and the middle point of the outlet being 1.008mm, and the distance w between the intersection points of the sectional line and the two side walls of the hole 2₂(h) 0.615 mm. The plane of the same height as the sectional line intersects the central axis of the hole, and the height x is H D/H₂1.008 x 2/2.013 x 1.001mm, corresponding to R₂(x)＝(((H₂-h)/H₂*Q₂-h/H₂*P₂)²+w₂(h)²)^1/2And/2 is 0.308 mm. Adjusting the height and spacing of the sectional lines to obtain R₂(x) As a function of x.

The reduction method of well 3 is the same as that of well 1.

Establishing a reduction coordinate system of 3 holes, wherein the Z-axis direction of the coordinate system is coincident with the central axis direction of the holes, the zero plane of the Z direction is positioned on the outlet plane of the test plate, and the radius R is respectively measured₁(x)、R₂(x)、R₃(x) As a function of x or of a particular section heightAnd drawing the position of the side wall in a reduction coordinate system to obtain the change relation of the hole wall profile and the roughness along with the hole depth.

Specific example 2:

referring to fig. 1 and 2, three collinear and equidistant holes were machined in a double-polished test plate with an electric spark machine, the thickness of the test plate was 3.00mm, metallographic examination was performed, and the diameters of the entrance and exit holes of 3 holes were measured and the average value was calculated and recorded as E₀0.857mm and F₀0.732mm as shown in fig. 1. The method is characterized in that electric spark slow-moving wire cutting is adopted, cutting is completed at a position about 1mm away from the edge of a side hole of a small hole of 3 small holes, sample inlaying and grinding and polishing operations of a sample with the small hole are completed according to a standard metallographic sample preparation process, flat grinding is guaranteed to the greatest extent in the sample grinding process, the 6 side wall profiles of the small holes from an inlet to an outlet are completely shown after grinding and in-place polishing, blind holes and crossed holes do not exist, and accuracy of follow-up metallographic examination is guaranteed.

Under metallographic examination, the specimen was rotated so that the inlet side of 3 wells was above the field of view and the outlet side was below, labeled well 1, well 2, well 3 in order from left to right. Adjusting the magnification and observation field area of the metallographic microscope, measuring the width of an inlet and an outlet of each hole respectively, and recording the width of the inlet as E₁＝0.844mm、E₂＝0.769mm、E₃0.602mm, the outlet width is respectively marked as F₁＝0.299mm、F₂＝0.588mm、F₃0.703mm, see fig. 2. According to the Pythagorean theorem, calculating the distance from the central axis of each hole to the inlet and outlet of the observation surface of each hole to obtain the distance P corresponding to the inlet side of 3 holes₁＝(E₀ ²-E₁ ²)^1/2＝0.146mm，P₂＝(E₀ ²-E₂ ²)^1/2＝0.378mm，P₃＝(E₀ ²-E₃ ²)^1/20.610mm, corresponding to 3 holes with a distance Q from the outlet side₁＝(F₀ ²-F₁ ²)^1/2＝0.668mm，Q₂＝(F₀ ²-F₂ ²)^1/2＝0.436mm，Q₃＝(F₀ ²-F₃ ²)^1/2＝0.204mm。

Calculated that the inlet side distance satisfies P₃＝max{P₁,P₂,P₃And P₁+P₃＝2*P₂Then, on the surface of the sample at the inlet side, the intersection point of the observation plane and the reference plane where the central axis is located at the left side of the hole 1, as shown in fig. 5; the distance of the outlet side satisfies Q₁＝max{Q₁,Q₂,Q₃And Q₁+Q₃＝2*Q₂Then, on the outlet side sample surface, the intersection of the observation plane and the reference plane on which the center axis is located on the right side of the hole 3, as shown in fig. 6. The positional relationship between the observation plane and the reference plane is thus determined, and the observation plane and the reference plane intersect each other in the hole 1, the hole 2, and the hole 3, and therefore the observation plane passes through the central axis of the 3 small holes, as shown in fig. 8.

The hole wall profile and the remelted layer need to be reduced by a triangular method, as shown in fig. 10, taking a hole 1 as an example: the distance H from the inlet midpoint to the outlet midpoint of the hole 1 is measured under the metallographic phase₁3.108mm, keeping the field of view constant, taking any sectional line parallel to the plane of the inlet and outlet, the distance h between the middle point of the sectional line and the middle point of the outlet being 2.325mm, and the distance w between the intersection points of the sectional line and the two side walls of the hole 1₁(h) 0.798mm, the distance between the intersection points of the line and the remelted layer/substrate interface on both sides of the hole 1 is w₁' (h) ═ 0.825 mm. The plane of the same height as the sectional line intersects the central axis of the hole, and the height x is H D/H₁2.325 h 3/3.108 h 2.244mm, corresponding to the hole wall contour radius R₁(x)＝(((H₁-h)/H₁*Q₁-h/H₁*P₁)²+w₁(h)²)^1/20.400 mm/2, and remelted layer/substrate interface radius R₁’(x)＝(((H₁-h)/H₁*Q₁-h/H₁*P₁)²+w₁’(h)²)^1/2And/2 is 0.414mm, the thickness of the remelting layer at the position is 0.014 mm. According to the measurement precision requirement, the height and the spacing of the transversal lines can be adjusted to obtain R₁(x) And R₁' (x) as a function of x.

The reduction method of the wells 2 and 3 is the same as that of the well 1.

Establishing a reduction coordinate system of 3 holes, wherein the Z-axis direction of the coordinate system is coincident with the central axis direction of the holes, the zero plane of the Z direction is positioned on the outlet plane of the test plate, and the radius R is respectively measured₁(x)、R₂(x)、R₃(x) And a remelted layer/substrate interface radius R₁’(x)、R₂’(x)、R₃'x' is plotted in a reduction coordinate system along with the function relation of x or the position of the side wall with a certain specific section height, and the change relation of the hole wall profile and the remelted layer thickness along with the hole depth is obtained.