Quantitative evaluation method for microscopic defect size of metal material
By determining the stress state and maximum main stress plane of the parts, the smooth curve transition calculation of microscopic defects in metal materials is solved, which is difficult to conduct quantitative evaluation in the prior art, and the irregular shape defects and differences are achieved Dimension measurement and comparison of type defects improves the accuracy of evaluation of material properties and potential failure points.
Patent Information
- Application Number
- CN202411192585.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-28
- Publication Date
- 2024-12-10
AI Technical Summary
The prior art is difficult to quantitatively evaluate microscopic defects in metal materials, especially dimensional measurement and comparison of irregular shape defects and different types of defects, making it difficult to evaluate their impact on material failure.
By determining the actual stress state and maximum principal stress plane of the component, the dimension range of the microscopic defect is defined as ≤1mm, the linear dimensions of the defect are calculated using the smooth curve transition and the outer boundary of the envelope defect, including the irregular defects, Specific calculation methods for cracks, inclusions, pores, etc. to achieve quantitative evaluation of defects.
Quantitative measurement and comparison of different defects in metal materials is achieved, allowing its impact on the material to be evaluated, thereby more accurately understanding the properties and potential failure points of the material.
Smart Images
Figure CN119104009A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of microscopic defect evaluation, and in particular to a method for quantitatively evaluating the size of microscopic defects of metal materials. Background Art
[0002] Microscopic defects of metal materials include oxidation, decarburization, segregation, pores, shrinkage and porosity, inclusions, cracks, machining marks, scratches, etc. The formation of these defects is related to the smelting, processing and use environment of metal materials. Typical microscopic defects usually occur in different processing flows, which are difficult to avoid completely. Shrinkage, porosity, pores, segregation, etc. usually appear in the casting process; white spots, oxidation, decarburization, etc. usually appear in the forging process; cracks, oxidation, decarburization, etc. usually appear in the heat treatment process.
[0003] There are different evaluation standards and methods for different defects. For example, non-metallic inclusions in steel are usually evaluated using GB / T10561; decarburization is usually evaluated using GB / T224; segregation / shrinkage / shrinkage defects in aluminum are usually evaluated using GB / T26492. These standards are basically qualitative evaluation methods, and it is difficult to make a quantitative evaluation of defects. Usually, defects of different types and sizes exist in the material at the same time. For example, non-metallic inclusions are a non-metallic compound that is produced during the deoxidation process and solidification of molten steel. Shrinkage refers to the macroscopic void defects caused by shrinkage when the ingot is poured and other castings are solidified at the top of the casting. If the shrinkage is not removed completely, wrinkles or holes will be formed in the center of the cross section after the ingot is rolled into a profile, and severe porosity, segregation and accumulation of oxygen products often occur nearby. Pores, also known as air holes, are one of the most common defects in casting production. They are produced inside, on the surface or near the surface of castings. They are round, long and irregular in size. They are either single or aggregated. The pore walls are smooth and white in color, sometimes covered with a layer of oxide scale. Cracks refer to small cracks in materials caused by stress or environmental factors. These cracks can be tiny cracks inside the material or cracks on the surface. The formation of cracks may be caused by a variety of factors, including stress inside the material, external loads, temperature changes, etc. Irregular non-metallic inclusions and cracks exist in steel at the same time. It will be very difficult to measure and evaluate the quantitative size of these two defects and which one will be the key defect causing material failure. Defects observed on the failed fracture of parts (for example, non-metallic inclusions), but the fracture is not a regular plane, making the defect size on the fracture more difficult to evaluate.
[0004] There are various microscopic defects in metal materials. There are different categories, including inclusions / cracks / notches / deflections / pores / shrinkage cavities, etc.; different shapes, (continuous / intermittent) long strips / spherical / worm-like / flocculated / pointed and other irregular shapes; at the same time, these defects are located in different positions in the parts, some are in the core of the parts, some are on the surface of the parts, some are tangent to the surface of the parts, and some are at a certain distance from the surface of the parts. All these factors make it very difficult to quantitatively measure and evaluate these defects. Example 1, a curved crack and an irregular inclusion, how to measure the quantitative size and how to compare. Example 2, an irregular inclusion on the fracture, due to the unevenness of the fracture surface, considering the irregular shape of the inclusion, how to measure the size of the inclusion, it will be difficult to evaluate. Cut and sample according to the specified requirements → grind → polish → observe and rate under a metallographic microscope. The existing technology can only perform qualitative evaluation and comparison, but cannot quantitatively measure the defect size, and it is even more impossible to measure and evaluate irregular-shaped defects. Generally speaking, actual defects are all irregular in shape, and the current standards have been approximated to spherical / linear / strip-shaped, etc. It is also impossible to measure and compare the sizes of different types of defects, such as long cracks and inclusions of similar size. There is no unified method for measuring and comparing the load direction perpendicular to the paper surface, and whether the reduction effects of these two defects under external loads are different, resulting in matrix discontinuity. Therefore, it is very important to solve this problem. Summary of the invention
[0005] In view of this, the purpose of the present invention is to provide a method for quantitatively evaluating the size of microscopic defects in metal materials to solve the problems raised in the above background technology.
[0006] Based on the above purpose, the present invention provides a method for quantitatively evaluating the size of microscopic defects in metal materials, comprising the following steps: Step 1: determine the actual stress state of the component, determine the maximum principal stress plane, and determine that the observation plane of the defect is the vertical plane of the maximum principal stress; Step 2: The size range of microscopic defects is defined as ≤1 mm; Step three, make the defects of concern visible; Step 4: Evaluate the defect size: smooth the curve transition, envelop the outer boundary of the defect, calculate the outer boundary area A of the curve envelope, and then take the square root of A to obtain the defect linear size √A; First, for a single internal irregular defect, the area A is calculated directly according to the outer envelope, and then the square root √A is taken; Second, if there are two internal defects and the gap between the defects is not large enough to accommodate a relatively small defect, it is necessary to smoothly envelope the outer boundaries of the two defects and then calculate √A; Third, if the defect is adjacent to the workpiece surface, it is necessary to smoothly envelope the defect and connect it to the surface before calculating √A; Fourth, for a single curved crack with a certain opening or with bifurcation / secondary cracks, directly calculate the square root of the area contained in the outer envelope of the crack, √A; Fifth, if there are secondary small cracks or microscopic openings on both sides or one side of the inclusions or pores / shrinkage holes that are approximately circular defects, the outer envelope needs to include the inclusions such as pores / shrinkage holes and microscopic openings, and √A is calculated; Sixth, for a single curved strip inclusion, directly calculate the square root of the area contained by the outer envelope of the inclusion √A; Seventh, the outer surface processing marks or scratches are measured by measuring the length of the outer surface defect l 1 and width c 1 , and l 1 >10c 1 , using the formula √A=c 1 *√10; Eighth, welding pores / pinholes / deep cracks / other defects that penetrate the surface, by measuring the depth of the pinhole l 2 and width c 2 , and l 2 >5c 2 , using the formula √A=c 2 *√10; Ninth, for irregular defects on the fracture, the effective projection area of the defect on the vertical plane of the maximum principal stress, and then calculate √A.
[0007] Preferably, between step 2 and step 3, there is also the step of merging adjacent defects.
[0008] Preferably, merging adjacent defects includes two situations: First, adjacent internal defects. If the gap between two adjacent defects is large enough to insert a smaller defect, the two defects will be evaluated separately, and there will be no merging effect between the two defects. If the gap between two adjacent defects is so small that a smaller defect cannot be inserted, the two defects need to be combined for evaluation, and the two defects need to be merged into one large defect. Second, the internal defect is adjacent to the workpiece surface. If the ratio of the approximate radius a of the defect to the distance h from the defect center to the surface is a / h ≥ 0.8, then the internal defect and the workpiece surface interact and need to be evaluated together.
[0009] Preferably, in the third step of step three, in addition to removing the defect adjacent to the workpiece surface, a / h≥0.8 is also required, so the defect needs to be smoothly enveloped and connected to the surface, and then √A is calculated.
[0010] Preferably, the irregular defect can be outlined by smooth transition, approximately in the shape of a circle; wherein a / h=1 means that the defect is just tangent to the surface, and a / h>1 means that the defect is exposed on the outer surface of the workpiece.
[0011] Preferably, the smooth curve transition in step 4 should not have obvious depressions.
[0012] Preferably, in step 1, the external load direction / principal stress direction of the defect in the maximum principal stress plane is determined to be perpendicular to the paper surface.
[0013] Preferably, the size of the microscopic defect to be quantitatively evaluated is the maximum linear length of the outer contour of the defect.
[0014] Beneficial effects of the present invention: The present invention first determines the stress state, determines the maximum principal stress plane, and then determines the size range of microscopic defects ≤1mm, then merges adjacent defects, and then displays the defects, and finally evaluates them according to the defect type. The evaluation is finally displayed in the form of data, so that measurement and evaluation can be carried out, and comparison can be made, so as to realize quantitative evaluation and comparison of different defects in the material. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0016] Figure 1 It is a flow chart of a specific implementation method of the present invention.
[0017] Figure 2 This is a schematic diagram of step S2 of a specific embodiment of the present invention. Figure 1 .
[0018] Figure 3 This is a schematic diagram of step S2 of a specific embodiment of the present invention. Figure 2 .
[0019] Figure 4 This is a schematic diagram of step S2 of a specific embodiment of the present invention. Figure 3 .
[0020] Figure 5 This is a schematic diagram of step S2 of a specific embodiment of the present invention. Figure 4 .
[0021] Figure 6 It is a schematic diagram of step S31 of a specific implementation mode of the present invention.
[0022] Figure 7It is a schematic diagram of step S32 of a specific implementation manner of the present invention.
[0023] Figure 8 It is a schematic diagram of step S51 of a specific implementation mode of the present invention.
[0024] Fig. 9 It is a schematic diagram of step S52 of a specific implementation mode of the present invention.
[0025] Fig.10 It is a schematic diagram of step S53 of a specific implementation mode of the present invention.
[0026] Fig.11 It is a schematic diagram of step S54 of a specific implementation mode of the present invention.
[0027] Fig.12 It is a schematic diagram of step S55 of a specific implementation mode of the present invention.
[0028] Fig.13 It is a schematic diagram of step S56 of a specific implementation mode of the present invention.
[0029] Fig.14 It is a schematic diagram of step S57 of a specific implementation mode of the present invention.
[0030] Fig.15 It is a schematic diagram of step S58 of a specific implementation mode of the present invention.
[0031] Fig.16 It is a schematic diagram of step S59 of a specific implementation mode of the present invention. DETAILED DESCRIPTION
[0032] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.
[0033] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0034] like Figure 1 As shown, this embodiment provides a method for quantitatively evaluating the size of microscopic defects in metal materials, comprising the following steps: S1, determine the actual stress state of the component, determine the maximum principal stress plane, and determine that the observation plane of the defect is the maximum principal stress vertical plane. The external load direction / principal stress direction of the defect in the maximum principal stress plane is perpendicular to the paper surface; S2, the size range of microscopic defects is defined as ≤1 mm, and the size of microscopic defects is the maximum linear length of the outer contour of the defect, such as Figure 2 Shown is the projected length of the bending crack, Figure 3 The diameter of the circle is shown as Figure 4 The length or approximate diameter of an irregular shape is shown, e.g. Figure 5 The projection length is shown as a long strip; S3, merges adjacent defects, and includes two cases: S31, such as Figure 6 As shown in the figure, for adjacent internal defects, if the gap between two adjacent defects can be used to insert a smaller defect, the two defects are evaluated separately, and there is no merging effect between the two defects; if the gap between two adjacent defects is so small that a smaller defect cannot be inserted, the two defects need to be combined for evaluation, and the two defects need to be merged into one large defect; S32, internal defects are adjacent to the workpiece surface. If the ratio of the approximate radius a of the defect to the distance h from the defect center to the surface is a / h ≥ 0.8, the internal defect and the workpiece surface interact and need to be evaluated together; Figure 7 As shown in the figure, the irregular defect can be outlined by smooth transition, which is approximately a circle; where a / h=1 means that the defect is just tangent to the surface, and a / h>1 means that the defect is exposed on the outer surface of the workpiece; S4, making the defects of concern visible; S5, evaluate the defect size: smooth curve transition, the smooth curve transition should not have obvious depression, envelop the outer boundary of the defect, calculate the outer boundary area A of the curve envelope, and then square A to get the linear size of the defect √A; S51, such as Figure 8 As shown, for a single internal irregular defect, the area A is calculated directly according to the outer envelope, and then the square root √A is taken; S52, such as Fig. 9 As shown in the figure, there are two internal defects, and the gap between the defects is not large enough to accommodate relatively small defects. In this case, the outer boundaries of the two defects need to be smoothly enveloped before calculating √A. S53, such as Fig.10 As shown, if the defect is adjacent to the workpiece surface and a / h ≥ 0.8, it is necessary to smoothly envelope the defect and connect it to the surface, and then calculate √A; S54, such as Fig.11 As shown, for a single curved crack with a certain opening or with bifurcation / secondary cracks, the square root of the area contained in the outer envelope of the crack, √A, is directly calculated; S55, such as Fig.12 As shown, C is the crack generated, inclusions or pores / shrinkage holes and other approximately circular defects have secondary small cracks on both sides or one side, or microscopic openings, the outer envelope needs to include inclusions such as pores / shrinkage holes and microscopic openings, and √A is calculated; S56, such as Fig.13 As shown, for a single curved strip inclusion, the square root of the area contained in the outer envelope of the inclusion, √A, is directly calculated; S57, such as Fig.14 As shown in the figure, the outer surface processing marks or scratches are measured by measuring the length of the outer surface defect l 1 and width c 1 , and l 1 >10c 1 , using the formula √A=c 1 *√10; S58, such as Fig.15 As shown, welding pores / pinholes / deep cracks / other defects that penetrate the surface are measured by measuring the depth of the pinhole l 2 and width c 2 , and l 2 >5c 2 , using the formula √A=c 2 *√10; S59, such as Fig.16 As shown, the irregular defects on the fracture surface, the effective projected area of the defect on the vertical plane of the maximum principal stress, and then calculate √A.
[0035] Existing technologies can only perform qualitative evaluation and comparison, but cannot quantitatively measure defect sizes, and are even more unable to measure and evaluate irregularly shaped defects. Generally speaking, actual defects are all irregular in shape, and the current standards have all been approximated to be spherical / linear / strip-shaped, etc., and the sizes of different types of defects cannot be measured and compared. For example, long strip cracks and inclusions of similar sizes cannot be measured and compared. Whether the reduction effects of these two defects under external loads are different and cause matrix discontinuity; the evaluation of this embodiment is ultimately presented in the form of data, so that measurement, evaluation, and comparison can be performed, and quantitative evaluation and comparison of different defects in the material can be achieved.
[0036] It should be understood by those skilled in the art that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.
Claims
1. A method for quantitatively evaluating the size of microscopic defects in metal materials, characterized in that: The following steps are included: Step 1: determine the actual stress state of the component, determine the maximum principal stress plane, and determine that the observation plane of the defect is the vertical plane of the maximum principal stress; Step 2: The size range of microscopic defects is defined as ≤1 mm; Step three, make the defects of concern visible; Step 4: Evaluate the defect size: smooth the curve transition, envelop the outer boundary of the defect, calculate the outer boundary area A of the curve envelope, and then take the square root of A to obtain the linear size of the defect √A; First, for a single internal irregular defect, the area A is calculated directly according to the outer envelope, and then the square root √A is taken; Second, if there are two internal defects and the gap between the defects is not large enough to accommodate a relatively small defect, it is necessary to smoothly envelope the outer boundaries of the two defects and then calculate √A; Third, if the defect is adjacent to the workpiece surface, it is necessary to smoothly envelope the defect and connect it to the surface before calculating √A; Fourth, for a single curved crack with a certain opening or with bifurcation / secondary cracks, directly calculate the square root of the area contained in the outer envelope of the crack, √A; Fifth, if there are secondary small cracks or microscopic openings on both sides or one side of the inclusions or pores / shrinkage holes that are approximately circular defects, the outer envelope needs to include the inclusions such as pores / shrinkage holes and microscopic openings, and √A is calculated; Sixth, for a single curved strip inclusion, directly calculate the square root of the area contained by the outer envelope of the inclusion √A; Seventh, the outer surface machining marks or scratches are calculated by measuring the length l1 and width c1 of the outer surface defects, and l1>10c1, using the formula √A=c1*√10; Eighth, welding pores / pinholes / deep cracks / other defects that penetrate the surface are calculated by measuring the depth l2 and width c2 of the pinhole, and l2>5c2, using the formula √A=c2*√10; Ninth, for irregular defects on the fracture, the effective projection area of the defect on the vertical plane of the maximum principal stress, and then calculate √A.
2. The method for quantitatively evaluating the size of microscopic defects in metal materials according to claim 1, characterized in that: There is also a step between step 2 and step 3: merging adjacent defects.
3. The method for quantitatively evaluating the size of microscopic defects in metal materials according to claim 2, characterized in that: There are two situations for merging adjacent defects: First, adjacent internal defects. If the gap between two adjacent defects is large enough to insert a smaller defect, the two defects will be evaluated separately, and there will be no merging effect between the two defects. If the gap between two adjacent defects is so small that a smaller defect cannot be inserted, the two defects need to be combined for evaluation, and the two defects need to be merged into one large defect. Second, the internal defect is adjacent to the workpiece surface. If the ratio of the approximate radius a of the defect to the distance h from the defect center to the surface is a / h ≥ 0.8, then the internal defect and the workpiece surface interact and need to be evaluated together.
4. The method for quantitatively evaluating the size of microscopic defects in metal materials according to claim 3, characterized in that: In the third step of step three, in addition to removing the defect adjacent to the workpiece surface, a / h ≥ 0.8 is also required, so the defect needs to be smoothly enveloped and connected to the surface, and then √A is calculated.
5. The method for quantitatively evaluating the size of microscopic defects in metal materials according to claim 3, characterized in that: Irregular defects can be outlined by smooth transition, approximating to a circle; where a / h=1 means the defect is exactly tangent to the surface, and a / h>1 means the defect is exposed on the outer surface of the workpiece.
6. The method for quantitatively evaluating the size of microscopic defects in metal materials according to claim 1, characterized in that: The smooth curve transition in step 4 should not have obvious depressions.
7. A method for quantitatively evaluating the size of microscopic defects in metal materials according to claim 1, characterized in that: In the step 1, it is determined that the external load direction / principal stress direction of the defect in the maximum principal stress plane is perpendicular to the paper surface.
8. The method for quantitatively evaluating the size of microscopic defects in metal materials according to claim 1, characterized in that: The size of the microscopic defect for quantitative evaluation is the maximum linear length of the defect outer contour.