A method for rapid inspection of blue fracture of high carbon chromium bearing steel

Abstract

The present invention discloses a method for rapid inspection of blued fracture of high carbon chromium bearing steel, belonging to the technical field of steel detection. The method for rapid inspection of blued fracture of high carbon chromium bearing steel of the present invention comprises the steps of blueing treatment: placing the broken sample slice into a heat treatment furnace heated to 530℃~550℃, observing the blueing of the grooved fracture of the sample slice, and taking out the sample slice; different from the prior art heat preservation treatment process of 300℃~350℃ which takes 2~3 hours, the present invention adopts heat treatment of 530℃~550℃ according to the special component composition of high carbon chromium bearing steel, and can quickly obtain good and clear blued fracture structure, which takes minutes, and the detection is fast and accurate. It solves the problem that the fracture blueing takes a long time in the existing steel detection, and the cross section is easily contaminated due to the influence of the oxidizing atmosphere in the furnace.

Description

Technical Field

[0001] The invention belongs to the technical field of steel material detection, and more specifically relates to a method for rapid detection of blue fracture of high-carbon chromium bearing steel. Background Art

[0002] Fracture blueing is a common method for detecting macroscopic inclusions in steel. The broken specimen is blued in a resistance furnace, and a blue oxide film is formed on the metal matrix of the fracture at the blue brittle temperature, while the non-metallic inclusions do not oxidize and maintain their original color, usually in the form of non-crystalline strips such as grayish white, light yellow or yellow-green.

[0003] The current inspection standards for blue fracture in various countries include: ISO 3763-1976, SKFD30, SEP1584, GB / T37598-2019, GB / T 18254-2016, etc. The description of the bluing treatment process is that the sample is heated to 300℃~350℃ and kept warm for a period of time, and a blue oxide film can be formed on the fracture.

[0004] In the existing fracture blueing detection, the cross section is easily contaminated by the oxidizing atmosphere in the furnace, which will lead to uneven blue color of the cross section during blueing. In addition, the operation time is difficult to control and generally takes 2 to 3 hours.

[0005] After searching, the application case with Chinese patent application number 201510565595.X discloses a simple and feasible blue fracture inspection method, which includes the following steps: 1. Cut the sample from the forged bar, rolled billet or equivalent billet and make a groove. The length of the sample cut from the steel with a diameter of ≤50mm is 100mm, and the groove is cut on the side wall of the sample. The thickness of the sample cut from the steel with a diameter in the range of 50mm to 100mm is 15-20mm, and the center groove is cut through the cross section of the sample; 2. Keep the sample with the groove at its austenitizing temperature for a period of time, and then quench and temper it; 3. Break the sample once; 4. Cool the broken sample naturally in the air. The benefits of this invention are: the heat treatment process is simple and feasible, and the sample does not need to add a blueing process; the inspection section is cleaner, the blueing color is uniform, and the inclusion distribution detection effect is clear and visible. However, the invention still takes hours and is greatly affected by the oxidizing atmosphere in the furnace. Summary of the invention

[0006] 1. Problems to be solved

[0007] In view of the problem that the blueing process of the fracture surface takes a long time during the existing steel inspection and the fracture surface is easily contaminated due to the influence of the oxidizing atmosphere in the furnace, the present invention provides a method for quickly inspecting the blued fracture surface of high-carbon chromium bearing steel. In view of the special component composition of high-carbon chromium bearing steel, high-temperature treatment in a heat treatment furnace at 530°C to 550°C is adopted to quickly obtain a good and clear blued fracture surface structure, and the distribution of macroscopic inclusion content in the steel can be accurately evaluated.

[0008] 2. Technical solution

[0009] In order to solve the above problems, the technical solution adopted by the present invention is as follows:

[0010] The invention discloses a method for rapid inspection of blue fracture of high carbon chromium bearing steel, comprising the steps of blueing treatment: placing the broken sample slice into a heat treatment furnace heated to 530°C to 550°C, observing the blueing of the groove surface fracture of the sample slice, and then taking out the sample slice; different from the prior art that the heat preservation treatment process of 300°C to 350°C takes 2 to 3 hours, the present scheme adopts heat treatment of 530°C to 550°C according to the special component composition of high carbon chromium bearing steel, and can quickly obtain a good and clear blue fracture structure, which takes minutes, and the detection is fast and accurate. The technical principle is: the oxidation reaction of steel with oxygen in a high temperature environment is called high temperature oxidation. High temperature oxidation can generate three oxides: FeO, Fe2O3, and Fe3O4. When the temperature is below 570°C, the oxide film is mainly composed of Fe2O3 and Fe3O4; when the temperature is higher than 570°C, the oxide film is composed of FeO, Fe2O3, and Fe3O4. Fe2O3 and Fe3O4 have a dense structure, can protect the metal surface, and have good anti-oxidation. The anti-oxidation ability of FeO is very poor. When the temperature is higher than 500°C, the high-temperature oxidation process tends to accelerate, and the inventors have found that the chromium element in the high-carbon chromium bearing steel generates an oxide film with good protective effect, which can better prevent overoxidation and give a certain operating space for high-temperature oxidation treatment. The Fe2O3 formed at high temperature (about 550°C) is sky blue. During the test process of the present invention, different temperatures of 500°C to 570°C are used for testing, and it is concluded that within the temperature range of 530°C to 550°C, the blue oxide film formed on the fracture surface is fast in efficiency and high in quality.

[0011] Preferably, the bluing treatment step has a treatment time of 3 to 7 minutes. If it is too long, it will result in excessive oxidation, affecting the quality of the blue film, while if it is too short, the film will be darker in color.

[0012] Preferably, the specific steps are:

[0013] Step 1: Sampling: Take the high carbon chromium bearing steel sample after rolling, and cross-cut it to obtain slices;

[0014] Step 2: Groove: On the center line of the slice cross section, a groove is carved through the axis;

[0015] Step 3: Break: Place the cut surface of the sample with the groove facing downward on the support table of the fracture machine or pressure testing machine, so that the impact blade coincides with the center line of the sample groove, and break the slice at one time under the impact load or pressure;

[0016] Step 4: the bluing step.

[0017] Preferably, the slice thickness is 15 mm to 20 mm, and the remaining slice thickness after the grooves are carved is not less than 10 mm, that is, the groove depth is 5 mm to 10 mm, so as to ensure a neat cross section.

[0018] Preferably, the groove is a V-shaped groove, and the bottom of the groove should be as sharp as possible to ensure that the slice is broken in one go.

[0019] Preferably, the method further comprises an observation step: observing the blue fracture sample with naked eyes or a magnifying glass no greater than 10 times, and recording the distribution of non-metallic inclusions on the blue fracture surface. The operation is simple, convenient and quick.

[0020] Preferably, in the bluing step, the furnace door is opened to immediately observe the treatment status of the groove surface fracture. Compared with the prior art, conventional bluing treatment requires a closed heating furnace, and the higher the high temperature, the more difficult it is to control the test. In order to improve the oxidation capacity of the environment and facilitate operation and observation, the furnace door is opened under the temperature conditions of the present scheme, so that the treatment status of the sample can be immediately observed. The operability is high, and a blue film can be quickly formed at the fracture within 3 to 7 minutes, which greatly improves the inspection efficiency.

[0021] Preferably, it is suitable for the special component composition of high carbon chromium bearing steel produced in GB / T 18254-2016, especially GCr15 steel.

[0022] 3. Beneficial effects

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) Compared with the inspection method in the prior art, the bluing treatment process of the high carbon chromium bearing steel by the present invention is simple and controllable, and a blue film can be quickly formed at the fracture, which greatly improves the inspection efficiency;

[0025] (2) In the inspection process of the present invention, the temperature range of 530°C to 550°C is used, and the oxidation blue film formed on the fracture surface is efficient and has high quality;

[0026] (3) Under the temperature conditions of the present invention, the furnace door is opened, and the processing status of the sample can be observed at all times. The operability is high, and a blue film can be quickly formed at the fracture within 3 to 7 minutes, which greatly improves the inspection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the structure of cutting and grooving a sample in the present invention;

[0028] Figure 2 It is a schematic diagram of the state of the fracture of the groove surface after the slice is broken in the present invention;

[0029] Figure 3 This is a photo of the comparative example after the groove surface failed to blue.

[0030] Figure 4 This is a photo of the groove surface of Example 2 after blueing treatment;

[0031] Figure 5 This is a photograph of the groove surface of Example 3 after blueing treatment.

[0032] In the figure: 1. Slicing; 2. Notching; 3. Fracture of the notched surface; 4. Specimen. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with specific embodiments.

[0034] Example 1

[0035] The method for rapid inspection of blue fracture of high carbon chromium bearing steel in this embodiment comprises the following specific steps:

[0036] Step 1, sampling: taking a high carbon chromium bearing steel sample 4 after rolling, the most commonly used high carbon chromium bearing steel is GCr15 steel or GCr15SiMn steel, and cross-cutting it to obtain a slice 1;

[0037] Step 2: Groove: On the center line of the cross section of slice 1, groove 2 is carved through the axis;

[0038] Step 3, breaking: Place the slot 2 with the grooved surface facing downward on the support table of the fracture machine or pressure testing machine, so that the impact blade coincides with the center line of the sample groove, and break the slice 1 at one time under the impact load or pressure;

[0039] Step 4: bluing treatment: Place the broken sample slice 1 in a heat treatment furnace heated to 530° C. to 550° C., and after observing that the groove surface 3 of the sample slice 1 turns blue, take out the sample slice 1.

[0040] The method for rapid inspection of bluing fracture of high carbon chromium bearing steel in this embodiment has a simple bluing process and strong controllability. A blue film can be quickly formed at the fracture, and the formed oxidized blue film is efficient and of high quality, which greatly improves the inspection efficiency.

[0041] Example 2

[0042] The method for rapid inspection of blue fracture of high carbon chromium bearing steel in this embodiment comprises the following specific steps:

[0043] Step 1, sampling: Take the rolled high carbon chromium bearing steel sample 4, select the most commonly used GCr15SiMn steel in high carbon chromium bearing steel, a bar with a diameter of 80 mm, and cross-cut it to obtain a slice 1, the thickness of the slice 1 is 15 mm to 20 mm.

[0044] Step 2: Groove: Figure 1 As shown, a groove 2 is carved through the axis on the center line of the cross section of the slice 1; the thickness of the remaining slice 1 after the groove 2 is carved is not less than 10 mm, that is, the depth of the groove 2 is 5 mm to 10 mm, so as to ensure a neat cross section; the groove 2 is a V-shaped groove, and in order to ensure that the slice 1 is broken at one time, the bottom of the groove should be as sharp as possible;

[0045] Step 3: Break: Place the slot 2 with the grooved surface facing downward on the support table of the fracture machine or pressure testing machine, so that the impact blade coincides with the center line of the sample groove. Under the impact load or pressure, break the slice 1 into two grooved surface fractures 3 at one time, as shown in the following figure. Figure 2 The state of the groove surface fracture 3 after the slice 1 is broken shown;

[0046] Step 4: bluing treatment: Place the broken sample slice 1 in a heat treatment furnace heated to 530°C to 550°C, open the furnace door, and immediately observe the treatment of the groove surface fracture 3. After observing that the groove surface fracture 3 of the sample slice 1 is bluing, generally, a blue film can be quickly formed in 3 to 7 minutes, and then take out the sample slice 1;

[0047] Step 5. Observation: Observe the blue fracture specimen with the naked eye or a magnifying glass no greater than 10 times, and record the distribution of non-metallic inclusions on the blue fracture surface. Figure 4 As shown, the operation is simple, convenient and fast.

[0048] Example 3

[0049] The method for rapid inspection of blue fracture of high carbon chromium bearing steel in this embodiment comprises the following specific steps:

[0050] Step 1, sampling: Take the high carbon chromium bearing steel sample 4 after rolling, select the most commonly used GCr15 steel in high carbon chromium bearing steel, a bar with a diameter of 80 mm, and cross-cut it to obtain a slice 1, the thickness of the slice 1 is 15 mm to 20 mm.

[0051] Step 2, groove cutting: on the center line of the cross section of slice 1, groove 2 is cut through the axis; after the groove 2 is cut, the thickness of the remaining slice 1 is not less than 10mm, that is, the depth of groove 2 is 5mm to 10mm, so as to ensure that the cross section is neat; groove 2 is a V-shaped groove, and in order to ensure that slice 1 is broken at one time, the bottom of the groove should be as sharp as possible;

[0052] Step 3, breaking: Place the slot 2 with the grooved surface facing downward on the support table of the fracture machine or pressure testing machine, so that the impact blade coincides with the center line of the sample groove, and break the slice 1 at one time under the impact load or pressure;

[0053] Step 4: bluing treatment: Place the broken sample slice 1 in a heat treatment furnace heated to 530°C to 550°C, open the furnace door, and immediately observe the treatment of the groove surface fracture 3. After the groove surface fracture 3 of the sample slice 1 is observed to be bluing, generally, a blue film can be quickly formed in 3 to 7 minutes, and then take out the sample slice 1;

[0054] Step 5. Observation: Observe the blue fracture specimen with the naked eye or a magnifying glass no greater than 10 times, and record the distribution of non-metallic inclusions on the blue fracture surface. Figure 5 As shown, the operation is simple, convenient and fast.

[0055] Comparative Example

[0056] The method for rapid inspection of the blue fracture of the high carbon chromium bearing steel in this comparative example comprises the following specific steps:

[0057] Step 1, sampling: Take the high carbon chromium bearing steel sample 4 after rolling, select the most commonly used GCr15 steel in high carbon chromium bearing steel, a bar with a diameter of 80 mm, and cross-cut it to obtain a slice 1, the thickness of the slice 1 is 15 mm to 20 mm.

[0058] Step 2, groove cutting: on the center line of the cross section of slice 1, groove 2 is cut through the axis; after the groove 2 is cut, the thickness of the remaining slice 1 is not less than 10mm, that is, the depth of groove 2 is 5mm to 10mm, so as to ensure that the cross section is neat; groove 2 is a V-shaped groove, and in order to ensure that slice 1 is broken at one time, the bottom of the groove should be as sharp as possible;

[0059] Step 3, breaking: Place the slot 2 with the grooved surface facing downward on the support table of the fracture machine or pressure testing machine, so that the impact blade coincides with the center line of the sample groove, and break the slice 1 at one time under the impact load or pressure;

[0060] Step 4: bluing treatment: placing the broken sample slice 1 in a heat treatment furnace heated to 300°C to 350°C in a closed heating furnace, and taking out the sample slice 1 after 3 to 7 minutes;

[0061] Step 5. Observation: Observe the blue fracture surface sample with naked eyes or a magnifying glass no greater than 10 times, and record the blue fracture surface. Figure 3 shown.

[0062] Combined with the specific detection steps of Examples 2, 3 and Comparative Examples and the attached Figures 3 to 5 ,like Figure 4 As shown, in the scheme of Example 2, the GCr15SiMn steel is bluing treated to form a fracture morphology with a lighter sky blue color (because the pictures in the patent application are not allowed to have colors, they are displayed in gray, and the actual color is light blue); Figure 3 As shown in the figure, under the conventional treatment method of the comparative example, due to the short duration, the fracture morphology of the failed case did not form a blue fracture; Figure 5 As shown, the grooved surface fracture 3 formed by the GCr15 steel of Example 3 is a darker deep sky blue (because the pictures in the patent application do not allow color, they are displayed in black, and the actual color is deep sky blue), and the bluing treatment effect is the best, indicating that the method for rapid inspection of bluing fracture of high carbon chromium bearing steel of the present invention is preferentially applicable to GCr15 steel among high carbon chromium bearing steels.

[0063] The present invention and its embodiments are described schematically above, and the description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by it and designs a structural method and an embodiment similar to the technical solution without creativity without departing from the purpose of the invention, they shall all fall within the protection scope of the present invention.

Claims

1. A method for rapid inspection of blue fracture of high carbon chromium bearing steel, characterized by: The method is applicable to high carbon chromium bearing steel produced in accordance with GB / T 18254-2016; comprising the steps of bluing treatment: placing the broken sample slice (1) in a heat treatment furnace heated to 530°C to 550°C, observing that the groove surface fracture (3) of the sample slice (1) is bluing, and then taking out the sample slice (1); The bluing treatment step takes 3 to 7 minutes.

2. The method for rapid inspection of blue fracture of high carbon chromium bearing steel according to claim 1, characterized in that: The specific steps are: Step 1, sampling: taking a high carbon chromium bearing steel sample (4) after rolling, and cross-cutting it to obtain a slice (1); Step 2: Grooving: On the center line of the cross section of the slice (1), a groove (2) is carved through the axis; Step 3, breaking: Place the slotted (2) with the grooved surface facing downward on the support table of the fracture machine or pressure testing machine, so that the impact blade coincides with the center line of the sample groove, and break the slice (1) at one time under the impact load or pressure; Step 4: the bluing step.

3. The method for rapid inspection of blue fracture of high carbon chromium bearing steel according to claim 2, characterized in that: The thickness of the remaining slice (1) after the groove (2) is carved is not less than 10 mm.

4. The method for rapid inspection of blue fracture of high carbon chromium bearing steel according to claim 2, characterized in that: The slice (1) has a thickness of 15 mm to 20 mm.

5. The method for rapid inspection of blue fracture of high carbon chromium bearing steel according to claim 2, characterized in that: The groove (2) is a V-shaped groove.

6. The method for rapid inspection of blue fracture of high carbon chromium bearing steel according to any one of claims 1 to 5, characterized in that: It also includes an observation step: observing the blue fracture specimen with the naked eye or a magnifying glass no larger than 10 times, and recording the distribution of non-metallic inclusions on the blue fracture surface.

7. The method for rapid inspection of blue fracture of high carbon chromium bearing steel according to claim 6, characterized in that: In the bluing step, the furnace door is opened to instantly observe the treatment status of the groove surface fracture (3).

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