High-strength steel part rapid hydrogen embrittlement detection method for simultaneously carrying out two surface treatment processes

Abstract

The invention belongs to the field of aero-engine surface engineering, and particularly relates to a rapid hydrogen embrittlement detection method for a high-strength steel part, which is used for simultaneously carrying out two surface treatment processes. The method comprises the following steps: roughly machining a test bar, and then finely machining the test bar to a specified size; two notches are machined in the gauge length section of the test bar, surface treatment is conducted on the first notch and the two sides of the first notch according to one technology, and surface treatment is conducted on the second notch and the two sides of the second notch according to the other technology; after hydrogen embrittlement is eliminated through heat treatment, the test bar is clamped on a testing machine, and the test bar is permanently stretched for 200 h under the specified load. According to the hydrogen embrittlement test bar, the problems that two kinds of surface treatment needs to be carried out on different parts of an aviation product, hydrogen embrittlement detection needs to be carried out on the two kinds of surface treatment, and the hydrogen embrittlement detection period is long can be solved; and two hydrogen embrittlement test bars required by two original surface treatment processes are replaced.

Description

Technical Field

[0001] The invention belongs to the field of aero-engine surface engineering, and in particular relates to a method for quickly detecting hydrogen embrittlement of high-strength steel parts for simultaneously performing two surface treatment processes. Background Art

[0002] A large amount of high-strength steel is used in the design and manufacturing process of aircraft engines. These steel parts absorb hydrogen during smelting, hot working, heat treatment and subsequent mechanical processing (such as welding, pickling, electroplating, etc.), causing the mechanical properties of the material to deteriorate, crack or be damaged, which is an extremely dangerous failure mode. In order to avoid the hazards caused by hydrogen embrittlement, high-strength steel needs to be tested for hydrogen embrittlement after chemical treatment. It is generally stipulated that after the key parts and important parts with a tensile strength exceeding 1300MPa are plated, a notch tensile delayed failure test should be carried out, and the breaking time should be greater than 200h. In special cases, different parts on some parts need to undergo two surface treatment processes respectively, and both surface treatment processes require hydrogen embrittlement detection. Therefore, the qualified hydrogen embrittlement detection time exceeds 400h, which is a long cycle.

[0003] During the smelting process of steel parts and the manufacturing and assembly process of parts (such as electroplating and welding), trace amounts of hydrogen that enter the interior of the steel parts form fracture sources under the action of internal residual or external stress, causing the material to become brittle or even crack. Aircraft engines use a large number of high-strength steel parts. In order to improve the corrosion resistance and anti-adhesion properties of the parts, chemical treatments such as plating are required. The plating process will absorb hydrogen, which will cause hydrogen embrittlement fracture of the material during use. To avoid hydrogen embrittlement, heating treatment is generally performed after the chemical treatment process.

[0004] In the aviation field, based on the principle of hydrogen embrittlement, notched tensile test bars that are sensitive to hydrogen embrittlement are used. After chemical treatment, a specified load is applied for sustained stretching to evaluate the hydrogen embrittlement tendency of the plating process and the hydrogen embrittlement performance of the plated product. It is generally stipulated that after the key parts and important parts with a tensile strength exceeding 1300MPa are plated, a notched tensile delayed failure test should be carried out, and the breaking time should be greater than 200h. At present, ASTMF519 (Standard Test Method for Mechanical Hydrogen Embrittlement Evaluation of Plating Coating Processes and Service Environments) is implemented internationally, and the domestic aviation industry has been implementing HB 5067.1 (Mechanical Method for Hydrogen Embrittlement Test of Plating Process Part 1), which stipulates that a hydrogen embrittlement test bar is used for hydrogen embrittlement test of one surface treatment process, and there is no test method for combining hydrogen embrittlement tests of two surface treatment processes. It is understood that the hydrogen embrittlement test bar processing and testing units currently do not have rapid hydrogen embrittlement test methods and related application cases. Summary of the invention

[0005] The purpose of the present invention is to provide a method for rapid hydrogen embrittlement detection of high-strength steel parts for simultaneously performing two surface treatment processes, so as to solve the problem that different parts of aviation products need to undergo two surface treatment processes, and both surface treatment processes require hydrogen embrittlement detection, and the hydrogen embrittlement detection cycle is long. One hydrogen embrittlement test rod is used to simultaneously perform two surface treatment processes, instead of the original two surface treatment processes requiring the use of two hydrogen embrittlement test rods.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] A method for rapid hydrogen embrittlement detection of high-strength steel parts for simultaneously undergoing two surface treatment processes comprises the following steps:

[0008] Step 1: Select the same material as the product or a material with higher hydrogen embrittlement sensitivity as the test bar material;

[0009] Step 2: The test bar is first rough-machined, then heat-treated according to the Chinese aviation industry standard HB / Z136 to achieve the required tensile strength of the material, and finally fine-machined to the specified size;

[0010] Step 3: Process two notches in the gauge section of the test rod: a first notch and a second notch, and the portion between the first notch and the second notch of the test rod is a transition zone;

[0011] Step 4: Insulate and protect the second notch and the surfaces on both sides thereof, and perform surface treatment on the first notch and the surfaces on both sides thereof according to a process;

[0012] Step 5, insulating the surface treatment layer completed in step 4, and peeling off the insulating protection layer in step 4;

[0013] Step 6: Performing surface treatment on the second notch and both sides thereof according to another process;

[0014] Step 7: Remove the insulating protective layer on the test rod and perform heat treatment to eliminate hydrogen embrittlement;

[0015] Step 8. Clamp the test rod onto the testing machine and stretch it for 200 hours under the specified load.

[0016] In the method for rapid hydrogen embrittlement detection of high-strength steel parts for simultaneously performing two surface treatment processes, in step 2, the test rod processing feed amount is 0.02mm-0.01mm at the beginning and 0.005mm during fine processing. During processing, the test rod axis is parallel to the rolling fiber direction of the material.

[0017] In the method for rapid hydrogen embrittlement detection of high-strength steel parts for simultaneously performing two surface treatment processes, in step three, grinding is performed using a medium-soft fine-grained alumina grinding wheel.

[0018] In the method for rapid hydrogen embrittlement detection of high-strength steel parts for simultaneously performing two surface treatment processes, in step four, the surface between the middle of the transition zone on one side of the second notch and one end of the gauge section on the other side of the second notch is insulated and protected, and the surface between the middle of the transition zone on one side of the first notch and the other end of the gauge section on the other side of the first notch is silver-plated, and the quality of the silver plating meets the corresponding quality standards.

[0019] In the method for rapid hydrogen embrittlement detection of high-strength steel parts for simultaneously performing two surface treatment processes, in step five, chemical oxidation is performed on the surface between the middle of the transition zone on one side of the second notch and one end of the gauge section on the other side of the second notch, and the quality of the oxide film layer meets the corresponding quality standards.

[0020] Compared with the prior art, the present invention has the following main advantages and beneficial effects:

[0021] 1. The present invention innovatively studies a double-notch hydrogen embrittlement test bar, which can simultaneously characterize the hydrogen embrittlement of two surface treatment processes. Compared with the single-notch hydrogen embrittlement test bar, it can shorten the test cycle, basically shortening the time by half.

[0022] 2. In order to shorten the detection cycle, the present invention innovatively studies a rapid and non-interference hydrogen embrittlement detection method, which can simultaneously and rapidly detect the hydrogen embrittlement of two surface treatment processes, improve the detection efficiency, and significantly shorten the manufacturing cycle. The original hydrogen embrittlement test time of at least 400 hours is shortened to 200 hours, which is about half the test time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1-Figure 2 This is a flow chart of Example 1 of the present invention. Figure 1 To process the test bar, Figure 2 To machine a notch on the test bar after heat treatment.

[0024] Figure 3-Figure 4 This is a surface treatment diagram of Example 1 of the present invention. Figure 3 For silver plating, Figure 4 It is chemical oxidation.

[0025] In the figure, 1 is a test rod, 2 is a first notch, 3 is a transition zone, 4 is a second notch, 5 is a silver coating, and 6 is an oxide film. DETAILED DESCRIPTION

[0026] The operation process of the embodiment of the present invention is described in detail below.

[0027] Example 1

[0028] A central transmission rod, with a material grade of 16Cr3NiWMoVNbE, needs to undergo silver plating and chemical oxidation processes at different locations of the part. The tensile strength σb is ≥ 1300MPa. Hydrogen embrittlement tests are performed on silver plating and chemical oxidation, and the breaking time is greater than 200h.

[0029] In this embodiment, a method for rapid hydrogen embrittlement detection of high-strength steel parts for simultaneously performing two surface treatment processes is provided, and the specific steps are as follows:

[0030] 1. Select 16Cr3NiWMoVNbE bar with a diameter of Ф16mm;

[0031] 2. According to Figure 1 The test bar is processed by rough machining first, then heat treatment according to the Chinese aviation industry standard HB / Z136 to achieve the required tensile strength of the material, and finally fine machining to the specified size. The feed amount of the test bar processing is 0.02mm~0.01mm at the beginning, and the feed amount during fine machining is 0.005mm. During processing, the axis of the test bar is parallel to the rolling fiber direction of the material; after fine machining, heat treatment is performed according to the Chinese aviation industry standard HB / Z136 to achieve the required tensile strength of the material;

[0032] 3. If Figure 2 As shown in the figure, after the final heat treatment, two notches are machined in the gauge section of the test bar 1: the first notch 2 and the second notch 4. The portion between the first notch 2 and the second notch 4 of the test bar 1 is a transition zone 3. A medium-soft fine-grained alumina grinding wheel is used for grinding. Overheating should be avoided, and the feed amount should be as small as possible. The root radius of the notch after grinding is smooth and reaches the final size.

[0033] In this embodiment, medium-soft fine-grained alumina refers to alumina with a smaller particle size and a softer texture. According to the particle size classification, the particle size of medium-soft fine-grained alumina is usually below 45 microns, and the average particle size is between 50 and 80 microns. The feed amount during grinding is 0.005mm to 0.01mm, and the root radius of the notch after grinding is 0.11 to 0.13mm;

[0034] 4. If Figure 3 As shown, the surface between the middle of the transition zone 3 on one side of the second notch 4 and one end of the gauge section on the other side of the second notch 4 is insulated and protected, and the surface between the middle of the transition zone 3 on one side of the first notch 2 and the other end of the gauge section on the other side of the first notch 2 is silver-plated, and the quality of the silver plating layer 5 meets the corresponding quality standards;

[0035] 5. Insulate and protect the silver-plated layer 5 completed in step 4, and peel off the insulating protective layer of step 4;

[0036] 6. If Figure 4As shown, chemical oxidation is performed on the surface between the middle of the transition zone 3 on one side of the second notch 4 and one end of the gauge section on the other side of the second notch 4, and the quality of the oxide film layer 6 meets the corresponding quality standards;

[0037] 7. Remove the insulating protective layer on the test rod 1, then keep the test rod 1 at 200°C for 6 hours and cool it to room temperature with the furnace;

[0038] 8. Clamp the test bar 1 onto the testing machine and stretch it for 200 hours under the specified load.

[0039] The implementation results show that the present invention can be applied to steel parts that require two or more surface treatment processes at different locations to improve the efficiency of hydrogen embrittlement testing and shorten the time. According to the original calculation that each surface treatment process requires 6 hydrogen embrittlement test bars each time, and the annual cost of test bar processing, test bar surface treatment, and test bar hydrogen embrittlement testing is about 300,000 yuan, the use of this method can reduce the use of hydrogen embrittlement test bars by half, and can save 300,000 yuan × 1 / 2 = 150,000 yuan each year. This technology can reduce costs, effectively guarantee its life, reliability and economy, and has broad market prospects.

Claims

1. A method for rapid hydrogen embrittlement detection of high-strength steel parts for simultaneously performing two surface treatment processes, characterized in that: The following steps are involved: Step 1: Select the same material as the product or a material with higher hydrogen embrittlement sensitivity as the test bar material; Step 2: The test bar is first rough-machined, then heat-treated according to the Chinese aviation industry standard HB / Z136 to achieve the required tensile strength of the material, and finally fine-machined to the specified size; Step 3: Process two notches in the gauge section of the test rod: a first notch and a second notch, and the portion between the first notch and the second notch of the test rod is a transition zone; Step 4: Insulate and protect the second notch and the surfaces on both sides thereof, and perform surface treatment on the first notch and the surfaces on both sides thereof according to a process; Step 5, insulating the surface treatment layer completed in step 4, and peeling off the insulating protection layer in step 4; Step 6: Performing surface treatment on the second notch and both sides thereof according to another process; Step 7: Remove the insulating protective layer on the test rod and perform heat treatment to eliminate hydrogen embrittlement; Step 8. Clamp the test rod onto the testing machine and stretch it for 200 hours under the specified load.

2. The method for rapid hydrogen embrittlement detection of high-strength steel parts for simultaneously performing two surface treatment processes according to claim 1, characterized in that: In step 2, the test rod processing feed amount is 0.02mm-0.01mm at the beginning and 0.005mm during fine processing. During processing, the test rod axis is parallel to the rolling fiber direction of the material.

3. The method for rapid hydrogen embrittlement detection of high-strength steel parts for simultaneously performing two surface treatment processes according to claim 1, characterized in that: In step three, grinding is performed using a medium-soft fine-grained aluminum oxide grinding wheel.

4. The method for rapid hydrogen embrittlement detection of high-strength steel parts for simultaneously performing two surface treatment processes according to claim 1, characterized in that: In step four, the surface between the middle of the transition zone on one side of the second notch and one end of the gauge section on the other side of the second notch is insulated and protected, and the surface between the middle of the transition zone on one side of the first notch and the other end of the gauge section on the other side of the first notch is silver-plated, and the quality of the silver plating meets the corresponding quality standards.

5. The method for rapid hydrogen embrittlement detection of high-strength steel parts for simultaneously performing two surface treatment processes according to claim 4, characterized in that: In step five, chemical oxidation is performed on the surface between the middle of the transition zone on one side of the second notch and one end of the gauge section on the other side of the second notch, and the quality of the oxide film layer meets the corresponding quality standards.

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