A method for rapid hydrogen embrittlement detection of high-strength steel parts for simultaneous two surface treatment processes

Abstract

The present application belongs to the field of aero-engine surface engineering, and particularly relates to a high-strength steel part rapid hydrogen embrittlement detection method for simultaneously performing two surface treatment processes. The method comprises the following steps: first rough machining, and then fine machining to a specified size; processing two notches on the gauge section of the test bar; performing surface treatment on the first notch and its two sides according to one process, and performing surface treatment on the second notch and its two sides according to another process; after heat treatment to eliminate hydrogen embrittlement, clamping the test bar to a testing machine, and performing sustained stretching for 200 hours under a specified load. The present application can solve the problem that different parts of an aero product need to be subjected to two surface treatment processes, and both of the two surface treatment processes need to be subjected to hydrogen embrittlement detection, and the hydrogen embrittlement detection cycle is long. The present application simultaneously performs two surface treatment processes by using one hydrogen embrittlement test bar, instead of using two hydrogen embrittlement test bars for the original two surface treatment processes.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of aero-engine surface engineering, and particularly relates to a rapid hydrogen embrittlement detection method for high-strength steel parts for simultaneously performing two surface treatment processes. BACKGROUND

[0002] A large number of high-strength steels are used in the design and manufacturing process of aero-engines. These steel parts absorb hydrogen in the processes of smelting, hot working, heat treatment and subsequent machining (such as welding, pickling, electroplating, etc.), which causes the mechanical properties of the materials to decrease, crack or be damaged, and is an extremely dangerous failure mode. In order to avoid the hazards caused by hydrogen embrittlement, the high-strength steel needs to be tested for hydrogen embrittlement after chemical treatment. It is generally stipulated that the key parts and important parts with tensile strength exceeding 1300 MPa should be tested for delayed fracture of notched tensile after plating, and the breaking time should be greater than 200 h. In special cases, different parts of some parts need to be treated by two kinds of surface treatment processes respectively, and the hydrogen embrittlement detection needs to be performed for both of the two kinds of surface treatment processes. Therefore, the qualified hydrogen embrittlement detection time exceeds 400 h, and the cycle is long.

[0003] A small amount of hydrogen enters the inside of the steel part in the smelting process of the steel part and the manufacturing and assembly process of the part (such as electroplating, welding), and forms a fracture source under the action of internal residual stress or external applied stress, which causes the material to be embrittled or even cracked. The aero-engine adopts more high-strength steel parts, and in order to improve the corrosion resistance, anti-adhesion and other properties of the parts, chemical treatment such as plating needs to be performed. The plating process can absorb hydrogen, which can cause the material to be hydrogen embrittled and cracked during use. In order to avoid hydrogen embrittlement, the material is generally heated after the chemical treatment process.

[0004] According to the principle of hydrogen embrittlement, the hydrogen embrittlement sensitive notched tensile test bar is used in the field of aviation, and the prescribed load is applied for persistent tension after chemical treatment, so as to evaluate the hydrogen embrittlement tendency of the plating process and the hydrogen embrittlement performance of the plated product. It is generally stipulated that the key parts and important parts with tensile strength exceeding 1300 MPa should be tested for delayed fracture of notched tensile after plating, and the breaking time should be greater than 200 h. At present, the international standard is ASTMF519 (Standard Test Method for Mechanical Hydrogen Embrittlement Evaluation of Plating Coating Processes and Service Environments), and the domestic aviation industry has been implementing HB 5067.1 (Plating Process Hydrogen Embrittlement Test Part 1 Mechanical Method). It is stipulated that one hydrogen embrittlement test bar is used for hydrogen embrittlement test of one surface treatment process, and there is no stipulation on the test method for combined hydrogen embrittlement test of two surface treatment processes. According to the understanding, there is no rapid hydrogen embrittlement test method and related application cases for the hydrogen embrittlement test bar processing and testing unit. SUMMARY

[0005] The present application aims to provide a high-strength steel part rapid hydrogen embrittlement detection method for simultaneously performing two surface treatment processes, solve the problem that different parts of an aviation product need to be subjected to two surface treatment processes, and both of the two surface treatment processes need to be subjected to hydrogen embrittlement detection, and the hydrogen embrittlement detection period is long, and one hydrogen embrittlement test bar is used to simultaneously perform the two surface treatment processes, instead of the original two surface treatment processes which need to use two hydrogen embrittlement test bars.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the present application is:

[0007] A high-strength steel part rapid hydrogen embrittlement detection method for simultaneously performing two surface treatment processes, comprising the following steps:

[0008] Step one, selecting the same material as the product or a material with higher hydrogen embrittlement sensitivity as the test bar material;

[0009] Step two, the test bar is first subjected to rough machining, then subjected to corresponding heat treatment according to the Chinese Aviation Industry Standard HB / Z136 to reach the required tensile strength of the material, and finally machined to the specified size;

[0010] Step three, two notches are machined on the test bar gauge section: a first notch and a second notch, and the part between the first notch and the second notch of the test bar is a transition zone;

[0011] Step four, insulating protection is performed on the second notch and the surfaces on both sides thereof, and surface treatment is performed on the first notch and the surfaces on both sides thereof according to one process;

[0012] Step five, the surface treatment layer completed in step four is subjected to insulating protection, and the insulating protection layer of step four is removed;

[0013] Step six, surface treatment is performed on the second notch and the surfaces on both sides thereof according to another process;

[0014] Step seven, the insulating protection layer on the test bar is removed, and heat treatment is performed to eliminate hydrogen embrittlement;

[0015] Step eight, the test bar is clamped to a testing machine and subjected to sustained tension for 200h under a specified load.

[0016] The high-strength steel part rapid hydrogen embrittlement detection method for simultaneously performing two surface treatment processes, in step two, the feed amount of the test bar machining is 0.02mm-0.01mm at the beginning, and 0.005mm during finishing machining, and the axis of the test bar is parallel to the rolling fiber direction of the material during machining.

[0017] The high-strength steel part rapid hydrogen embrittlement detection method for simultaneously performing two surface treatment processes, in step three, a medium-soft fine-grained alumina grinding wheel is used for grinding.

[0018] The method for simultaneously performing two surface treatment processes on high-strength steel parts, in step four, insulates the surface between the middle of the transition zone on the first side of the second notch and the end of the gauge section on the other side of the second notch, silver-plates the surface between the middle of the transition zone on the first side of the first notch and the end of the gauge section on the other side of the first notch, and makes the silver plating meet the corresponding quality standard.

[0019] The method for simultaneously performing two surface treatment processes on high-strength steel parts, in step five, chemically oxidizes the surface between the middle of the transition zone on the first side of the second notch and the end of the gauge section on the other side of the second notch, and makes the oxide film meet the corresponding quality standard.

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

[0021] 1. The present application innovatively studies a double-notch hydrogen embrittlement test bar, which can represent the hydrogen embrittlement of two surface treatment processes at the same time, and can shorten the test period by half compared with a single-notch hydrogen embrittlement test bar.

[0022] 2. In order to shorten the detection period, the present application innovatively studies a rapid and non-interfering hydrogen embrittlement detection method, which can simultaneously and rapidly detect the hydrogen embrittlement of two surface treatment processes, improve the detection efficiency, and greatly shorten the manufacturing period, from the original at least 400h hydrogen embrittlement test time to 200h, about half of the test time. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figures 1-2 The flowchart of the present application embodiment 1. Among them, Figure 1 is a test bar, Figure 2 is a notch processed on the test bar after heat treatment.

[0024] Figures 3-4 The surface treatment after the present application embodiment 1. Among them, Figure 3 is silver plating, Figure 4 is chemical oxidation.

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

[0026] Next, the operation process of the present application embodiment is described in detail.

[0027] Embodiment 1

[0028] A central drive rod, material grade is 16Cr3NiWMoVNbE, need to carry out silver plating and chemical oxidation process in different parts of the part, tensile strength σb≥1300MPa, hydrogen embrittlement test for silver plating and chemical oxidation, breaking time is greater than 200h.

[0029] In this embodiment, a kind of high-strength steel part rapid hydrogen embrittlement detection method for simultaneously carrying out two surface treatment processes, specific steps are as follows:

[0030] 1, select the diameter of 16Cr3NiWMoVNbE bar material Ф16mm;

[0031] 2, according to Figure 1 Processing test bar, first rough machining, then heat treatment according to Chinese aviation industry standard HB / Z136, reach the tensile strength required by material, finally finish machining to specified size, the feed rate of test bar processing start is 0.02mm-0.01mm, the feed rate is 0.005mm when finish machining, the axis of test bar is parallel to the rolling fiber direction of material during processing;After finish machining, heat treatment is carried out again according to Chinese aviation industry standard HB / Z136, reach the tensile strength required by material;

[0032] 3, as Figure 2 Indicated, after the end of final heat treatment, two notches are processed in test bar 1 gauge section: first notch 2, second notch 4, the part between first notch 2 and second notch 4 of test bar 1 is transition zone 3, medium-soft fine-grained alumina grinding wheel is used, overheating should be avoided, the feed rate should be as small as possible, the notch root radius after grinding is smooth, reaching the final size;

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

[0034] 4, as Figure 3 Indicated, the surface between the middle of transition zone 3 on one side of second notch 4 and one end of gauge section on the other side of second notch 4 is insulated, the surface between the middle of transition zone 3 on one side of first notch 2 and the other end of gauge section on the other side of first notch 2 is silver plated, and the quality of silver plating layer 5 meets the corresponding quality standard;

[0035] 5, the silver plating layer 5 completed in step 4 is insulated, and the insulation layer of step 4 is removed;

[0036] 6, as Figure 4The surface in the transition zone 3 on the side of the second notch 4 to the end of the gauge length on the other side of the second notch 4 is chemically oxidized, and the quality of the oxide film layer 6 meets the corresponding quality standard;

[0037] 7. Removing the insulating protective layer on the test bar 1, and then keeping the test bar 1 at 200 DEG C for 6 hours, and cooling to room temperature in the furnace;

[0038] 8. Clamping the test bar 1 to the testing machine, and enduringly stretching for 200 hours under the specified load.

[0039] The implementation result shows that the application can be applied to steel parts in different positions which need two or more surface treatment processes, can improve the hydrogen embrittlement test efficiency, and shorten the time. According to the original calculation, each kind of surface treatment process needs 6 hydrogen embrittlement test bars each time, and the cost of test bar processing, test bar surface treatment and test bar hydrogen embrittlement test is about 300,000 yuan per year. After adopting the method, the hydrogen embrittlement test bar usage amount can be reduced by half, and 300,000 yuan*1 / 2=150,000 yuan can be saved per year. The technology can reduce the cost, effectively guarantee the service life, reliability and economy, and has a wide market prospect.

Claims

1. A method for rapid hydrogen embrittlement detection of high-strength steel parts subjected to two surface treatment processes simultaneously, characterized in that, Includes the following steps: Step 1: Select the same material as the product or a material with higher hydrogen embrittlement sensitivity as the test rod 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 finished to the specified dimensions. The initial feed rate of the test bar is 0.02mm to 0.01mm, and the final feed rate is 0.005mm. During machining, the axis of the test bar is parallel to the rolling fiber direction of the material. Step 3: Machining two notches in the gauge length section of the test bar: the first notch and the second notch. The part between the first notch and the second notch of the test bar is a transition zone, which is ground with a medium-soft fine-grained alumina grinding wheel. Step 4: Insulate the second notch and its two sides with a protective insulation layer. Perform surface treatment on the first notch and its two sides according to a certain process. Insulate the surface between the middle of the transition area on one side of the second notch and one end of the gauge length section on the other side of the second notch. Plate the surface between the middle of the transition area on one side of the first notch and one end of the gauge length section on the other side of the first notch with silver, and ensure that the quality of the silver plating meets the corresponding quality standards. Step 5: Apply insulation protection to the surface treatment layer completed in Step 4, and then peel off the insulation protection layer from Step 4. Step 6: Perform surface treatment on the second notch and both sides using another process; perform chemical oxidation on the surface between the middle of the transition zone on one side of the second notch and one end of the gauge length on the other side of the second notch, and ensure that the quality of the oxide film layer meets the corresponding quality standards. Step 7: Remove the insulating protective layer on the test rod and perform heat treatment to eliminate hydrogen embrittlement; Step 8: Clamp the test bar onto the testing machine and subject it to a sustained tensile test under the specified load for 200 hours.

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