CN115356200A - Oil well pipe hydrogen sulfide stress corrosion resistance sensitivity testing method based on fracture sample - Google Patents
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Abstract
The invention provides a method for testing the hydrogen sulfide stress corrosion resistance sensitivity of an oil well pipe based on a fracture sample, which comprises the following steps: processing a sample into a set size, and pretreating the surface of the sample; mounting the sample on a stretching device in a reaction kettle, adding a proper amount of test solution into the reaction kettle, and sealing the reaction kettle; adjusting the concentration of hydrogen sulfide in the test solution, and quickly stretching and preloading the hydrogen sulfide to a 70-80% yield strength value of the test sample; after the preloading is stable, starting to perform a slow tensile loading test at a set strain rate until the test sample is broken, and recording a test result; and taking out the fractured tensile sample, removing corrosion products on the surface of the sample and on the fracture, and evaluating the stress corrosion resistance of the oil well pipe material through fracture morphology observation and step crack parameters. The slow tensile test result is accurately analyzed by utilizing the step crack parameters on the fracture, so that the aim of quantitatively analyzing the stress corrosion resistance sensitivity of the oil well pipe material is fulfilled, the test period is shortened, and the detection efficiency is improved.
Description
Technical Field
The invention relates to the technical field of corrosion tests, in particular to a method for testing the stress corrosion sensitivity of an oil well pipe to hydrogen sulfide based on a fracture sample.
Background
In recent years, with the exploration and development of oil and gas wells in ultra-deep, ultra-high temperature and ultra-high corrosion harsh environments, the working condition environment of the oil and gas wells generally has the characteristics of high temperature, high pressure, high CO2, high H2S, high Cl and high salinity, and the stress corrosion cracking failure of oil well pipes is caused by the complex and harsh working conditions and the special operation process, so that the normal production and operation of oil and gas fields are seriously influenced. In particular, in the exploration and exploitation process of sulfur-containing oil and gas resources, the used oil well pipe is easy to generate hydrogen sulfide stress corrosion cracking, which is low-stress brittle fracture, the crack propagation speed is high, the fracture has burstiness, the risk coefficient is highest, and major accidents and casualties are easy to cause.
In view of the above situation, relevant standards are established at home and abroad to reduce the risk caused by hydrogen Sulfide Stress Corrosion Cracking (SSCC), and the SSCC resistance of the oil well pipe is strictly detected and evaluated. Standard tensile tests (method A) are specified in NACE Standard (TM) 0177-2005 indoor tests for metal sulfide stress corrosion cracking resistance and stress corrosion cracking resistance in H2S environment and GB/T4157-2006 laboratory tests for metal special form environmental cracking resistance in hydrogen sulfide environment, the hydrogen sulfide stress corrosion resistance performance is determined by the fracture time in the experimental period, products which do not fracture after exceeding 720H are qualified, products which fracture within 720H are unqualified, and the test result can only give out failure and non-failure information. Similarly, a four-point bending loading test in the ASTM G39-99 standard is also a common method for evaluating the stress corrosion resistance of the oil well pipe, a standard solution of the method A is adopted, a product which is not broken within 720h is qualified, a product which is broken within 720h is unqualified, whether cracks exist on the surface of a sample which is not broken is observed by a magnifying lens of 10 times, and the test result can only give out failure and non-failure information. The methods have the defects of harsh test conditions, long test period, qualified and unqualified test results and other related information, the hydrogen sulfide stress corrosion resistance grade of an ineffectiveness-free sample cannot be evaluated, other test means are required to be combined for comprehensive evaluation, the test period is prolonged, and the test cost is increased.
Therefore, a new method is needed to be found, which can quickly and accurately evaluate the hydrogen sulfide stress corrosion resistance of the oil well pipe material, shorten the test period and reduce the test cost. The slow-rate tensile test is fast, accurate, high in reproducibility, and has a lot of obtained parameter information, so that the slow-rate tensile test is widely used by extensive researchers, and is one of the mature and advanced standard methods for researching stress corrosion at present. When the hydrogen sulfide stress corrosion resistance of the oil well pipe is evaluated by a slow tensile test, fracture morphology and stress corrosion cracking sensitivity index are generally adopted for evaluation, and if the fracture morphology is a brittle fracture characteristic or the stress corrosion cracking sensitivity index is larger than a certain value (generally 25%), the oil well pipe material is generally considered to have stress corrosion cracking sensitivity in a corresponding research system.
However, in the actual test process, the fracture morphology is often found to be a ductile fracture or mixed fracture mechanism, the stress corrosion sensitivity index calculated by using the elongation after fracture, the shrinkage after fracture and the yield strength loss ratio is lower than 25%, the material is generally considered to have no stress corrosion sensitivity, but a stepped crack platform appears near the fracture circumference, which indicates that the material actually has obvious stress corrosion sensitivity, and the stress corrosion sensitivity is not in accordance with the test result. In addition, even if two materials with the same stress corrosion sensitivity index have different actual stress corrosion resistance, particularly, crack steps perpendicular to the stretching direction in the fracture morphology are distributed along the circumferential direction, and the size and the number of the crack steps are obviously different, so that the SSCC resistance of the materials is not easy to accurately evaluate.
Based on the above, the invention is especially provided for accurately and quickly evaluating the hydrogen sulfide stress corrosion resistance of the oil well pipe material.
Disclosure of Invention
In order to overcome the defects in the background art, the invention provides a method for testing the hydrogen sulfide stress corrosion resistance sensitivity of an oil well pipe based on a fracture sample, which can quickly and accurately evaluate the hydrogen sulfide stress corrosion resistance of an oil well pipe material, and can accurately analyze the slow tensile test result by using the step crack parameters on the fracture, thereby achieving the purpose of quantitatively analyzing the stress corrosion resistance sensitivity of the oil well pipe material, shortening the test period and improving the detection efficiency.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for testing the hydrogen sulfide stress corrosion resistance sensitivity of an oil well pipe based on a fracture sample comprises the following steps:
step 1: processing a sample into a set size, and pretreating the surface of the sample;
step 2: mounting the sample on a stretching device in a reaction kettle, adding a proper amount of test solution into the reaction kettle, and sealing the reaction kettle;
and 3, step 3: adjusting the concentration of hydrogen sulfide in the test solution, and quickly stretching and preloading the hydrogen sulfide to 70-80% yield strength value of the test sample;
and 4, step 4: after the preloading is stable, starting to perform a slow tensile loading test at a set strain rate until the test sample is broken, and recording a test result;
and 5: and finally, taking out the fractured tensile sample, removing corrosion products on the surface of the sample and on the fracture, and evaluating the stress corrosion resistance of the oil well pipe material through fracture morphology observation and step crack parameters.
Further, the strain rate of the slow tensile loading test is 1 × 10 -7 ～5×10 -5 mm/s。
Further, the strain rate of the rapid stretching is more than or equal to 1 × 10 -4 mm/s。
Further, the evaluating the stress corrosion resistance of the oil well pipe material in the step 5 specifically comprises the following steps:
1) The crack propagation direction is along the step crack plane, and the crack propagates from the outer surface of the sample to the center along the radius and simultaneously propagates along the circumferential direction;
2) Selecting the maximum area on a fracture on a step crack plane to measure the step crack parameters;
3) The step crack parameters comprise a plane length a and a radial width b, a and b are on the same step crack plane, and the measuring directions are mutually vertical;
4) The plane shape of the step crack is elliptical, the hydrogen sulfide stress corrosion resistance sensitivity is related to the maximum step crack plane area S, the sensitivity index R = K pi a b, K is a constant, and the value range is 1-2.
Further, the slow tensile loading test is loaded along the length direction of the sample, and the tensile direction is parallel to the length direction of the sample.
Further, the stretching direction of the slow tensile loading test is vertical to the plane of the step crack, and the stretching direction is vertical to the crack propagation direction and has a difference of 90 degrees.
Furthermore, the test solution is a Nace standard A solution, and the concentration of hydrogen sulfide is 0-3500 ppm.
Compared with the prior art, the invention has the beneficial effects that:
the invention tests the stress corrosion resistance of the oil well pipe material in a service environment or a simulated actual environment, evaluates the stress corrosion resistance sensitivity of the oil well pipe material through fracture morphology observation and step crack parameters, further evaluates the practicability of the oil well pipe material in a specific working condition environment, and guides material selection and equipment maintenance.
Drawings
FIG. 1 is a macroscopic fracture morphology diagram of a fracture sample when the concentration of hydrogen sulfide is zero;
FIG. 2 is a side profile plot of a fracture sample when the hydrogen sulfide concentration is zero;
FIG. 3 is a macroscopic fracture morphology diagram of a fracture sample at a hydrogen sulfide concentration of 1000 ppm;
FIG. 4 is a profile plot of a fracture sample at a hydrogen sulfide concentration of 1000 ppm;
FIG. 5 is a macroscopic fracture morphology diagram of a fracture sample when the concentration of hydrogen sulfide is 3500 ppm;
FIG. 6 is a profile plot of a fracture sample at a hydrogen sulfide concentration of 3500 ppm;
fig. 7 is a view showing a method for measuring the plane length a and the radial width b of the step crack.
Detailed Description
The following detailed description of the present invention will be made with reference to the accompanying drawings.
A method for testing the hydrogen sulfide stress corrosion resistance sensitivity of an oil well pipe based on a fracture sample comprises the following steps:
step 1: processing a sample into a set size, and pretreating the surface of the sample;
and 2, step: mounting the sample on a stretching device in a reaction kettle, adding a proper amount of test solution into the reaction kettle, and sealing the reaction kettle; the test solution is Nace standard A solution, and the concentration of hydrogen sulfide is 0-3500 ppm.
And step 3: adjusting the concentration of hydrogen sulfide in the test solution, and quickly stretching and preloading the hydrogen sulfide to 70-80% yield strength value of the test sample; the strain rate of the rapid stretching is more than or equal to 1 multiplied by 10 -4 mm/s。
And 4, step 4: after the preloading is stable, starting to perform a slow tensile loading test at a set strain rate until the test sample is broken, and recording a test result; the strain rate of the slow tensile loading test is 1 multiplied by 10 -7 ～5×10 -5 mm/s。
And 5: and finally, taking out the fractured tensile sample, removing corrosion products on the surface of the sample and on the fracture, and evaluating the stress corrosion resistance of the oil well pipe material through fracture morphology observation and step crack parameters. The method specifically comprises the following steps:
1) The crack propagation direction is along the step crack plane, and the crack propagates from the outer surface of the sample to the center along the radius and simultaneously propagates along the circumferential direction;
2) Selecting the maximum area on the fracture on the step crack plane to measure the step crack parameters;
3) As shown in fig. 7, the step crack parameters include a plane length a and a radial width b, where a and b are on the same step crack plane, and the measurement directions are perpendicular to each other;
4) The plane shape of the step crack is elliptical, the hydrogen sulfide stress corrosion resistance sensitivity is related to the maximum step crack plane area S, the sensitivity index R = K pi a b, K is a constant, and the value range is 1-2.
The fracture appearance is observed by a microscope, the magnification is 10-100, when the step crack is small, the magnification is large, when the step crack is large, the magnification is small, the sample fracture appearance is ensured to be complete, and the step crack parameter measurement is accurate.
The microscope comprises an electron microscope or a laser confocal microscope, fractures of a sample are uneven, step cracks are formed in the circumferential direction of the sample, and the sample needs to have strong focusing capacity.
The slow tensile loading test is loaded along the length direction of the sample, and the tensile direction is parallel to the length direction of the sample. The stretching direction of the slow stretching loading test is vertical to the plane of the step crack, and the stretching direction is vertical to the crack propagation direction, and the difference is 90 degrees.
Example 1
The test material is a sulfur-resistant oil well pipe 110S, the yield strength is 800Mpa, and the method consists of sample I processing, surface treatment II, slow tensile loading test III, fracture morphology observation IV and step crack parameter measurement.
The sample processing in the step I is to process the test material into a cylindrical tensile sample with the length of 72mm, the diameter of 6.40mm and the surface smoothness of 0.3 mu m;
the surface treatment in the step II is to clean the sample in the step I by ultrasonic waves, and the sample is respectively cleaned in acetone and absolute ethyl alcohol once for removing residues and grease on the surface of the sample;
the slow tensile loading test in the step III is to adopt a slow strain rate tensile testing machine, the test temperature is room temperature, a Nace standard A solution is injected into a reaction kettle, the reaction kettle is closed, high-purity nitrogen is introduced to remove oxygen for 2 hours, the concentration of hydrogen sulfide in the solution is 0, a sample is loaded to 600Mpa in advance, the sample is kept in an elastic stress deformation stage, and then the elastic stress deformation stage is carried out according to the ratio of 5 x 10 -6 The slow tensile loading test is started at the strain rate of mm/s, after the test is finished, the test result is recorded, the fractured tensile sample is taken out, corrosion products on the surface of the sample and the fracture are removed, the surface of the sample is ensured to present metallic luster, and the fracture appearance is clear;
in the step IV, fracture morphology observation and step crack parameter measurement are performed by vertically placing a fractured tensile sample on an objective table by using a scanning electron microscope, wherein the tensile direction is vertical to the plane of the objective table, the working distance between a fracture and a lens is adjusted to be 12.9mm, the magnification is 58 times, the fracture morphology is shot after focusing is clear, the fracture is in a cup cone shape as shown in a figure 1-2, the fracture belongs to ductile fracture and does not generate stress corrosion, step crack parameters a and b are recorded as 0, a stress corrosion sensitivity formula R = K pi a x b is introduced, K takes a value of 2, and test results are shown in a table 1.
Example 2
The test material is a sulfur-resistant oil well pipe 110S, the yield strength is 800Mpa, and the method comprises the steps of sample I processing, II surface treatment, III slow tensile loading test, IV fracture morphology observation and step crack parameter measurement.
The sample processing in the step I is to process the test material into a cylindrical tensile sample with the length of 72mm, the diameter of 6.40mm and the surface smoothness of 0.3 mu m;
the surface treatment in the step II is to wash the sample in the step I by ultrasonic waves, and the sample is washed in acetone and absolute ethyl alcohol respectively for one time so as to remove residues and grease on the surface of the sample;
the slow tensile loading test in the step III is to adopt a slow strain rate tensile testing machine, the test temperature is room temperature, a Nace standard A solution is injected into a reaction kettle, high-purity nitrogen is used for removing oxygen for 2 hours, and then the high-purity nitrogen is addedProper amount of analytically pure sodium sulfide, ensuring the hydrogen sulfide concentration in the solution to be 1000ppm after full reaction, sealing the reaction kettle, loading a sample to 600Mpa in advance, keeping the sample in an elastic stress deformation stage, and then carrying out the following steps of 5 × 10 -6 The slow tensile loading test is started at the strain rate of mm/s, after the test is finished, the test result is recorded, the fractured tensile sample is taken out, corrosion products on the surface of the sample and the fracture are removed, the surface of the sample is ensured to present metallic luster, and the fracture appearance is clear;
in the step IV, fracture morphology observation and step crack parameter measurement are performed by vertically placing a fractured tensile sample on an objective table by using a scanning electron microscope, wherein the tensile direction is vertical to the plane of the objective table, the working distance between a fracture and a lens is adjusted to be 12.7mm, the magnification is 41 times, the fracture morphology is shot after focusing is clear, the step crack plane with the largest area is selected as shown in a figure 3-4, the length a and the radial width b of the plane are calculated by software, the a and the b are positioned on the same step crack plane, the measurement directions are vertical to each other, a stress corrosion sensitivity formula R = K pi a b is introduced, the K value is 2, and the test result is shown in a table 1.
Example 3
The test material is a sulfur-resistant oil well pipe 110S, the yield strength is 800Mpa, and the method consists of sample I processing, surface treatment II, slow tensile loading test III, fracture morphology observation IV and step crack parameter measurement.
The sample processing in the step I is to process the test material into a cylindrical tensile sample with the length of 72mm, the diameter of 6.40mm and the surface finish of 0.3 mu m;
the surface treatment in the step II is to wash the sample in the step I by ultrasonic waves, and the sample is washed in acetone and absolute ethyl alcohol respectively for one time so as to remove residues and grease on the surface of the sample;
the slow tensile loading test in the step III adopts a slow strain rate tensile testing machine, the testing temperature is room temperature, a Nace standard A solution is injected into a reaction kettle, the reaction kettle is closed, high-purity nitrogen is firstly introduced to remove oxygen for 2 hours, then high-purity hydrogen sulfide gas is introduced until the solution is saturated, the concentration of hydrogen sulfide in the solution under normal pressure is 3500ppm in advanceThe test specimen is loaded to 600MPa, the test specimen is kept in the elastic stress deformation stage, and then the elastic stress deformation stage is carried out according to 5X 10 -6 The slow tensile loading test is started at the strain rate of mm/s, after the test is finished, the test result is recorded, the fractured tensile sample is taken out, corrosion products on the surface of the sample and the fracture are removed, the surface of the sample is ensured to present metallic luster, and the fracture appearance is clear;
in the step IV, fracture appearance observation and step crack parameter measurement are performed by vertically placing a fractured tensile sample on an objective table by using a scanning electron microscope, wherein the tensile direction is vertical to the plane of the objective table, the working distance between a fracture and a lens is adjusted to be 11.7mm, the magnification is 40 times, the fracture appearance is shot after focusing is clear, as shown in figures 5-6, a step crack plane with the largest area is selected, the plane length a and the radial width b are calculated by software, a and b are positioned on the same step crack plane, the measurement directions are mutually vertical, a stress corrosion sensitivity formula R = K pi a b is introduced, K takes a value of 2, and the test result is shown in a table 1.
TABLE 1 Slow tensile test results for oil well pipes at different hydrogen sulfide concentrations
From the above test results, it can be seen that: in a Nace standard A solution, when the concentration of hydrogen sulfide is zero, the oil well pipe material is not subjected to stress corrosion, a fracture is in a cup cone shape and belongs to ductile fracture, the sensitivity index of the stress corrosion is 0, the sensitivity index of the stress corrosion of the oil well pipe material is increased from 59.52 to 88.86 with the increase of the concentration of the hydrogen sulfide, the fracture appearance presents step cracks, and the oil well pipe material has obvious stress corrosion characteristics, which are consistent with the calculation results of conventional stress corrosion sensitivity, such as an elongation loss ratio and a fracture time loss ratio. The method realizes the measurement of the stress corrosion resistance sensitivity of the oil well pipe, and more accurately and comprehensively evaluates the stress corrosion resistance of the oil well pipe material through fracture morphology observation and step crack parameter calculation.
Example 4
The samples used in the test were oil country tubular goods A and B, which were two different types of oil country tubular goods (for example, oil country tubular goods different in material and different in rolling, heat treatment, and the like, and the same explanation is given here in the following examples). The method comprises the steps of sample I processing, surface treatment II, slow tensile loading test III, fracture morphology observation IV and step crack parameter measurement.
The sample processing in the step I is to process the test material into a cylindrical tensile sample with the length of 72mm, the diameter of 6.40mm and the surface finish of 0.3 mu m;
the surface treatment in the step II is to wash the sample in the step I by ultrasonic waves, and the sample is washed in acetone and absolute ethyl alcohol respectively for one time so as to remove residues and grease on the surface of the sample;
the slow tensile loading test in the step III is to adopt a slow strain rate tensile testing machine, the test temperature is room temperature, a Nace standard A solution is injected into a reaction kettle, the reaction kettle is closed, high-purity nitrogen is firstly introduced to remove oxygen for 2 hours, then high-purity hydrogen sulfide gas is introduced until the solution is saturated, the concentration of hydrogen sulfide in the solution is 3500ppm at normal pressure, and after the preloading is stable, the slow tensile loading test is started according to 1 x 10 -7 The method comprises the following steps of (1) starting a slow tensile loading test at a strain rate of mm/s, recording a test result after the test is finished, taking out a fractured tensile sample, removing corrosion products on the surface and fracture of the sample, and ensuring that the surface of the sample presents metallic luster and the fracture appearance is clear;
in the step IV, fracture morphology observation and step crack parameter measurement are performed by vertically placing a fractured tensile sample on an objective table by adopting a scanning electron microscope, wherein the tensile direction is vertical to the plane of the objective table, the working distance between a fracture and a lens is adjusted to be 10mm, the magnification is 30 times, the fracture morphology is shot after clear focusing, the step crack plane with the largest area is selected, the plane length a and the radial width b are calculated by software, a and b are positioned on the same step crack plane, the measurement directions are mutually vertical, a stress corrosion sensitivity formula R = K pi a b is introduced, and K takes 2, the test result is shown in a table 2, and analysis shows that: the sensitivity indexes of the stress corrosion are in the order from high to low; b is more than A, and the hydrogen sulfide stress corrosion resistance performance is in the order from high to low: a > B.
Table 2 slow tensile test results of oil well pipes
Example 5
The samples used in the test were two types of oil country tubular goods A and B, which were two different types of oil country tubular goods (for example, oil country tubular goods different in material and different in rolling, heat treatment, and the like, and the same explanation is given here in the following examples). The method comprises the steps of sample I processing, surface treatment II, slow tensile loading test III, fracture morphology observation IV and step crack parameter measurement.
The sample processing in the step I is to process the test material into a cylindrical tensile sample with the length of 72mm, the diameter of 6.40mm and the surface finish of 0.3 mu m;
the surface treatment in the step II is to wash the sample in the step I by ultrasonic waves, and the sample is washed in acetone and absolute ethyl alcohol respectively for one time so as to remove residues and grease on the surface of the sample;
the slow tensile loading test in the step III is to adopt a slow strain rate tensile testing machine, the test temperature is room temperature, a Nace standard A solution is injected into a reaction kettle, high-purity nitrogen is used for removing oxygen for 2 hours, a proper amount of analytically pure sodium sulfide is added, the concentration of hydrogen sulfide in the solution is ensured to be 1000ppm after full reaction, the reaction kettle is closed, and after the preloading is stable, the method begins to adopt a 5 x 10 mode -5 The slow tensile loading test is started at the strain rate of mm/s, after the test is finished, the test result is recorded, the fractured tensile sample is taken out, corrosion products on the surface of the sample and the fracture are removed, the surface of the sample is ensured to present metallic luster, and the fracture appearance is clear;
in the step IV, fracture appearance observation and step crack parameter measurement adopt a scanning electron microscope, a fractured tensile sample is vertically placed on an objective table, the tensile direction is vertical to the plane of the objective table, the working distance between a fracture and a lens is adjusted to be 20mm, the magnification is 100 times, the fracture appearance is shot after clear focusing, the step crack plane with the largest area is selected, the plane length a and the radial width b are calculated through software, a and b are positioned on the same step crack plane, the measurement directions are mutually vertical, a stress corrosion sensitivity formula R = K pi a b is introduced, K takes a value of 2, the test result is shown in a table 3, and analysis shows that: the susceptibility index of the stress corrosion is in the order from high to low; b is more than A, and the hydrogen sulfide stress corrosion resistance performance is in the order from high to low: a > B.
Table 3 slow tensile test results of oil well pipes
The above embodiments are implemented on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are given, but the scope of the present invention is not limited to the above embodiments. The methods used in the above examples are conventional methods unless otherwise specified.
Claims (7)
1. A method for testing the hydrogen sulfide stress corrosion resistance sensitivity of an oil well pipe based on a fracture sample is characterized by comprising the following steps:
step 1: processing a sample into a set size, and pretreating the surface of the sample;
and 2, step: mounting the sample on a stretching device in a reaction kettle, adding a proper amount of test solution into the reaction kettle, and sealing the reaction kettle;
and step 3: adjusting the concentration of hydrogen sulfide in the test solution, and quickly stretching and preloading the hydrogen sulfide to 70-80% yield strength value of the test sample;
and 4, step 4: after the preloading is stable, starting to perform a slow tensile loading test at a set strain rate until the test sample is broken, and recording a test result;
and 5: and finally, taking out the fractured tensile sample, removing corrosion products on the surface of the sample and the fracture, and evaluating the stress corrosion resistance of the oil well pipe material through fracture morphology observation and step crack parameters.
2. The method of claim 1The method for testing the hydrogen sulfide stress corrosion resistance sensitivity of the oil well pipe based on the fracture sample is characterized in that the strain rate of the slow tensile loading test is 1 multiplied by 10 -7 ～5×10 -5 mm/s。
3. The method for testing the hydrogen sulfide stress corrosion resistance sensitivity of the oil well pipe based on the fracture sample as claimed in claim 1, wherein the strain rate of the rapid stretching is 1 x 10 or more -4 mm/s。
4. The method for testing the stress corrosion resistance sensitivity of the oil well pipe based on the fractured sample according to claim 1, wherein the evaluating of the stress corrosion resistance performance of the oil well pipe material in the step 5 specifically comprises the following steps:
1) The crack propagation direction is along the step crack plane, and the crack simultaneously propagates from the outer surface of the sample along the radial direction and the circumferential direction;
2) Selecting the maximum area on a fracture on the step crack plane to measure the step crack parameters;
3) The step crack parameters comprise a plane length a and a radial width b, wherein a and b are on the same step crack plane, and the measuring directions are mutually vertical;
4) The plane shape of the step crack is elliptical, the hydrogen sulfide stress corrosion resistance sensitivity is related to the maximum step crack plane area S, the sensitivity index R = K pi a b, K is a constant, and the value range is 1-2.
5. The method for testing the hydrogen sulfide stress corrosion resistance sensitivity of the oil well pipe based on the fracture sample as claimed in claim 1, wherein the slow tensile loading test is loaded along the length direction of the sample, and the tensile direction is parallel to the length direction of the sample.
6. The method for testing the hydrogen sulfide stress corrosion resistance sensitivity of the oil well pipe based on the fracture specimen is characterized in that the stretching direction of the slow tensile loading test is perpendicular to the plane of the step crack, and the stretching direction is perpendicular to the crack propagation direction and has a 90-degree difference.
7. The method for testing the hydrogen sulfide stress corrosion resistance sensitivity of the oil well pipe based on the fractured sample according to claim 1, wherein the test solution is a Nace standard A solution, and the concentration of hydrogen sulfide is 0-3500 ppm.
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| CN115931567A (en) * | 2023-01-03 | 2023-04-07 | 华东理工大学 | Stress corrosion sensitivity evaluation method and system for welding component |
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| CN115931567A (en) * | 2023-01-03 | 2023-04-07 | 华东理工大学 | Stress corrosion sensitivity evaluation method and system for welding component |
| CN115931567B (en) * | 2023-01-03 | 2023-10-27 | 华东理工大学 | Stress corrosion sensitivity assessment method and system for welded component |
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