CN109520856B - Small sample creep crack propagation test method - Google Patents
Small sample creep crack propagation test method Download PDFInfo
- Publication number
- CN109520856B CN109520856B CN201811493998.8A CN201811493998A CN109520856B CN 109520856 B CN109520856 B CN 109520856B CN 201811493998 A CN201811493998 A CN 201811493998A CN 109520856 B CN109520856 B CN 109520856B
- Authority
- CN
- China
- Prior art keywords
- small sample
- creep
- sample
- small
- crack growth
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/18—Performing tests at high or low temperatures
Abstract
The invention provides a small sample creep crack growth test method which has the advantages of small volume of required materials, little damage of test materials to equipment and capability of obtaining creep crack growth data similar to that of a standard sample. The test method comprises the following steps: taking and preparing small samples for creep crack growth tests from the equipment or the samples; prefabricating an initial crack on a small sample by using a fatigue testing machine; welding a lead wire for current input and voltage measurement on the surface of the small sample; mounting the small sample on a creep crack growth test device, heating the small sample, and applying a load after sufficient heat preservation; collecting the load line displacement of a small sample by using a displacement extensometer; obtaining the crack length of the small sample by a direct current or alternating current potential method according to the measured voltage; and processing the test data to obtain creep crack initiation time and creep crack propagation rate. The test method is suitable for the conditions that sampling is difficult to perform on in-service components, thin-wall parts, welding seams, equipment using functional gradient materials and the like.
Description
Technical Field
The invention belongs to the technical field of material performance measurement, and particularly relates to a creep crack growth test method suitable for a small sample.
Background
A compact tensile specimen 62.5mm long, 60mm wide and 25mm thick is generally required for creep crack growth tests, and the blank volume required for the tests is large. The material selection on some active equipment can affect the service life of the equipment and even cause the damage of the equipment. In some thin-wall equipment such as heat exchange tubes, engine blades and the like, welding seams and equipment using functionally graded materials are formed, and the standard samples cannot be manufactured due to small material thickness. Under these circumstances, a small sample test method is urgently needed in order to obtain creep crack growth performance of the material.
Previous research results show that the shape and size of the sample affect the restraint state of the creep crack tip (i.e., crack tip restraint), and further affect the creep crack propagation rate.
The higher the level of crack tip restraint, the faster the creep crack growth rate achieved by the test specimen. When the restraint level reaches a certain degree, the creep crack propagation rate tends to be stable. The deep crack compact tensile specimen specified in the standard for creep crack growth rate test methods for metallic materials (HB7623-1998) is a higher level of restraint and more conservative test data can be obtained with the standard specimen.
Generally, the crack tip restraint level of a small sample is lower, the crack propagation rate obtained by using the small sample is slower than that of a standard sample, and the creep crack propagation rate between a large sample and a small sample can be accurately correlated by some technical treatment, but the existing method is not mature.
Therefore, there is a need for a small sample creep crack growth test method that can obtain creep crack growth data similar to that of a standard sample.
Disclosure of Invention
The invention is completed for solving the problems in the prior art, and aims to provide a small sample creep crack growth test method which has the advantages of small volume of required materials, less damage of test materials to equipment and capability of obtaining creep crack growth data similar to that of a standard sample.
In order to achieve the above object, the inventors have intensively studied and provided the following means.
The small sample creep crack growth test method comprises the following steps:
s1: taking and preparing small samples for creep crack growth tests from the equipment or the samples;
s2: prefabricating an initial crack on the small sample by using a fatigue testing machine;
s3: welding a lead for current input and voltage measurement on the surface of the small sample;
s4: mounting the small sample on a creep crack growth test device, heating the small sample, and applying a load after sufficient heat preservation;
s5: collecting the load line displacement of the small sample by using a displacement extensometer;
s6: obtaining the crack length of the small sample by a direct current or alternating current potential method according to the measured voltage;
s7: and processing the test data to obtain creep crack initiation time and creep crack propagation rate.
In the creep crack growth test method for a small sample, the small sample is preferably a round compact tensile small sample having a diameter of 20mm, a thickness B of 1 to 5mm, and an initial crack length a0The ratio of the width W of the sample to the width W of the sample is 0.3-0.8.
In the small sample creep crack growth test method, the small sample is preferably a compact tensile small sample having a width W of 12.5mm, a thickness B of 1 to 5mm, and a length a of an initial crack0The ratio of the width W of the sample to the width W of the sample is 0.3-0.8.
In step S1 of the creep crack growth test method for small samples, the prepared small samples are preferably subjected to surface grinding, surface polishing and/or electropolishing to remove the surface residual stress of the small samples.
In step S2 of the small sample creep crack growth test method, the maximum load at the time of pre-cracking is preferably lower than the load applied to the small sample at the time of testing.
In step S4 of the small sample creep crack growth test method, the creep crack growth test apparatus is preferably a test apparatus for measuring creep crack growth of the small sample, the small sample is attached to a sample-loading plate by a jig, one end of the small sample is fixed to the sample-loading plate, and the other end of the small sample is connected to a sample-loading lever.
In step S7 of the small sample creep crack growth test method, it is preferable that the time corresponding to the creep crack initiation time of 0.2mm of crack growth be the creep crack initiation time; the creep crack growth rate described above is expressed in da/dt and is derived from time t by plotting crack length a against time t using origin software.
In step S6 of the small specimen creep crack growth test method, the crack length of the round compact elongated small specimen is preferably calculated using the following formula (1),
where a is the crack length after propagation, W is the specimen width, V0Is the initial voltage and V is the measured voltage.
In step S7 of the small sample creep crack growth test method, the creep crack growth rate is preferably characterized by a parameter C calculated by the following formula (2):
where P is the applied load, B is the thickness of the specimen, a is the crack length after propagation, and W is the specimen width; n is a power law creep index and is obtained by testing and fitting the relation between the steady-state creep strain rate and the stress under the log-log coordinate through a creep experiment;
is a creep load linear displacement rate, and is calculated by the following formula (3),
wherein P, B and a are as defined above;
is the linear displacement rate of the load, and is formed by the relation curve of the linear displacement of the load and the timeObtaining the time derivative; e ═ E/(1-v)2) E is the modulus of elasticity and v is the Poisson's ratio; m is the power law hardening equation εp＝α(σ/σys)mIn (1), alpha is the coefficient of the power-law hardening equation, ∈pIs plastic strain, σ is stress, σysObtaining alpha and m values by fitting the relation between the plastic strain and the stress of the material for yield strength; j. the design is a squarepIs a plastic component, and is calculated by the following formula (4),
wherein P, B, a, W, alpha, m and sigmaysIs as defined above, h of small sample1(a/W,m)Obtained by finite element software calculation.
Effects of the invention
According to the small sample creep crack growth test method, creep crack growth data similar to that of a standard sample can be obtained, the volume of required materials is greatly reduced, and the damage of test materials to equipment is reduced.
In addition, the test method is suitable for testing by using the test device which can simultaneously complete creep and creep crack growth tests of various types of small samples in a vacuum environment, can prevent oxidation, performs the test at high flux and obtains more stable creep crack growth test data.
Other advantageous effects of the present invention are explained in the following further disclosure.
Drawings
FIG. 1 is a schematic view of an example of a round compact tensile small sample used in the small sample creep crack growth test method of the present invention.
FIG. 2 is a schematic view of an example of a compact tensile small sample used in the small sample creep crack growth test method of the present invention.
FIG. 3 is a schematic diagram of a crack length measurement method in the small specimen creep crack growth test method of the present invention.
Figure 4 shows a schematic comparison of a standard compact tensile specimen with a round compact tensile small specimen.
Fig. 5 is a graph showing the change in linear displacement of load with time of a round compact tensile small sample in the test example of the present invention.
FIG. 6 is a graph showing the voltage change with time of a round compact tensile small sample in the test example of the present invention.
FIG. 7 is a graph showing the change of crack length with time of a round compact tensile small sample in the test example of the present invention.
FIG. 8 is a graph of creep crack rate da/dt versus C for round compact tensile coupons in test examples of the present invention.
FIG. 9 is a comparison of crack propagation rates obtained from the round compact tensile coupon test in the test examples of the present invention with the results of the standard compact tensile coupon test.
Description of the symbols
1 Power supply
2 Voltage acquisition instrument
3 conducting wire
4 Small sample
Detailed Description
The technical features of the present invention will be described below with reference to preferred embodiments and drawings, which are intended to illustrate the present invention and not to limit the present invention. The drawings are greatly simplified for illustration purposes and are not necessarily drawn to scale.
It is to be understood that the preferred embodiments of the present invention are shown in the drawings only, and are not to be considered limiting of the scope of the invention. Various obvious modifications, variations and equivalents may be made to the present invention by those skilled in the art on the basis of the examples shown in the drawings, and the technical features in the different embodiments described below may be arbitrarily combined without contradiction, and these are within the scope of protection of the present invention.
[ Small sample for creep crack growth test ]
The present invention is a method for performing a creep crack growth test using a small sample, and the small sample used in the present invention is described below with reference to fig. 1 and 2.
The small sample used in the present invention may be a round compact tensile small sample or a compact tensile small sample, and a round compact tensile small sample is preferable.
In preparing small specimens, specimens are taken from equipment or specimens and prepared into a prescribed size and shape as needed, and initial cracks are usually prepared on the small specimens using a fatigue tester.
As shown in FIG. 1, a round compact tensile small sample has a diameter of 20mm, a thickness B of 1 to 5mm, and an initial crack length a0The ratio of the width W of the sample to the width W of the sample is 0.3-0.8. Among them, the thickness is more preferably 1 to 3mm, still more preferably 1 to 2mm, and particularly preferably 1 mm. Length of initial crack a0The ratio of the width W to the width W of the sample is more preferably 0.3 to 0.8, still more preferably 0.3 to 0.6, and particularly preferably 0.4 to 0.5.
As shown in FIG. 2, the compact tensile test piece had a width W of 12.5mm, a thickness B of 1 to 5mm, and a length a of an initial crack0The ratio of the width W of the sample to the width W of the sample is 0.3-0.8. Among them, the thickness is more preferably 1 to 3mm, still more preferably 1 to 2mm, and particularly preferably 1 mm. Length of initial crack a0The ratio of the width W to the width W of the sample is more preferably 0.3 to 0.8, still more preferably 0.3 to 0.6, and particularly preferably 0.4 to 0.5.
The round compact tensile small sample and the compact tensile small sample are provided with two loading holes, and the centers of the two holes are connected with each other (O)1And O2The connecting line) is a loading line, and a plane containing the loading line and orthogonal to the side face is taken as a reference plane. The sample width W is the distance from the reference plane to the back surface of the sample.
[ creep crack growth test method for Small sample ]
The small sample creep crack growth test method of the present invention includes the following steps S1 to S6.
Step S1:
small specimens for creep crack growth tests were taken and prepared from the equipment or specimens. The small specimens used in the present invention were prepared as described in [ creep crack growth test small specimen ]. The small size of the small sample used greatly reduces the consumption of test materials.
In a preferred embodiment, the prepared small sample is subjected to surface grinding, surface polishing and/or electropolishing to remove the surface residual stress of the small sample.
Step S2:
an initial crack was prepared on the above small sample using a fatigue tester. Initial cracks were prepared on the coupons as described in [ creep crack propagation test coupons ] above.
When an initial crack is preformed on a small sample by using a fatigue testing machine, the maximum load when the crack is preformed is not larger than the load applied to the small sample in the test, and the stress ratio is 0.1. Furthermore, the prepared fatigue crack length of small specimens is usually not less than 1 mm.
Step S3:
before proceeding to step S3, the sample may be washed with an ultrasonic washer and dried.
In step S3, wires for current input and voltage measurement are welded on the surface of the small sample. As shown in fig. 3, the current input leads are connected at the farthest ends from the crack surface, respectively; the wires for voltage measurement are respectively connected to the side surfaces close to the wire cutting gaps.
Step S4:
next, the small sample is mounted on a creep crack growth test apparatus for measuring creep crack growth of the small sample, the small sample is mounted on a sample loading plate by a jig, one end of the small sample is fixed to the sample loading plate through a loading hole, and the other end is connected to a sample loading lever. Then the small sample is heated and fully insulated, and then a load is applied.
In a preferred embodiment, the creep crack growth test apparatus is a high-throughput creep and creep crack growth test apparatus for small samples, which can provide a vacuum environment, reduce the influence of oxidation on the measurement result, and improve the measurement accuracy, and which can simultaneously perform creep and creep crack growth tests for a plurality of small samples to perform a high-throughput test.
When the small sample is heated, a mica sheet can be adopted to be padded between the thermocouple and the sample so as to avoid the voltage on the sample from influencing the temperature measurement and control.
Two lead wires for current input welded on the small sample are connected with a direct current power supply or an alternating current power supply, and two lead wires for voltage measurement welded on the small sample are connected with a voltage acquisition instrument. When the crack length is measured by a direct current potential method, the input current is 1-3A, and 1A is particularly preferred.
The target temperature of the heating furnace is set, and heating is started. And after the target temperature is reached, carrying out heat preservation for at least 0.5h, and then starting a loading test.
Step S5:
and collecting the load line displacement of the small sample by using a displacement extensometer. The displacement extensometer is fixed on the sample clamp, and the clamp is connected with the small sample by adopting a pin. And (4) with the continuous expansion of the crack, the distance between the upper clamp and the lower clamp is continuously increased, and the displacement is determined as the displacement of the crack load line.
Step S6:
and obtaining the crack length of the small sample by a direct current or alternating current potential method according to the voltage measured by the voltage acquisition instrument.
In a preferred embodiment, in the case of using a round compact tensile small sample, the crack length of the round small sample can be calculated by the following formula (1),
where a is the crack length after propagation, W is the specimen width, V0Is the initial voltage and V is the measured voltage.
The above equation (1) is applicable to the case where the half distance between the voltage leads is measured to be 1.5 mm.
Step S7:
and processing the test data to obtain creep crack initiation time and creep crack propagation rate.
In a preferred embodiment, the creep crack initiation time is defined as the time corresponding to 0.2mm of crack propagation. The creep crack growth rate described above is expressed in da/dt and is derived from time t by plotting crack length a against time t using origin software.
In a preferred embodiment, the above-mentioned creep crack growth rate da/dt is characterized by a parameter C. The parameter C is suitable for cracks that propagate in a brittle or ductile mode, and is used for data correlation, characterized by the fact that the creep crack propagation data under different loads will tend to be identical in log-log coordinates. The above parameter C is calculated by the following formula (2):
where P is the applied load, B is the thickness of the specimen, a is the crack length after propagation, and W is the specimen width; n is a power law creep index and is obtained by testing and fitting the relation between the steady-state creep strain rate and the stress under the log-log coordinate through a creep experiment;
is a creep load linear displacement rate, and is calculated by the following formula (3),
wherein P, B and a are as defined above;
the linear load displacement rate is obtained by time derivation according to a relation curve of the linear load displacement and time; e ═ E/(1-v)2) E is the modulus of elasticity and v is the Poisson's ratio; m is the power law hardening equation εp＝α(σ/σys)mIn (1), alpha is the coefficient of the power-law hardening equation, ∈pIs plastic strain, σ is stress, σysObtaining alpha and m values by fitting the relation between the plastic strain and the stress of the material for yield strength; j. the design is a squarepIs a plastic component, and is calculated by the following formula (4),
wherein P, B, a, W, alpha, m and sigmaysIs as defined above, h of small sample1(a/W,m)Obtained by finite element software calculation.
According to the small sample creep crack growth test method, the small sample is used for creep crack growth test, creep crack growth data similar to that of a standard sample can be obtained, the volume of the required material is greatly reduced, and the damage of the test material to equipment is reduced.
In addition, the test method is suitable for testing by using the test device which can simultaneously complete creep and creep crack growth tests of various types of small samples in a vacuum environment, can prevent oxidation, performs the test at high flux and obtains more stable creep crack growth test data.
Test examples
In order to further explain the small sample creep crack growth test method and its effects of the present invention, the technical means of the present invention will be explained by the following test examples.
As a material tested in the test examples of the present invention, Inconel625 nickel-based alloy for aircraft engine regenerator manufacturing (supplied by hualong special steel ltd, yang, jiang su) was used, and the thickness of the steel plate was 20 mm. Prior to testing, the material was solution treated at 1050 ℃ for 4 hours and then cooled to room temperature. The basic mechanical properties of the Inconel625 nickel-base alloy at 650 ℃ are shown in Table 1.
[ Table 1]
A circular blank having a diameter of 20mm and a thickness of 1.6mm was cut out of the steel sheet by electric discharge machining. Adopt linear cutting and drilling machine processing initial breach and loading hole, through processing such as surface abrasive paper is polished, electrolysis, process thickness B to 1mm, sample width W is 15mm in addition, and loading hole diameter is 3.75 mm.
Then, the processed sample was subjected to initial fatigue crack preparation. In the test in this test example, the applied load was 420N, so that the maximum load of the prepared fatigue crack was 420N, the stress ratio was 0.1, and the prepared fatigue crack length was 1mm, thereby obtaining a round compact tensile small sample (# 1) shown in FIG. 4.
Next, the small sample was cleaned using an ultrasonic cleaning machine. Platinum wire leads for current input and voltage measurement were spot welded to the surface of the small sample. The current input wires are respectively connected with the farthest ends away from the crack surface; the wires for voltage measurement are respectively connected to the side surfaces close to the linear cutting gap, and the half distance between the voltage measurement lead wires is 1.5 mm.
A high-flux small sample creep and creep crack growth test device is adopted, one end of a small sample is fixed on a sample loading disc through a loading hole, and the other end of the small sample is connected with a loading rod. The test device provides a vacuum environment, can prevent a small sample from being oxidized at high temperature, and adopts the mica sheet to be padded between the thermocouple and the sample so as to avoid the influence of voltage on the sample on temperature measurement and control. And four wires are respectively connected with a direct current source and a voltage collector. The target temperature of the furnace was set at 650 ℃ and heating was started. And after the target temperature is reached, the temperature is kept for 0.5h, and then the loading test is started, wherein the load is 420N.
And acquiring the crack load line displacement of the small sample by using a displacement extensometer. In the test process, the displacement extensometer automatically collects and records load linear displacement data and records the data in real time. The load line displacement versus time for the round compact tensile coupon is shown in figure 5.
In the test process, the crack length is measured by adopting a direct current potential method, and the input current is 1A. And automatically acquiring and recording voltage data in the whole process. The voltage versus time for the round compact tensile small coupon is shown in figure 6. By using the function relation between the crack length and the voltage and combining the voltage data in fig. 6, the change curve of the crack length of the round compact tensile small sample along with the time is calculated and obtained, as shown in fig. 7.
The obtained test data are then processed. From fig. 7, the time corresponding to the crack growth amount of 0.2mm, i.e., the creep crack initiation time was found, and the creep crack initiation time in this test example was 330 hours. The creep crack growth rate da/dt is obtained by deriving the time t from the crack length versus time curve in FIG. 7. The creep crack growth rate da/dt is related by C, the calculation equation of C is shown in the invention content step S7, and the linear displacement rate of the load in the calculation process
Derived from the load line displacement versus time curve in fig. 5. The creep crack growth rate da/dt is plotted against C in fig. 8. It can be seen that the creep crack growth rate da/dt is linear with C on a log-log scale. Using the power law equation da/dt ═ D0C*φThe creep crack growth rate of the Inconel625 nickel-base alloy at 650 ℃ was determined by fitting the curves of fig. 8. Further, the creep crack growth rate at any C x was calculated.
Creep crack growth tests were conducted in parallel on three sets of round compact tensile small specimens (1#, 2#, 3#) according to the method described above in the test examples, and the creep crack growth rates da/dt and C obtained by data processing are shown in fig. 9.
In addition, a creep crack growth test was conducted using a standard compact tensile specimen having a length of 62.5mm, a width of 60mm and a thickness of 25mm, and as shown in FIG. 4, W was 50mm and a025mm and the diameter of the loading hole is 12.5 mm. Creep crack growth tests were performed in parallel on standard compact tensile specimens (1#, 2#, 3#), and the creep crack growth rates da/dt versus C were obtained according to ASTM E1457, and are shown in fig. 9.
As can be seen from fig. 9, the creep crack growth rate data obtained by the creep crack growth test method using the round compact tensile small sample of the present invention is within the same dispersion band as the creep crack growth rate data obtained by using the standard compact tensile sample, indicating that the creep crack growth rate data similar to that of the standard sample can be obtained by the small sample creep crack growth test method of the present invention.
In the above test examples, the case of performing the creep crack growth test using the round compact tensile small sample was exemplified, but the creep crack growth rate data similar to that of the standard sample can be similarly obtained even when the compact tensile small sample is used.
In the above test examples, the crack length of the small sample was obtained by the dc potential method, but the same test results were obtained even when the ac potential method was used, and finally creep crack growth rate data similar to that of the standard sample was obtained.
Finally, it should be understood that the above description of the embodiment and the test example is illustrative in all aspects, and not restrictive, and various modifications may be made within the scope not departing from the spirit of the present invention. The scope of the present invention is shown by the claims, not by the above embodiments or test examples. The scope of the present invention includes all modifications within the meaning and range equivalent to the claims.
Industrial applicability of the invention
The small sample creep crack growth test method can obtain the creep crack growth rate data similar to that of a standard sample by using the round compact tensile small sample or the compact tensile small sample, greatly reduces the volume of the required material, reduces the damage of the test material to equipment, and is particularly suitable for the conditions that the sample material is less and the sampling is difficult to be carried out on certain sampling limited occasions such as in-service components, thin-wall parts, welding seams and equipment using functional gradient materials.
Claims (6)
1. A creep crack growth test method for small samples is characterized by comprising the following steps:
s1: taking and preparing small samples for creep crack growth tests from the equipment or the samples;
s2: prefabricating an initial crack on the small sample by using a fatigue testing machine;
s3: welding wires for current input and voltage measurement on the surface of the small sample;
s4: mounting the small sample on a creep crack growth test device, heating the small sample, and applying a load after sufficient heat preservation;
s5: collecting the load line displacement of the small sample by using a displacement extensometer;
s6: obtaining the crack length of the small sample by a direct current or alternating current potential method according to the measured voltage;
s7: processing the test data to obtain creep crack initiation time and creep crack propagation rate,
wherein the small sample is a round compact tensile small sample, the diameter of the small sample is 20mm, the width W of the small sample is 15mm, the thickness B of the small sample is 1-5 mm, and the length a of an initial crack is0The ratio of the width W of the sample to the width W of the sample is 0.3 to 0.8,
in step S7, the creep crack growth rate is characterized by a parameter C calculated by the following formula (2):
where P is the applied load, B is the thickness of the specimen, a is the crack length after propagation, and W is the specimen width; n is a power law creep index and is obtained by testing and fitting the relation between the steady-state creep strain rate and the stress under the log-log coordinate through a creep experiment;
is a creep load linear displacement rate, and is calculated by the following formula (3),
wherein P, B and a are as defined above;
the linear load displacement rate is obtained by time derivation according to a relation curve of the linear load displacement and time; e ═ E/(1-v)2) E is the modulus of elasticity and v is the Poisson's ratio; m is the power law hardening equation εp＝α(σ/σys)mIn (1), alpha is the coefficient of the power-law hardening equation, ∈pIs plastic strain, σ is stress, σysObtaining alpha and m values by fitting the relation between the plastic strain and the stress of the material for yield strength; j. the design is a squarepIs a plastic component, and is calculated by the following formula (4),
wherein P, B, a, W, alpha, m and sigmaysIs as defined above, h of small sample1(a/W,m)Obtained by finite element software calculation.
2. The method for creep crack growth test of a small sample according to claim 1, wherein in step S1, the prepared small sample is subjected to surface grinding, surface polishing and/or electropolishing to remove the surface residual stress of the small sample.
3. The small coupon creep crack growth test method of claim 1, wherein in step S2, the maximum load at the time of pre-cracking is lower than the load applied to the small coupon at the time of testing.
4. The small sample creep crack growth test method according to claim 1, wherein in step S4, the creep crack growth test apparatus is a test apparatus for measuring creep crack growth of the small sample, and the small sample is mounted on the sample loading tray by using a jig such that one end of the small sample is fixed to the sample loading tray and the other end is connected to the sample loading lever.
5. The small coupon creep crack growth test method of claim 1, wherein in step S7, the time corresponding to the creep crack initiation time of 0.2mm crack growth is the creep crack initiation time; the creep crack growth rate is expressed in da/dt and is derived from time t by plotting crack length a against time t using origin software.
6. The small sample creep crack growth test method according to claim 1, wherein in step S6, the crack length of the round compact tensile small sample is calculated using the following formula (1),
where a is the crack length after propagation, W is the specimen width, V0Is the initial voltage and V is the measured voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811493998.8A CN109520856B (en) | 2018-12-07 | 2018-12-07 | Small sample creep crack propagation test method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811493998.8A CN109520856B (en) | 2018-12-07 | 2018-12-07 | Small sample creep crack propagation test method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109520856A CN109520856A (en) | 2019-03-26 |
| CN109520856B true CN109520856B (en) | 2021-04-09 |
Family
ID=65795163
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811493998.8A Active CN109520856B (en) | 2018-12-07 | 2018-12-07 | Small sample creep crack propagation test method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109520856B (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110701988A (en) * | 2019-09-30 | 2020-01-17 | 中车青岛四方机车车辆股份有限公司 | Aluminum alloy sample crack size measuring method |
| CN111175158A (en) * | 2020-02-10 | 2020-05-19 | 天津大学 | Open structure corner fatigue and crack propagation measurement sample |
| CN111638146B (en) * | 2020-05-28 | 2023-04-25 | 中国石油天然气集团有限公司 | Explosion test method for penetrating type cracked steel pipe |
| CN113008679B (en) * | 2021-03-03 | 2023-03-31 | 上海发电设备成套设计研究院有限责任公司 | Creep rate measuring method based on endurance test |
| CN113029826A (en) * | 2021-03-22 | 2021-06-25 | 福州大学 | Method for determining fracture performance of metal material by using pre-notched small punch test sample |
| CN113218750A (en) * | 2021-06-01 | 2021-08-06 | 中南大学 | Method and device for measuring crack propagation speed of rock fracture |
| CN113792470A (en) * | 2021-09-30 | 2021-12-14 | 钢研纳克检测技术股份有限公司 | Method for obtaining calibration function of direct current potential method based on finite element simulation |
| CN114282411B (en) * | 2021-12-23 | 2023-06-20 | 天津大学 | Creep life prediction method for crack-containing welding component |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105466772A (en) * | 2015-11-15 | 2016-04-06 | 北京工业大学 | Multiaxial short crack propagation life prediction method based on critical surface method |
| CN107238531A (en) * | 2017-07-21 | 2017-10-10 | 中国科学院金属研究所 | A kind of device and method of compact tensile specimen crack growth rate measurement |
| CN107402158A (en) * | 2017-07-21 | 2017-11-28 | 中国科学院金属研究所 | Improve the reverse current method of direct current potential drop crack growth rate measurement accuracy |
| CN108458930A (en) * | 2018-03-26 | 2018-08-28 | 华东理工大学 | The method for determining material creep parameter with clamped straight-bar small sample creep test |
-
2018
- 2018-12-07 CN CN201811493998.8A patent/CN109520856B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105466772A (en) * | 2015-11-15 | 2016-04-06 | 北京工业大学 | Multiaxial short crack propagation life prediction method based on critical surface method |
| CN107238531A (en) * | 2017-07-21 | 2017-10-10 | 中国科学院金属研究所 | A kind of device and method of compact tensile specimen crack growth rate measurement |
| CN107402158A (en) * | 2017-07-21 | 2017-11-28 | 中国科学院金属研究所 | Improve the reverse current method of direct current potential drop crack growth rate measurement accuracy |
| CN108458930A (en) * | 2018-03-26 | 2018-08-28 | 华东理工大学 | The method for determining material creep parameter with clamped straight-bar small sample creep test |
Non-Patent Citations (2)
| Title |
|---|
| Effect and mechanism of out-of-plane constraint on creep crack growth behavior of a Cr–Mo–V steel;J.P. Tan, S.T. Tu et al;《Engineering Fracture Mechanics》;20130206;第99卷;第324-334页 * |
| J.P. Tan, S.T. Tu et al.Effect and mechanism of out-of-plane constraint on creep crack growth behavior of a Cr–Mo–V steel.《Engineering Fracture Mechanics》.2013,第99卷 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109520856A (en) | 2019-03-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109520856B (en) | Small sample creep crack propagation test method | |
| Smith et al. | Residual stress analysis in linear friction welded in-service Inconel 718 superalloy via neutron diffraction and contour method approaches | |
| CN111965205B (en) | Sample preparation method for observing SEM+EBSD of nickel-based powder superalloy in-situ sample micro-area | |
| Gangloff et al. | Direct current electrical potential measurement of the growth of small cracks | |
| JP2013092432A (en) | Life estimation of metallic material due to occurrence of stress corrosion crack, and inspection planning system for structure used under corrosive water environment | |
| CN111579397A (en) | Fatigue life prediction method for laser additive manufacturing alloy steel component | |
| CN105043914A (en) | Test method and device for evaluating thermal fatigue of high-temperature alloy | |
| CN111581862A (en) | Equivalent test method for mechanical property of welding joint microcell | |
| CN106041343A (en) | Method for online monitoring resistance change of metal soldered joint | |
| Hassanifard et al. | The effects of residual stresses on the fatigue life of 5083-O aluminum alloy spot welded joints | |
| Suzuki et al. | Change of the effective strength of grain boundaries in Alloy 617 under creep-fatigue loadings at 800 C | |
| CN102944490A (en) | High-temperature rigidity measuring method based on electrified heating | |
| CN111982900B (en) | Experimental method for controlling cooling mode of wire thermal simulation sample | |
| CN105157864B (en) | The measuring method of hollow pole test specimen inner wall temperature | |
| CN110763874A (en) | Method and device for researching metal stress corrosion dynamic process by monitoring pitting corrosion | |
| KR20160038274A (en) | Evaluation method of stress corrosion cracking susceptibility on nickel based alloys | |
| CN107807025A (en) | A kind of method for prefabricating of metal material cycles left life-span specimen surface crackle | |
| CN113790944A (en) | Preparation method of related sample for welding heat affected zone | |
| Lee et al. | Effect of oxide film on ECT detectability of surface IGSCC in laboratory-degraded alloy 600 steam generator tubing | |
| Urbano et al. | The effect of inclusions on fatigue properties for nitinol | |
| Chen et al. | Influence of rapid thermal cycling on the microstructures of single SnAgCu and SnPb solder joints | |
| Zhang et al. | Fatigue crack initiation for Al-Zn-Mg alloy welded joint | |
| CN104820002A (en) | Quenched steel machining white layer detection method based on electrochemical detection device | |
| CN108660411A (en) | A kind of preparation method of the lasting fixture of K002 alloys of heat resistanceheat resistant corrosion infiltration layer | |
| CN116840084A (en) | Method and system for rapidly evaluating stress corrosion sensitivity of fatigue damage component |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |