CN115901041A - Method for measuring vertical residual stress at joint of head and waist of steel rail section - Google Patents
Method for measuring vertical residual stress at joint of head and waist of steel rail section Download PDFInfo
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- CN115901041A CN115901041A CN202211658725.0A CN202211658725A CN115901041A CN 115901041 A CN115901041 A CN 115901041A CN 202211658725 A CN202211658725 A CN 202211658725A CN 115901041 A CN115901041 A CN 115901041A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 54
- 239000010959 steel Substances 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000005520 cutting process Methods 0.000 claims abstract description 13
- 230000003068 static effect Effects 0.000 claims description 13
- 239000003292 glue Substances 0.000 claims description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- 238000007789 sealing Methods 0.000 claims description 4
- 239000000741 silica gel Substances 0.000 claims description 4
- 229910002027 silica gel Inorganic materials 0.000 claims description 4
- 238000005336 cracking Methods 0.000 abstract description 6
- 238000001514 detection method Methods 0.000 abstract description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000000110 cooling liquid Substances 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 206010016256 fatigue Diseases 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000009662 stress testing Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention provides a method for measuring vertical residual stress at a joint of a head and a waist of a steel rail section, and belongs to the technical field of physical detection. The method provided by the invention comprises the steps of determining the position of a strain gauge at the joint of the head waist of the steel rail section, measuring the initial stress value of the position, and then cutting along the horizontal direction at the position 5mm below the strain gauge, so that the residual stress at the joint of the head waist and the rail along the height direction is completely released, and the residual stress value of the point is measured. The method can accurately measure the vertical residual stress at the joint of the head and the waist of the section of the steel rail, and can be used for predicting the possibility of the steel rail cracking in the vertical direction.
Description
Technical Field
The invention belongs to the technical field of physical detection, and particularly relates to a method for measuring vertical residual stress at a joint of a head and a waist of a section of a steel rail.
Background
At present, the national standard about the reference of the residual stress of the steel rail is mainly iron standard 2344-2012 < 43 kg/m-75 kg/m steel rail ordering technical condition > and American standard AREMA-2011 < American society of railway engineering and maintenance engineers > handbook, wherein the iron standard 2344-2012 only specifies a method for testing the residual stress of the bottom of the steel rail and the maximum allowable value of the residual stress, and does not specify the residual stress of the head and the web of the rail, while the American standard AREMA-2011 specifies the web of the rail in the height direction of the rail, but the method indirectly measures the magnitude of the residual stress of the steel rail in the height direction of the rail by measuring the lateral displacement delta y at the opening of the section of the steel rail, and cannot directly measure the specific value of the residual stress in the height direction of the rail.
Patent document CN113418642A also discloses a method for measuring residual stress of a rail web, but the document discloses a method for detecting vertical residual stress of a rail web, which is not suitable for measuring vertical residual stress at a joint of a head web of a rail section.
The rolling, cooling, straightening and other processes which are carried out on the steel rail in the production process can generate unevenly distributed residual stress inside the steel rail, if the residual stress is too large, early fatigue and brittle failure of the steel rail can be caused, great potential safety hazards are caused to the service of the steel rail, and even in some extreme cases, the steel rail in a quenching state can crack along the height direction on a cooling bed, as shown in fig. 1. The defects are generated because the rail head and the rail bottom surface of the rail generate larger residual stress after the rail is straightened and the residual stress are respectively expressed as tensile stress, the tensile stress generates moments along opposite directions on the section of the rail head, the moment causes the section of the rail to generate different degrees of tensile stress along the high direction, and when the residual stress of the rail head and the rail bottom of the rail is larger, the larger moment is formed along the opposite directions on the section of the rail; meanwhile, the residual stress of the section of the steel rail along the height direction is increased. The section of the joint of the lower jaw of the railhead and the rail web is obviously changed, and stress concentration is easily caused at the joint, so that the steel rail is cracked at the joint. Therefore, it is necessary to detect the vertical residual stress at the joint of the head and the waist of the rail section to estimate the possibility of the rail cracking in the vertical direction.
Disclosure of Invention
In order to overcome the defects of the existing residual stress testing method and test the stress concentration point at the joint of the lower jaw and the web of the steel rail head in a more targeted manner, the invention fixes a strain gauge on the cross section of the steel rail, the strain gauge is fixed at the stress concentration position of the lower jaw of the steel rail head, and then the steel rail is horizontally cut along the longitudinal direction from the position 5mm below the strain gauge to achieve the effect of releasing stress, thereby measuring the magnitude of the residual stress along the vertical direction at the joint stress concentration position of the head web of the cross section of the steel rail, predicting whether the steel rail has the risk of cracking or not by comparing the magnitude relation between the residual stress at the point and the yield strength of a material, and increasing the risk of cracking along the vertical direction when the residual stress is close to the yield strength of the material.
The technical scheme adopted by the invention for solving the technical problem is as follows: and drawing a line at the joint of the head and the waist of the section of the steel rail along the horizontal direction to determine the vertical position of the strain gauge, then drawing a line on the section of the steel rail along the vertical symmetry axis direction, and intersecting the horizontal line at one point, namely fixing the position of the strain gauge. And (3) completely solidifying the glue adhered with the strain gauge, connecting experimental equipment, measuring an initial value, and then cutting the strain gauge along the horizontal direction at a position 5mm below the strain gauge so as to completely release the residual stress at the joint of the head and the waist of the steel rail along the high direction, thereby measuring the residual stress value at the point.
Specifically, the method for measuring the vertical residual stress at the joint of the head and the waist of the section of the steel rail provided by the invention comprises the following steps:
s1: placing a steel rail sample along the vertical direction, wherein the section of the steel rail sample faces upwards;
s2: drawing a straight line 10mm below the tail end of an arc at the joint of the lower jaw of the rail head and the rail waist on the section along the horizontal direction, marking the straight line as a straight line 1, drawing a straight line along a symmetrical axis in the vertical direction, marking the straight line as a straight line 2, marking the intersection point of the straight lines 1 and 2 as an O point, wherein the O point is the position of a fixed strain gauge, drawing a straight line 5mm below the O point along the horizontal direction, and marking the straight line as a straight line 3, namely the starting point of a cutting line;
s3: fixing a strain gauge at an O point along the vertical direction, and sealing the strain gauge;
s4: connecting the fixed strain gauge with a static resistance strain gauge, and clicking a balance button of the static resistance strain gauge to return all initial strain values to 0;
s5: disconnecting the strain gauge from the static resistance strain gauge, and cutting the steel rail sample along the horizontal direction by taking a straight line 3 as a starting point, wherein the cutting length is 600mm, so as to release stress;
s6: and (3) standing the steel rail sample for 4 hours after cutting, connecting the strain gauge with the static resistance strain gauge again, and measuring a final value, namely the residual stress value at the O point after the reading is stable.
In step S1, the length of the rail sample is 1000mm.
In step S3, a strain gauge with the specification of 3mm multiplied by 3mm and the model of BX-120-3AA is fixed at an O point by 406 glue, and after the 406 glue is solidified, 704 silica gel is coated on the surface of the strain gauge to seal and protect the strain gauge.
In step S4, the model of the static resistance strain gauge is AFT-CM-10.
In step S5, a vertical band saw with the model number G5330-50 is adopted to cut the steel rail sample.
The invention has the advantages that the invention can carry out accurate fixed-point measurement of residual stress aiming at the stress concentration position of the steel rail head waist connection part, and compare the experimental result with the yield strength of the material, and the result proves that: when the residual stress at this point reaches over 75% of the yield strength of the material, the rail is very prone to vertical cracking.
Drawings
Figure 1 is a photograph of a crack at the rail head web joint.
FIG. 2 is a schematic cross-sectional structure diagram of a steel rail sample.
Fig. 3 is a schematic three-dimensional structure diagram of a steel rail sample.
Detailed Description
The invention aims to provide a method for accurately measuring the vertical residual stress at the joint of the head and the waist of the section of a steel rail, which is used for estimating the possibility of cracking of the steel rail along the vertical direction.
The present invention will be described in detail below with reference to specific examples, which are intended to facilitate understanding of the present invention and are not intended to limit the present invention.
Example 1: method for measuring vertical residual stress at joint of head and waist of steel rail section
The embodiment provides a method for measuring vertical residual stress at a joint of a head and a waist of a section of a steel rail, which specifically comprises the following steps:
(1) Selecting a section of steel rail sample with the length of 1000mm, and placing the steel rail sample along the vertical direction with the section upward, as shown in figure 2;
(2) As shown in FIG. 2, a straight line is drawn along the horizontal direction at the position 10mm below the arc tail end at the joint of the lower jaw of the rail head and the rail web on the cross section, the straight line is marked as a straight line 1, a straight line is drawn along a symmetrical axis in the vertical direction, the straight line is marked as a straight line 2, the intersection point of the straight lines 1 and 2 is marked as an O point, the O point is the position for fixing the strain gauge, and a straight line is marked as a straight line 3 along the horizontal direction at the position 5mm below the O point (the position is selected to be cut at the position 5mm below the O point because the test verifies that the position can ensure the maximum value of the tensile stress of the rail head on the tread and can also ensure the operability during sawing) and is marked as a starting point of a cutting line;
(3) Fixing a strain gauge of 3mm multiplied by 3mm and BX-120-3AA at an O point along the vertical direction by 406 glue, coating 704 silica gel on the surface of the strain gauge after the 406 glue is solidified, and sealing and protecting the strain gauge so as to prevent a cooling liquid from being immersed in the cutting process to influence an experimental result;
(4) After the 704 sealing silica gel is solidified, connecting the strain gauge with a static resistance strain gauge of an AFT-CM-10 model, and measuring an initial value of the strain gauge at the moment;
(5) After disconnecting the strain gauge from the static resistance strain gauge, as shown in fig. 3, the steel rail sample was horizontally placed on a vertical band saw of type G5330-50, cut 600mm in the horizontal direction with the straight line 3 as the starting point, and released the stress.
(6) And standing for 4 hours after cutting, connecting the strain gauge with the static resistance strain gauge again, and measuring a final value after the reading is stable, namely the residual stress value of the O point.
The method provided by the embodiment can accurately measure the vertical residual stress at the joint of the head and the waist of the section of the steel rail, and the result shows that the vertical residual stress is compared with the yield strength of a steel rail sample: when the residual stress measured by the method provided by the embodiment reaches more than 75% of the yield strength of the steel rail sample, the possibility that the steel rail cracks along the vertical direction is increased, namely the steel rail is easier to crack along the vertical direction.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that various changes, modifications and substitutions can be made without departing from the spirit and scope of the invention as defined by the appended claims. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. A method for measuring the vertical residual stress at the joint of the head and the waist of the section of a steel rail comprises the following steps:
s1: placing a steel rail sample along the vertical direction, wherein the section of the steel rail sample faces upwards;
s2: drawing a straight line 10mm below the tail end of an arc at the joint of the lower jaw of the rail head and the rail waist on the section along the horizontal direction, marking the straight line as a straight line 1, drawing a straight line along a symmetrical axis in the vertical direction, marking the straight line as a straight line 2, marking the intersection point of the straight lines 1 and 2 as an O point, wherein the O point is the position of a fixed strain gauge, drawing a straight line 5mm below the O point along the horizontal direction, and marking the straight line as a straight line 3, namely the starting point of a cutting line;
s3: fixing a strain gauge at an O point along the vertical direction, and sealing the strain gauge;
s4: connecting the fixed strain gauge with a static resistance strain gauge, and clicking a balance button of the static resistance strain gauge to return all initial strain values to 0;
s5: disconnecting the strain gauge from the static resistance strain gauge, and cutting the steel rail sample along the horizontal direction by taking a straight line 3 as a starting point, wherein the cutting length is 600mm, so as to release stress;
s6: and (3) standing the steel rail sample for 4 hours after cutting, connecting the strain gauge with the static resistance strain gauge again, and measuring a final value, namely the residual stress value at the O point after the reading is stable.
2. The method of claim 1, wherein in step S1, the length of the rail sample is 1000mm.
3. The method of claim 1, wherein in step S3, a strain gauge 3mm x 3mm and BX-120-3AA is fixed at the point "O" with 406 glue, and after the 406 glue is solidified, the surface of the strain gauge is coated with 704 silica gel to seal and protect the strain gauge.
4. The method according to any one of claims 1 to 3, wherein in step S4 the static resistance strain gauge is of the type AFT-CM-10.
5. The method according to any one of claims 1 to 4, wherein in step S5, the rail sample is cut using a vertical band saw of type G5330-50.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211658725.0A CN115901041A (en) | 2022-12-22 | 2022-12-22 | Method for measuring vertical residual stress at joint of head and waist of steel rail section |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211658725.0A CN115901041A (en) | 2022-12-22 | 2022-12-22 | Method for measuring vertical residual stress at joint of head and waist of steel rail section |
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| CN115901041A true CN115901041A (en) | 2023-04-04 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202211658725.0A Pending CN115901041A (en) | 2022-12-22 | 2022-12-22 | Method for measuring vertical residual stress at joint of head and waist of steel rail section |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104535231A (en) * | 2015-01-05 | 2015-04-22 | 攀钢集团攀枝花钢铁研究院有限公司 | Resistance strain gauge switching device for testing steel rail residual stress and testing method |
| CN113418642A (en) * | 2021-05-14 | 2021-09-21 | 包头钢铁（集团）有限责任公司 | Test method for accurately detecting vertical residual stress of rail web of steel rail |
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2022
- 2022-12-22 CN CN202211658725.0A patent/CN115901041A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104535231A (en) * | 2015-01-05 | 2015-04-22 | 攀钢集团攀枝花钢铁研究院有限公司 | Resistance strain gauge switching device for testing steel rail residual stress and testing method |
| CN113418642A (en) * | 2021-05-14 | 2021-09-21 | 包头钢铁（集团）有限责任公司 | Test method for accurately detecting vertical residual stress of rail web of steel rail |
Non-Patent Citations (1)
| Title |
|---|
| 丁韦 等: "贝氏体钢轨闪光焊水平裂纹形成原因分析", 《热加工工艺》, vol. 49, no. 21, 30 November 2020 (2020-11-30), pages 159 * |
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