JP2544008B2 - Railway laying rail evaluation method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for measuring a fatigue progress state of an actually laid rail of a railway and evaluating a remaining life.

[Prior Art] Generally, in railway rails, the cumulative tonnage is used as a measure of fatigue damage occurrence. For example, when the cumulative tonnage of high-speed rails of 100 km / hr or more reaches about 300 million tons,
Fatigue damage suddenly occurs near the center of the rail head surface, which is the contact surface between the wheel and the rail. On the other hand, that of ultra high-speed railways over 200 km / hr is about 150 million tons. This is due to the difference in running conditions between high-speed rail and ultra-high-speed rail. Therefore, even if the cumulative tonnage, which is a conventional fatigue damage generation scale, is the same, it means that the fatigue progress state changes when the conditions such as running and environment are different.

Therefore, in order to predict the life of an actually laid rail, it is essential to evaluate the actual state of fatigue progress under a wide variety of conditions and extract fatigue parameters. However, conventionally, there was no means for directly evaluating the fatigue progress state on the actually laid rail, so the rail was removed from the track and the investigation was conducted in a laboratory.

However, at present, it is impossible to remove a large number of actually laid rails, and various material tests (for example, hardness measurement) and physical tests (for example, residual stress and texture measurement) have been carried out only on a few sampling rails. Moreover, this test merely clarified the actual condition of the laid rail with a certain cumulative tonnage. Therefore, conventionally, it has not been possible to evaluate the degree of fatigue progress of an actually laid rail and predict the remaining life.

[Problems to be Solved by the Invention] An object of the present invention is to show the degree of fatigue progress and the degree of damage on the surface of an actual laying rail head that differs in running or laying environment.
The purpose is to extract line parameters and predict the remaining life of rails installed anywhere.

[Means and Actions for Solving the Problems] The X-ray diffraction method is a useful means for clarifying the fatigue progress state of the material, but the conventional commercial X-ray diffractometer has not been made easy. However, it was extremely difficult to apply it to an arbitrary location on an actual laying rail and extract the X-ray parameter of the fatigue process.

However, the present inventors have already applied a compact X-ray diffractometer that can be applied to an arbitrary place on an actually laid rail and a method of using the same (Japanese Patent Application No.
-20298)). The present invention is based on this "small X
The line diffractometer and its usage "are applied to many actual laying rails with different running or laying environments, and the contact direction with the wheel, that is, the rail head surface including the welded part, Fix the X-ray goniometer at the measurement position where the X-ray parameters are obtained, and inject the characteristic X-ray of Cr, Fe, or Co into the contact surface between the rail and the wheel, and specify the incident X-ray and the detector in the specific crystal plane. Diffracted X-rays are detected by the ψ-constant method (constant diffractive surface method) that operates simultaneously on the opposite sides at the same speed with the normal as the center, and the integrated intensity (area of the diffracted X-ray figure) at each cumulative tonnage is calculated. A width (integrated intensity / peak intensity) is used as an X-ray parameter of fatigue progress, and a relationship diagram between the changes and the life ratio, that is, a master curve is created in advance.

The master curve can be created from a rail wear test using a high-speed rail tester, in addition to the actual laying rail. That is, a high-speed rail tester equipped with the same rail as the actual laying rail is operated at a constant cumulative tonnage to irradiate the contact surface between the rail and the wheel with incident X-rays, and diffracted X-rays by the ψ constant method. It can also be created by detecting and obtaining the X-ray parameters of the integrated intensity and the integrated width at each cumulative tonnage. Then, under the same measurement conditions as when the master curve was created, incident X-rays were applied to the actual rail head surface requiring diagnosis, and the integrated intensity and integration width obtained from the diffracted X-rays emitted were related to the master curve. It is a railway rail evaluation method characterized by predicting the fatigue, damage degree and remaining life of the rail.

 The details of the present invention will be described below.

The inventors actually brought in the above-mentioned “small X-ray diffractometer” on the track and radiated incident X-rays on the head surface of many actual laying rails with different running environments or laying environments for each cumulative tonnage, and diffracted. Diffracted X-rays radiated from the head surface were detected under the condition that the surface normal was constant, and the fact that the X-ray parameters of fatigue progression due to repeated contact between the wheel and the rail were found to be in the integrated intensity and integrated width was found. The present invention has been completed by

That is, in the present invention, as the fatigue due to the contact between the wheel and the rail progresses, the {111} orientation component reaches the final stable orientation of {200} orientation via the {211} orientation component. By measuring X-rays and 200 diffraction X-rays, the amount of {211} orientation and {200} orientation is measured to evaluate the fatigue level. The procedure is to first install a small X-ray diffractometer on the laying rail, and detect diffracted X-rays from the {211} or {200} crystal plane parallel to the rail head surface on the rail surface that contacts the wheel. Irradiate characteristic X-rays such as Cr, Fe or Co at an incident angle, and measure 211 diffraction X-rays or 200 diffraction X-rays by the constant ψ method. Then, after the measurement of the diffracted X-rays, the integrated width and the diffracted integrated intensity of the diffracted X-rays are obtained by an arithmetic device included in the small X-ray diffractometer, and the analysis result is compared with the master curve to obtain the remaining life. is there.

 The method of creating the master curve will be described below.

Fig. 1 is an example of a high-speed rail rail that suffers from damage of 550 million tons due to abrupt fatigue damage with cumulative 300 million tons or more of the present invention, and has a life ratio (accumulated tonnage / rail breakage etc.). 211 diffracted X against the cumulative tonnage of each, or each cumulative tonnage / cumulative tonnage of the actual laying rail to be replaced with a new one)
It is a master curve of the integrated intensity ratio and integrated width of a line. Here, the integrated intensity ratio of the 211 diffraction X-rays refers to the amount of the integrated intensity of the 211 diffraction X-rays of the used rail with respect to the integrated intensity of the 211 diffraction X-rays of the unused rail. This master curve is obtained by measuring 211-diffraction X-rays at a plurality of positions on the rail head surface for rails having different life ratios and plotting the integrated intensity and the integral width with respect to each life ratio. That is, this master curve directly represents the degree of fatigue and damage progression on the head surface of the actual laying rail.

The actual surface of rails with a life ratio of 0.45 (cumulative tonnage of 300 million tons) or less was measured on the head surface without any fatigue damage. The position of maximum fatigue damage on the head surface was measured for an actually laid rail with a life ratio of 0.45 (cumulative tonnage: 300 million tons) or more. Further, in the master curve of FIG. 1, among the many measured values at each life ratio, the minimum integrated strength and the maximum integrated width corresponding to the place where fatigue is most advanced are entered in consideration of safety. This is because when the life ratio of high-speed railway rails increases, the frequency of slipping between the wheels and the rails increases, and not only the top surface wears but also the transformation amount of the white layer (martensite) due to rapid heating and quenching increases. As the fatigue of the white layer and matrix progresses, and fatigue damage occurs from the white layer and its vicinity, leading to rail breakage, the X-ray diffraction from the white layer with the most fatigue of the rail and its vicinity is generated. Of these, the actual measurement value corresponding to the state in which fatigue is most advanced is selected in consideration of safety. In other words, the integrated intensity of 211 diffracted X-rays preferentially forms the {111} orientation component in the white layer due to the transformation, but when the {211} orientation component of the matrix reaches the stable orientation {200} orientation component with fatigue. At the same time, the white layer {11
The 1} direction component also tends to decrease because it reaches the {200} direction component via the {211} direction component. Further, the integration width of the 211-diffraction X-ray tends to become larger because the dislocation density of the white layer itself is high and non-uniform strain is introduced by the progress of fatigue. In other words, FIG. 1 shows the measured values of the positions where the whitest layer was formed most in each life ratio and the fatigue of the formed white layer and the matrix was most advanced. Since the two X-ray parameters of fatigue naturally change depending on the rail type and manufacturing conditions, when writing on the master curve, the maximum, minimum, and average values of the measured values are selected at appropriate times. That is, in the present invention, a master curve is created for each rail type and manufacturing condition.

Therefore, according to the present invention, at least one of two fatigue X-ray parameters is determined for an actual laying rail whose cumulative tonnage of a high-speed rail is unknown, or whose fatigue state is unknown even if the cumulative tonnage is known. By actually measuring and applying it to the master curve of FIG. 1, the life consumption rate can be known, and the remaining life can be easily obtained from the proportional distribution relationship. The life consumption rate is a ratio of life obtained by comparing the integrated intensity measured at the time of diagnosis or the integration width with a master curve and expressed as a percentage.

Fig. 2 is distributed in parallel to the rail head surface of the present invention {20
It is a master curve of the integrated intensity change of the diffracted X-ray from the 0} crystal plane. In this figure, many actual laying rails with different running or laying environments are actually measured, and the value with the highest integrated strength at each life ratio is entered. It is {11
This is because the white layer in which the 1} orientation component has developed finally reaches the {200} orientation component due to crystal rotation as the life ratio increases. Therefore, the X-ray parameter from the {200} crystal plane also directly indicates the degree of fatigue or damage progress of the actual laying rail as in FIG. 1, and can be used as a master curve for predicting the remaining life of the laying rail. .

The master curves in FIGS. 1 and 2 are prepared by measuring 211 diffraction X-rays and 200 diffraction X-rays of the same standard product.

In addition, the integrated intensity for the 211-diffraction X-ray in Fig. 1 is in the middle of the crystal rotation {211} because the crystal rotation from the {111} crystal plane to the {200} crystal plane increases due to the increase of the life ratio.
Since the number of crystal planes decreases, the integrated intensity of 211 diffracted X-rays decreases with the life ratio, as shown in FIG.

Further, the integrated intensity ratio for the 200 diffraction X-rays in FIG. 2 is an amount defined by the diffracted X-ray intensity of the used rail with respect to the integrated intensity of the unused rail diffracted X-ray,
As shown in FIG. 4, as the integrated intensity increases, the integrated intensity ratio also increases with the life ratio.

Furthermore, as shown in FIG. 5, the integrated width for the 200 diffraction X-rays in FIG. 2 increases not only with {200} crystal planes due to rail fatigue but also due to increase in non-uniform strain, as shown in FIG. The integration width also increases with the life ratio.

In addition, the running conditions of the ultra-high-speed rail are particularly different from those of the high-speed rail, and a white layer is not formed on the head surface due to the increase in the life ratio, but due to the diffracted X-rays from the rail base material,
Similarly, when the integrated strength and the integrated width are taken, the same relationship with the life ratio as that of the high-speed railway can be obtained, so that the life of the actually laid rail can be predicted.

[Examples] (Example 1) The remaining service life of an actually laid rail of private railway company A was evaluated. The target rail was a 50kgN ordinary rail whose cumulative tonnage was unknown and was 25m long. The integration width was measured using a small X-ray diffractometer, and the measurement condition was that the characteristic X-ray of Cr (30 Kv, 10 mA) was irradiated on the rail head surface by the constant ψ method, and the 211 diffraction line of Fe was measured. The measurement was concentrated on the region where the white layer was remarkable. As a result, the integrated value was in the range of 1.7 to 1.8. Then, when the maximum value was applied to the master curve of FIG. 1, the life consumption rate was 0.70. The remaining cumulative tonnage of this rail is equivalent to 165 million tons, and it was predicted that it could be used for another 9 years and 3 months due to running and laying environmental conditions.

(Example 2) The remaining service life of an actually laid rail of private railway company B was diagnosed. The target rail was a 50kgN ordinary rail with a cumulative tonnage of 500 million tons or more and a length of 50m. The integrated intensity was measured using a small X-ray diffractometer. The measurement condition was that the characteristic X-ray of Fe (30Kv, 10mA) was irradiated on the rail head surface, and from the {200} crystal plane distributed parallel to the head surface. The integrated intensity of the diffracted X-ray of was obtained. The measurement was conducted intensively in the vicinity of fatigue damage. As a result, the integrated intensity was in the range of 6.65 to 6.80 KC. Therefore, when the maximum value is applied to the master curve in Fig. 2, the life consumption rate is 97%. Therefore, it was predicted that this rail would need to be immediately replaced with a new rail due to running conditions and installation environment.

[Effects of the Invention] As described above, according to the railway rail evaluation method of the present invention, fatigue and damage of the rail can be evaluated, and the remaining life thereof can be predicted. It is useful information, and its effect is great.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a master curve of integral width and integral intensity change with respect to life ratio for remaining life evaluation of conventional rails. The figure also shows the occurrence of fatigue damage and the damage state. Fig. 2 shows 20 against the life ratio of the remaining life evaluation of conventional rails.
0 This is a master curve for changes in integrated intensity. The figure also shows the occurrence of fatigue damage and the damage state. FIG. 3 is a diagram showing the integrated intensity for the 211-diffraction X-ray of FIG. 1 in relation to the life ratio. FIG. 4 is a diagram showing the integrated intensity ratio for the 200 diffraction X-rays in FIG. 2 in relation to the life ratio. FIG. 5 is a diagram showing the integral width for 200 diffraction X-rays in FIG. 2 in relation to the life ratio.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideaki Kageyama 1-1-1 Edamitsu, Yawatahigashi-ku, Kitakyushu, Fukuoka Prefecture, Nippon Steel Corporation Yawata Works (56) Reference US Patent 4287416 (US, A) US Patent 4686631 (US, A)

Claims (4)

(57) [Claims] 1. An X-ray goniometer fixed at a measuring position on the surface of a rail head that has been actually laid, irradiates an incident X-ray on a white layer or matrix generated on the surface of the laid rail head. , Diffraction X radiated under the condition that each diffractive surface normal from the white layer or matrix is constant
The integrated intensity of the line, at least one X-ray parameter of the integrated width is measured, and the fatigue of the rail and the degree of damage are evaluated from the comparison with the master curve created in advance by measuring the X-ray parameter under the same measurement conditions. Or rail life laying rail evaluation method characterized by predicting life. 2. X-rays having an integrated intensity and an integrated width of diffracted X-rays which are radiated under the condition that an incident X-ray is radiated on a surface of a laid rail head having a different cumulative tonnage and a diffracting surface normal becomes constant.
The rail laying rail evaluation method according to claim 1, wherein a line curve is obtained and a master curve representing a relationship between the X-ray parameter and fatigue, damage or life of the laying rail is created. 3. An incident X-ray is irradiated onto a {200} crystal plane distributed in parallel to the head surface of a laying rail having a different cumulative tonnage,
The integrated intensity of 200 diffracted X-rays emitted under the condition that the diffractive surface normal is constant is obtained, and a master curve showing the relation between the 200 diffracted X-ray integrated intensity and fatigue, damage or life of the laid rail is calculated. The railway laying rail evaluation method according to claim 1 or 2, which is created. 4. The rail laying rail evaluation method according to claim 1, wherein a master curve is created by changing a cumulative tonnage of the laying rail with a high-speed rail testing machine.