JPH02165041A - Detection of fatigue damage - Google Patents

Abstract

PURPOSE:To detect the life of a mechanical part by a method wherein an object to be inspected is irradiated with X rays and a half band width and an integration intensity are measured from a profile of intensity of X rays diffracted to determine a half band width, which is compared with a relational expression between the half band width and a life consumption rate. CONSTITUTION:Homogenous X rays are made to irradiate the surface of an object 2 to be inspected from an X-ray generator 1 for a fixed time and intensity of X rays diffracted from the surface thereof is detected with a diffraction X-ray detector 3 varying an angle continuously. The detector 3 outputs a diffraction X ray intensity profile curve to a measuring device 4 to measure a half band width indicated by ab on the profile curve and an integration intensity indicated by an area caebd. The half band width and an integration intensity signal are inputted into an arithmetic device 5 to calculate a half band width normalized. Then, the results are compared with a half band width/(integration intensity)1/2 - life consumption reference diagram obtained from a preliminary test beforehand to detect a life consumption rate thereby achieving a higher reliability and an extended life of mechanical parts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fatigue damage detection method applied to, for example, mechanical parts used under repeated loads.

[Conventional technology]

It has been known for a long time that there is a clear correspondence between fatigue damage and diffraction X-ray half-width.However, in the conventional diffraction The absolute value of was used.

[Problem to be solved by the invention]

When using the diffraction The absolute value is easily affected by variations in positioning accuracy from the X-ray generation source to the Xls irradiation position during measurement.

In other words, if positioning accuracy is poor, the amount of X-rays absorbed by the gas or sample between the X-ray source and the X-ray irradiation position will change, so the total energy of diffracted X-rays will decrease as shown in Figure 6. The integrated strength representing the change changes, and even in the case of the same fatigue damage, the half-width shows different ratio values. In this case, there is a problem that there is a difference between the actual fatigue damage and the damage estimated from the absolute value of the half width, making it impossible to perform a precise damage evaluation.

The present invention seeks to solve the above problems.

[Means to solve the problem]

The present invention irradiates the surface of an object with K Find the normalized half-width from the width and integrated intensity,
The method is characterized in that the lifetime consumption rate is detected by comparing the normalized half-value width with a relational expression or relationship diagram between the normalized half-value width and the lifetime consumption rate that has been created in advance.

[Effect]

In the above, X-rays are irradiated onto the surface of the object from the X-ray generator, and the diffracted X-rays are detected by the diffraction X-ray detector for each diffraction angle. .

The detector sends a diffracted X-ray intensity signal to a measuring device, which measures the half-width and integrated intensity of a profile curve formed by the diffracted X-ray intensity with respect to the diffraction angle. Output the intensity signal to a calculation device.

The arithmetic device calculates the normalized half width using the following equation.

The above-mentioned standardized half-value width is further compared with a relational expression or diagram representing the relationship between half-value @/(integral strength) 9 and life consumption rate, which has been determined in advance using a test piece of the same material through a fatigue test. , the lifetime consumption rate is detected.

As described above, since the normalized half-width obtained by dividing the half-width of the diffraction Moreover, fatigue damage of mechanical parts can be appropriately evaluated non-destructively, and reliability and life extension of mechanical parts can be improved.

〔Example〕

An apparatus used in an embodiment of the present invention will be explained with reference to FIG.

The apparatus shown in FIG. 1 used in this embodiment includes an X-ray generator 1 for irradiating the object 2K with X-rays, a diffraction X-ray detector 3 for detecting the intensity of the X-rays irradiated onto the object 2 and diffracted, A measuring device 4 is provided which inputs a diffracted X-ray intensity signal from a detector 3 and outputs a half-width and integrated intensity signal to an arithmetic device 5.

In the above, monochromatic X-rays are irradiated from the X-ray generator 1 onto the surface of the object 2 for a certain period of time, and the intensity of the X-rays diffracted from the surface of the object 2 is continuously measured by the diffraction is detected by changing the The detector 3 outputs a diffraction X-ray intensity signal forming a diffraction X-ray intensity profile curve as shown in FIG. area caeb
The integrated intensity, denoted by d, is measured.

The half-width and integrated intensity signals are input to the calculation device 5,
The calculation device 5 calculates the half-width normalized by the unit integrated intensity according to the following equation (1)K.

In the arithmetic unit 5, the half-width calculated from the formula (1) Ic and normalized is determined in advance by a preliminary test, and then the half-width/(integral intensity) - life consumption reference line shown in Fig. 5 is calculated in advance. It is compared with the figure and the life consumption rate is detected.

Next, using the device of this example, we will perform a t1 life prediction on the fin end A of the furnace wall of a commercial manual boiler shown in Fig. 3, which is the first part of the boiler that is subject to large fatigue damage. Explain the results of the test.

A fatigue test was conducted by repeatedly applying a tensile load to the fin end A of the furnace wall, and after every 1000 repetitions of the tensile load, X-rays were irradiated using the apparatus of this example and normalized using the above formula (1). Find the half-value width and repeat this 400 times.
The test was repeated up to 0 times and Figure 4 was obtained. From the results obtained from the above test shown in Figure 4, using the half-width/(integral strength) - life consumption standard diagram obtained from the preliminary test conducted in advance and shown in Figure 5, As shown in Table 1 above, the life consumption rate according to this embodiment is within ±10 degrees of the true life consumption rate, which means that the remaining life of mechanical parts, etc. can be detected non-destructively by this embodiment. I understand.

A fatigue test was conducted under the same conditions of half value @/(integral strength) shown in FIG. 5 above, and cracking occurred after 14,825 cycles.

The above number of interruption repetitions (1000 times, 2000 times.

3000 times, 4000 times) to the number of rupture repetitions (1482
Table 1 shows the true life consumption rate divided by 5 times) and the life consumption car evaluated according to this example.

gi table Therefore, this was done.

That is, first, perform a uniaxial fatigue test under arbitrary test conditions to determine the number of repeated ruptures Nf. Next, fatigue tests were conducted under the same conditions as above at 0.05Nf, 01Nf, 02Nf, 0
The test was repeated with interruptions of 5 Nf, and at each interruption point, the surface of the test piece was irradiated with monochromatic X-rays, and the intensity of the X-rays diffracted from the surface was detected by a diffraction X-ray detector.

From the diffraction X-ray intensity at the time of interruption obtained from the above preliminary test, the diffraction X! shown in FIG. ! Create an intensity profile diagram, find the half-width and integrated intensity, and use the above formula (1) K to calculate the life consumption rate of 0.05, 0.1, 0.
2. Find the normalized half-width at 0.5 and create the above figure 5. As a result of the above, since the normalized half-width obtained by dividing the half-width of the diffracted X-ray intensity by the square root of the integrated intensity is used as the evaluation parameter, it is possible to eliminate fluctuations in the life evaluation parameters due to disturbances. , it is possible to appropriately evaluate fatigue damage of mechanical parts in a non-destructive manner, and it is possible to improve the reliability and extend the life of mechanical parts.

〔Effect of the invention〕

The present invention irradiates the surface of an object with X-rays, detects the diffracted X-ray intensity, measures the half-width and integrated intensity of the diffracted X-ray intensity, calculates the normalized half-width, and then Diffraction By dividing the half-width by the square root of the integral strength value and using the normalized half-width, it is possible to eliminate fluctuations in life evaluation parameters due to external disturbances, and to prevent fatigue damage to mechanical parts in a non-destructive manner. It is possible to achieve an appropriate lcf'F value, thereby improving the reliability and extending the life of mechanical parts.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the following equipment used in one embodiment of the present invention;
The figure is an explanatory diagram of the fin end of the furnace wall of the boiler used in the above embodiment, Fig. 3 is an explanatory diagram of the standardized next half width calculation in the above embodiment, and Fig. 4 is an explanatory diagram of the fin end of the furnace wall of the boiler used in the above embodiment. An explanatory diagram of the life prediction test results, Figure 5 is the half price @/ used in the above example.
(Integrated intensity) + - life consumption standard diagram, FIG. 6 is an explanatory diagram of the variation in the half width of diffraction X-rays. 1... X-ray generator, 2... Object, 3... Diffraction X
Line detector, 4... Half width and integrated intensity measuring device, 5...
・Arithmetic equipment. Agent: Akira Sakama, Patent Attorney, 2 people, 1 picture, so to speak, 3rd picture, 1st picture, 1st picture, 1st picture, 1st picture, 1st picture, 5th edition, 5th edition, 2nd book: 1st page, 6th picture: t4th

Claims (1)

[Claims] X-rays are irradiated onto the surface of the object, and the X-rays diffracted from the object are
Detect the line intensity, measure the half-width and integrated intensity from the profile of the diffracted X-ray intensity with respect to the diffraction angle, calculate the normalized half-width from the half-width and the integrated intensity, and calculate the normalized half-width. A fatigue damage detection method comprising: detecting a life consumption rate by comparing the half value width with a relational expression or relationship diagram between the normalized half value width and the life consumption rate created in advance.