JP2000074887A - Ultrasonic inspection method for joined material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To nondestructively estimate a joining characteristic of a joined material such as strength and tenacity, and to provide high estimation precision for the joining characteristic. SOLUTION: An angled probe 5 for transmission and an angled probe 6 for reception are arranged in one side of a joined interface 4 of a joined material 1, and the presence of a defect in the interface 4 is judged based on the intensity of a reflected wave reflected by the interface 4. An angled probe 7 for transmission is arranged in one side of the interface 4 of the material 1 where the presence of no defect in the interface 4 is judged, and an angled probe 8 for reception is arranged in the other side to measure an attenuation amount of an ultrasonic wave transmitted through the interface 4. The measured attenuation amount in the joined material 1 is compared with an attenuation amount of an ultrasonic wave transmitted through a joined interface of a standard joined body joined under a known condition, so as to estimate a joining characteristic of the joined material 1 based on a correlation between the preliminarily measured attenuation amount of the ultrasonic wave transmitted through the interface of the standard joined body and a characteristic of the standard joined body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic inspection method for a joining material, and more particularly, to a joining characteristic such as a joining temperature and strength of a joining material from an attenuation amount of an ultrasonic wave transmitted through a joining interface of the joining material. The present invention relates to an ultrasonic inspection method for a bonding material for non-destructively inspecting a bonding material.

[0002]

2. Description of the Related Art A metal joining method is a processing method in which one member is added to another member, and a metallurgical joining method in which energy is locally applied to bond a separate object to each other, It is roughly divided into mechanical joining methods such as bolt joining.

[0003] Metallurgical joining methods are further classified into a fusion welding method, a pressure welding method, a brazing method, a diffusion joining method, and the like. The fusion welding method
This is a joining method in which a joined portion of a base material is heated to a molten state, and a filler material is added and fused as needed. The pressure welding method is a method of joining by applying a large mechanical pressure to the material to be joined,
In addition to room temperature welding, friction welding, explosion welding, ultrasonic welding, etc., resistance welding is also included in this category. The brazing method is a method in which a brazing material having a melting point lower than that of a material to be joined is caused to flow into a gap of a joining portion in a molten state and solidified for joining.

In the diffusion bonding method, the materials to be joined are brought into close contact with each other, pressurized at a temperature equal to or lower than the melting point of the materials to be joined so as not to cause plastic deformation, and utilizing the diffusion of atoms generated at the joining interface. It is a method of joining the materials, the solid-state diffusion bonding method that directly adheres the materials to be joined and diffuses elements while maintaining the solid state, and inserting a low melting point insert material between the materials to be joined, There is a liquid phase diffusion bonding method in which an insert material is temporarily melted, and a specific element in a liquid phase is diffused and disappeared into a material to be bonded, and is solidified isothermally to perform bonding.

The metallurgical joining method such as the diffusion joining method, unlike the mechanical joining method, can save materials and reduce man-hours, and is excellent in joining strength, airtightness, pressure resistance and the like. There is an advantage that an improved joint can be obtained. On the other hand,
The joining operation is irreversible, and it is difficult to separate and rejoin after joining. Further, there is a defect that bonding characteristics such as strength and toughness greatly vary due to various defects generated at the bonding interface, and moreover, the causes of the defects are various.

For this reason, in a metallurgical bonding method such as a diffusion bonding method, when high reliability is required, a radiation transmission test, an ultrasonic wave test, and an ultrasonic Various non-destructive inspections such as a flaw detection test, a magnetic particle flaw detection test, and a penetrant flaw detection test are performed on bonding materials. When the same type of bonding material is mass-produced, a part of the mass-produced bonding material is extracted, a test piece including a bonding interface is cut out from the bonding material, and a destructive inspection such as a tensile test is performed. ing.

[0007]

However, a metallurgical joining method such as a diffusion joining method involves local heating and cooling of a metal material to be joined, so that a structure or a mechanical property near a joint is required. In some cases, a heat-affected zone in which the temperature has changed may occur. Therefore, cracks, pores,
Even when no defect such as poor bonding is found, the bonding characteristics such as bonding strength and toughness may be reduced.

[0008] In this case, when the joining material is mass-produced, a destructive test by sampling inspection is possible.
For example, during small-scale production such as plant manufacturing, a destructive test by sampling inspection is impossible. In addition, the joint material actually joined contains both defects such as cracks, pores, joint failure, and the heat-affected zone, and a means for inspecting the joint characteristics of such a joint material with high accuracy is required. There was no problem.

[0009] In order to solve this problem, for example, a means for manualizing the joining operation can be considered. However, in addition to the fact that the joining characteristics depend on many joining conditions such as joint design, accuracy, cleanliness, joining temperature, holding time, pressure, etc., when joining work must be performed outdoors In addition, it is affected by weather such as temperature, temperature, etc., and further greatly depends on the skill of the joining operator. Therefore, especially for bonding materials used in areas where high reliability is required,
It is not enough to just manage the joining operation.

The problem to be solved by the present invention is that in a metallurgical joining method such as a diffusion joining method, it is possible to non-destructively estimate joining properties such as strength and toughness of a joining material. It is an object of the present invention to provide a method for inspecting a joining material with high estimation accuracy of joining characteristics.

[0011]

In order to solve the above-mentioned problems, an ultrasonic inspection method for a bonding material according to the present invention comprises: one or more oblique probes on one side of a bonding interface of the bonding material; Is arranged, ultrasonic waves are incident from the oblique probe toward the bonding interface of the bonding material, the intensity of a reflected wave reflected from the bonding interface is measured, and the intensity of the reflected wave is used to determine the bonding interface. A flaw detection step for determining whether or not a defect is present in the bonding material, and a transmission oblique angle probe on one side of the bonding interface of the bonding material determined to have no defect at the bonding interface by the flaw detection step. A probe and a bevel probe for reception are arranged on the other side, respectively, and ultrasonic waves transmitted from the bevel probe for transmission pass through the bonding interface, and the oblique probe for reception is disposed. Measures the amount of attenuation of the ultrasonic wave when it is received by the angular probe, and measures in advance based on the measured value. From correlation between ultrasonic attenuation and the bonding properties of the bonded standard conjugate by known bonding conditions,
And an inspection step of inspecting the joining characteristics of the joining material.

The term "joining characteristics" as used herein refers to any characteristics that affect the mechanical properties of the joining material, and include defects other than defects such as cracks, pores, and poor joining formed at the joining interface. Specific examples include joining conditions such as joining temperature, cooling rate, and heat treatment temperature, mechanical properties such as joining strength, yield stress, hardness, and toughness, and material properties such as composition and crystal grain size. In particular, in structures where stress is applied, the bonding strength is the most important evaluation item, and since the bonding temperature has the greatest effect on the bonding strength, the bonding characteristics include the bonding temperature or the bonding strength. It is desirable to choose.

Further, the inspection step may be applied to the bonding material determined to have no defect at the bonding interface in the flaw detection step, and the bonding characteristics of the bonding material may be estimated. The determination of the presence or absence of a defect in the flaw detection step and the estimation of the bonding characteristics in the inspection step may be performed simultaneously.

According to the ultrasonic inspection method for a bonding material according to the present invention having the above-described structure, one or more oblique probes arranged on one side of the bonding interface are used to reflect light from the bonding interface. The presence or absence of a defect at the bonding interface is determined by measuring the intensity of the ultrasonic wave to be applied. Next, a transmission angle beam probe is arranged on one side of the bonding interface of the bonding material determined to have no defect, and a reception angle beam probe is arranged on the other side of the bonding material. The attenuation of the ultrasonic wave passing through is measured.

Since the attenuation of the ultrasonic wave transmitted through the bonding material is affected by the change in the bonding characteristics near the bonding interface, if the bonding characteristics change due to a change in the thermal history, the ultrasonic wave transmitted through the bonding interface will change. Is detected as an increase or decrease in the amount of attenuation.

Therefore, when comparing the attenuation of the ultrasonic wave transmitted through the bonding interface of the actually bonded bonded body with the attenuation of the ultrasonic wave transmitted through the bonding interface of the standard bonded body having known bonding conditions, The joining characteristics of the actually joined joining materials can be estimated based on the correlation between the attenuation of the standard joined body measured in advance and the joining characteristics.

Further, when the attenuation of the transmitted wave is measured in a state where a defect such as a crack or a pore exists at the joint interface, the ultrasonic wave is reflected by the defect. Therefore, as compared with the case where there is no defect or the like, the attenuation of the transmitted wave increases, and the accuracy of estimating the bonding characteristics decreases. However, in the present invention,
Before measuring the attenuation of the transmitted wave, the presence or absence of a defect is determined in the flaw detection process, and the attenuation of the transmitted wave is measured for the bonding material determined to be free of defects, so that the change in the bonding characteristics It is possible to estimate with high accuracy.

Further, since the ultrasonic waves have high directivity, if the interval between the oblique probes is proper, the ultrasonic waves transmitted from the plurality of oblique probes will not interfere with each other. for that reason,
An oblique probe for measuring a reflected wave and an oblique probe for measuring a transmitted wave can be arranged on a bonding material, and the detection of a defect and the estimation of the bonding characteristics can be performed simultaneously. Thereby, the inspection time is shortened, and the efficiency of the bonding process is improved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail. An ultrasonic inspection method for a bonding material according to the present invention includes a flaw detection step and an inspection step. FIG.
FIG. 3 is a schematic configuration diagram illustrating an example of a flaw detection process. In FIG. 1, a joining material 1 is formed by joining steel pipes 2 and 3 at pipe end faces. A transmitting probe 5 and a receiving probe 6 are arranged on one side of a joining interface 4.

As shown in FIG. 2, the transmission probe 5 is a so-called angle probe in which a vibrator 11 is attached to a wedge 10 made of a synthetic resin such as acrylic. Electrodes are attached to both surfaces of a thin plate made of a piezoelectric material such as lead niobate or lead zircon titanate. Also,
A sound absorbing material 12 is attached to the wedge 10 so that the ultrasonic wave reflected on the contact surface between the transmitting probe 5 and the bonding material 1 can be absorbed.

The shape of the bottom surface of the transmission probe 5 is desirably flat when inspecting a plate-like bonding material.
As shown in FIG. 1, when inspecting a bonding material 1 having a curved surface such as a steel pipe, the shape of the bottom surface of the transmission probe 5 may be a curved surface according to the curvature of the bonding material 1. Although not shown, the receiving probe 6 has the same structure as the transmitting probe 5.

In addition, it is necessary to interpose a couplant in the gap between the transmitting probe 5 and the receiving probe 6 and the bonding material 1. This is because if there is a gap between the transmission probe 5 or the reception probe 6 and the bonding material 1, transmission and reception of ultrasonic waves are not performed efficiently. The couplant may be any one that can efficiently transmit ultrasonic waves, and various couplants may be used as needed. Examples of the couplant include water, oil, and glycerin.

Further, in order for the receiving probe 6 to catch the ultrasonic wave that has entered the steel pipe 2 from the transmitting probe 5 and is reflected by a defect existing at the joint interface 4, the transmitting probe 5 and the receiving probe It is necessary to set the relative position of the contact 6 accurately. The ultrasonic wave incident on the steel tube 2 from the transmission probe 5 and reflected by the defect propagates while repeating total reflection on the outer and inner peripheral surfaces of the steel tube 2. 2 must be placed at a position where the ultrasonic wave totally reflected on the inner peripheral surface of the steel pipe 2 reaches the outer peripheral surface of the steel pipe 2 or at a position where the ultrasonic wave totally reflected on the outer peripheral surface of the steel pipe 2 reaches the inner peripheral surface of the steel pipe 2. .

The ultrasonic wave totally reflected on the outer peripheral surface of the steel pipe 2 is totally reflected on the inner peripheral surface of the steel pipe 2, and the horizontal distance until reaching the outer peripheral surface of the steel pipe 2 again is one skip. Whether to arrange the receiving probe 6 may be appropriately selected according to the shape of the bonding material 1 to be inspected and measurement conditions. In the case of FIG. 1, the receiving probe 6 is arranged at a position of the third skip from the position where the ultrasonic wave reflected by the defect existing at the joint interface 4 is first totally reflected on the outer peripheral surface of the steel pipe 2.

Next, a method for detecting a defect existing at the bonding interface 4 of the bonding material 1 will be described. First, a synchronization controller (not shown) generates a high-frequency pulse, and sends the high-frequency pulse to the transmission probe 5 via a high-frequency cable. The high-frequency pulse sent to the transmission probe 5 is applied to electrodes attached to both surfaces of the vibrator 11, whereby the vibrator 11 expands and contracts in the thickness direction, and generates ultrasonic waves.

The generated ultrasonic waves enter the steel pipe 2 through the wedge 10, are totally reflected once on the inner peripheral surface of the steel pipe 2, and then enter the bonding interface 4. When there is no defect in the bonding interface 4, the ultrasonic wave passes through the bonding interface 4 as it is,
When a defect such as a crack or a pore exists, the ultrasonic wave is totally reflected by the defect and reaches the outer peripheral surface of the steel pipe 2.

The ultrasonic wave that has reached the outer peripheral surface of the steel pipe 2 further propagates toward the receiving probe 6 arranged on the steel pipe 2 while repeating total reflection on the inner and outer peripheral surfaces of the steel pipe 2. Then, the ultrasonic wave reflected at the bonding interface 4 by the receiving probe 6 is received.

The received ultrasonic wave is transmitted to the transducer provided on the receiving probe 6, and expands and contracts the transducer in the thickness direction. The mechanical vibration is converted into an electric signal by the vibrator and sent to a receiving unit of an inspection device (not shown) via a high-frequency cable. Then, the intensity of the reflected wave is obtained from the magnitude of the electric energy received by the receiving probe 6.

At this time, the distance between the transmitting probe 5 and the receiving probe 6 is set to a fixed distance (for example, a distance corresponding to 3 skips).
If it is scanned back and forth and left and right while maintaining the position, the position through which the ultrasonic wave is transmitted changes, so that the presence or absence of a defect can be checked on the entire bonding interface 4. The scanning method includes various methods such as zigzag scanning, front / rear scanning, left / right scanning, and is not particularly limited, and may be appropriately selected according to the shape of the bonding material 1 or the like.

Since the scanning distance only needs to cover the entire surface of the bonding interface 4, in the direction perpendicular to the bonding interface 4, the scanning may be performed by a distance corresponding to at least 0.5 skips. The direction parallel to the joining interface 4 is at least a distance corresponding to the width of the joining interface 4 in the case of a plate-like joining material, and at least the pipe circumference in the case of a tubular joining material as shown in FIG. What is necessary is just to scan by a corresponding distance.

If the intensity of the reflected wave is at the level of the noise echo, it is determined that there is no defect in the bonding interface 4 and
Proceed to the next inspection step. On the other hand, if the intensity of the reflected wave exceeds the noise echo level, there is a high possibility that a defect exists at the bonding interface 4, and the inspection is interrupted, and other measures such as performing non-destructive inspection are taken. Will be taken.

In the flaw detection step, it is preferable to use ultrasonic waves in the transverse wave mode. However, when flaw detection is performed on the bonding material 1 made of a material having a large attenuation of the ultrasonic waves, ultrasonic waves in the longitudinal wave mode are used. Is also good.

The refraction angle and frequency of the ultrasonic wave incident on the steel pipe 2 from the transmission probe 5 and the sizes of the transmission probe 5 and the reception probe 6 are determined by the shape of the joint material 1 to be measured. The optimum value may be selected according to the physical properties and the like. Also, in the example shown in FIG. 1, the flaw detection process using two oblique probes is shown. However, ultrasonic waves are incident on the defect directly from the transmission probe 5 and reflected by the transmission probe 5. Defect detection may be performed using a single probe method that captures waves.

Further, two or more transmission probes 5 and two or more reception probes 6 may be arranged. Since the ultrasonic waves have good directivity, if the intervals between the transmission probes 5 are appropriate, the ultrasonic waves incident from each transmission probe 5 will not interfere with each other. Therefore, when flaws are detected in a bonding material having a large area of the bonding interface 4, if two or more probes are provided, the scanning distance becomes shorter and the flaw detection time can be shortened.

Next, the inspection process will be described. FIG.
FIG. 2 is a schematic configuration diagram illustrating an example of an inspection process. In FIG. 3, the bonding material 1 is determined to have no defect at the bonding interface 4 in the above-described flaw detection process. Further, a transmission probe 7 and a reception probe 8 are arranged with the bonding interface 4 of the bonding material 1 interposed therebetween.

Here, the transmission probe 7 and the reception probe 8
Is an oblique probe having a configuration similar to that of the transmission probe 5 shown in FIG. 2, and thus detailed description is omitted, but the transmission probe 7 and the reception probe 8 used in the inspection process are omitted. It is preferable to use a square probe having one side of 8 mm or more and 15 mm or less.

This is because, when compared with the same area, the square probe has better directivity and the measurement sensitivity is better than the round probe. In addition, one side of the square probe is 8 mm
If it is less than 1, the directivity angle increases and the directivity decreases, which is not preferable. The larger the probe, the smaller the directivity angle and the better the directivity.However, if the length of one side exceeds 15 mm, the limit distance of the short-range sound field increases and a strong interference phenomenon occurs in the short-range sound field. This is not preferable because noise increases.

The ultrasonic waves incident on the material are longitudinal waves,
Although it propagates in various modes such as a shear wave, a surface wave, and a plate wave, it is preferable to use a longitudinal wave in the inspection process. This is because, in the ultrasonic wave in the longitudinal wave mode, the attenuation of the ultrasonic wave transmitted through the bonding interface 4 greatly changes with the change in the bonding characteristics, and the reliability of the inspection result of the bonding characteristics can be improved. .

However, in the case of using the ultrasonic wave of the longitudinal wave mode, it is necessary to enter the bonding material 1 so that the refraction angle is 17 ° to 30 °. If the angle of refraction is less than 17 °, noise increases and the S / N ratio decreases. If the angle of refraction exceeds 30 °, the rate of mixing of the transverse wave increases, and the sensitivity decreases. Absent.

The frequency of the ultrasonic wave used for the inspection is 4
It is preferable that the frequency is not less than 10 MHz and not more than 10 MHz. If the frequency is less than 4 MHz, the wavelength of the ultrasonic wave becomes longer, and accordingly, the directional angle becomes larger and the directivity decreases. The higher the frequency is, the shorter the wavelength of the ultrasonic wave is, the more the directivity is improved and the measurement sensitivity is improved.
If it exceeds Hz, the amount of attenuation of the ultrasonic wave inside the joined body becomes too large, and the measurement sensitivity is undesirably lowered.

Furthermore, in order for the receiving probe 8 to catch the ultrasonic wave that has entered the bonding material 1 from the transmitting probe 7 and transmitted through the bonding interface 4, the transmitting probe 7 and the receiving probe 8 It is necessary to set the relative position accurately. The ultrasonic wave incident on the bonding material 1 from the transmission vibration probe 8 propagates while repeating total reflection on the outer peripheral surface and the inner peripheral surface of the bonding material 1. It is necessary to place the ultrasonic wave totally reflected on the inner peripheral surface to reach the outer peripheral surface of the bonding material 1 or the ultrasonic wave totally reflected on the outer peripheral surface of the bonding material 1 reaches the inner peripheral surface of the bonding material 1. is there.

The ultrasonic wave incident on the bonding material 1 from the transmitting probe 7 arranged on the outer circumference of the bonding material 1 is totally reflected on the inner circumference of the bonding material 1 and reaches the outer circumference of the bonding material 1. Assuming that the horizontal distance is 1 skip, the skip position at which the receiving probe 8 is arranged may be appropriately selected according to the shape of the bonding material 1 to be inspected and the measurement conditions. In the case of FIG. 3, the receiving probe 8
Is arranged at the position of the fourth skip from the transmission probe 7.

Next, a method for measuring the attenuation of the ultrasonic wave transmitted through the bonding interface 4 of the bonding material 1 will be described. In accordance with the same procedure as the above-described flaw detection process, when ultrasonic waves are incident on the bonding material 1 from the transmission probe 7, the incident ultrasonic waves are reflected on the steel pipe 2.
While repeating total internal reflection on the inner and outer peripheral surfaces of
Propagating towards. In the process, the ultrasonic waves pass through the bonding interface 4. When a predetermined number of reflections have been performed, the receiving probe 8 placed on the steel pipe 3
The ultrasonic waves are received.

The received ultrasonic wave is converted into an electric signal by a vibrator provided on the receiving probe 8 and sent to a receiving section of an inspection device (not shown) via a high-frequency cable. Then, the attenuation amount of the ultrasonic wave is obtained from the ratio of the electric energy received by the receiving probe 8 to the electric energy input to the transmitting probe 7.

It should be noted that if the scanning between the transmitting probe 7 and the receiving probe 8 is made to move forward, backward, left and right while maintaining a constant distance (for example, a distance corresponding to four skips), the entire surface of the joint interface 4 can be scanned. The point that dimensional information can be obtained is the same as in the flaw detection process described above. In this case, the average value of the attenuation measured at each position of the bonding interface 4 may be used as the attenuation of the ultrasonic wave transmitted through the bonding interface 4.

As the scanning method, zigzag scanning,
The point that various methods such as front-back scanning, left-right scanning and the like can be used, and the scanning distance is at least a distance equivalent to 0.5 skips in the direction perpendicular to the bonding interface 4 and in the direction parallel to the bonding interface 4 Is that the scanning may be performed by a distance corresponding to the width of the bonding interface 4 or the circumference of the tube.
If two or more transmission probes 7 and two or more reception probes 8 are arranged, the operation distance is shortened, and the inspection time can be shortened in the same manner as in the above-described flaw detection process.

Further, in FIG. 3, the transmission probe 7 and the reception probe 8 are arranged one by one with the bonding interface 4 interposed therebetween, but two or more reception probes 8 are arranged. May be. When two or more receiving probes 8 are arranged, one receiving probe 8
The attenuation of the ultrasonic wave from one to the other receiving probe 8 can be measured, so that not only the attenuation of the ultrasonic wave transmitted through the bonding interface 4 but also the heat-affected zone extending right and left across the bonding interface 4 It is also possible to measure the amount of attenuation of the ultrasonic wave transmitted through.

Next, how to estimate the bonding characteristics by the ultrasonic inspection method of the bonding material according to the present invention will be described. The attenuation of the ultrasonic waves is caused by a part of the ultrasonic waves propagating in the joined body being scattered during the propagation. It is known that scattering of ultrasonic waves is caused by various causes, for example, crystal grain boundaries, internal friction, dislocation motion, phase boundaries having different acoustic impedances, and the like.

Incidentally, since the metallurgical joining method involves heating in the joining process, the heating causes diffusion of elements, phase transformation, grain growth, etc. in the material to be joined, and the properties near the joining interface change before and after joining. There are cases. In particular, when the properties near the bonding interface are sensitive to the thermal history, the properties near the bonding interface greatly change due to slight fluctuations in the bonding conditions, and the attenuation of the ultrasonic wave transmitted through the bonding interface changes significantly. Will appear.

If the properties of the joining material near the joining interface are sensitive to the thermal history, and the mechanical properties of the joining material are also sensitive to the thermal history, the joining conditions A slight change causes a large change in the mechanical properties of the bonding material. Therefore, in such a system, the change in the amount of ultrasonic attenuation and the change in the joining conditions or mechanical properties correspond one-to-one, and the joining conditions,
It is possible to estimate a change in the joining characteristics such as mechanical properties.

From the above-mentioned point, the ultrasonic inspection method for the bonding material according to the present invention can be applied to any system in which the attenuation and mechanical properties of the ultrasonic wave fluctuate due to the fluctuation of the bonding conditions. The larger the system, the higher the inspection accuracy. For example, from the viewpoint of the joining method, the diffusion joining method is particularly preferable. In the diffusion bonding method, bonding is performed at a temperature of about 90% of the melting point of a material to be bonded, and fluctuations in ultrasonic attenuation due to fluctuations in bonding conditions in order to actively diffuse elements at the bonding interface. This is because remarkably appears.

In terms of the material of the material to be joined, the iron-based materials include, for example, a duplex stainless steel having a structure in which austenite is dispersed at a ratio of 1: 1 in ferrite ground, Particularly preferred are precipitation hardening stainless steels based on. Austenitic crystal grains tend to be coarsened during the bonding process, and the scattering of ultrasonic waves at the crystal grain boundaries is large, so if the properties of austenite near the bonding interface change due to fluctuations in bonding conditions, the attenuation of ultrasonic waves will change. This is because it appears remarkably.

On the other hand, when a defect such as a crack or a pore is present at the bonding interface 4, the ultrasonic wave is reflected by the defect.
The attenuation of the ultrasonic wave transmitted through the bonding interface 4 increases. Therefore, in a system in which the larger the attenuation of the ultrasonic wave is, the better the bonding characteristics are, if the inspection process is directly performed on the bonding material 1 in which the bonding interface 4 has a defect,
A large amount of attenuation is measured, and it is erroneously determined that the bonding characteristics are good.

However, according to the present invention, the presence or absence of a defect is determined in the flaw detection process before measuring the attenuation of the ultrasonic wave in the inspection process, so that the increase in the attenuation caused by the defect is measured in the inspection process. Never. Therefore, it is possible to avoid a situation in which the joining characteristics of the joining material 1 having a defect are erroneously determined to be good. In addition, since the amount of attenuation of the ultrasonic wave is accurately measured, the accuracy of estimating the bonding characteristics is also improved.

Next, a specific procedure of the ultrasonic inspection method for a bonding material according to the present invention will be described. First, a standard joined body for examining in advance the correspondence between the joining characteristics and the attenuation of the ultrasonic wave transmitted through the joining interface is prepared. The material to be used for the production of the standard bonded body must be at least the same material as the material to be used for the actual bonding material, but the shape must be the same in order to increase the estimation accuracy of the bonding characteristics. It is desirable to do.

Next, the bonding of the standard bonded body is performed under various conditions while intentionally changing the bonding characteristics to be evaluated. For example, in the case of a joining material used for a structure on which a stress acts, the joining strength is the most important evaluation item, and the joining strength is most affected by the joining temperature. Therefore, in such a case, the bonding temperature may be selected as the bonding characteristic, and standard bonded bodies may be manufactured at various bonding temperatures around the recommended bonding temperature.

Further, for example, in the case of a system in which the strength, toughness, etc. near the bonding interface fluctuates greatly due to the heat treatment performed after the bonding, heat treatment conditions that are expected to fluctuate in the actual bonding operation, for example, heat treatment temperature, holding temperature A standard bonded body may be produced by intentionally changing the time, cooling rate, and the like.

Next, with respect to the standard bonded body thus manufactured, after confirming that there is no defect in the bonding interface 4 by using a flaw detection process as shown in FIG. 1 or another non-destructive inspection, As shown in FIG. 3, the transmission probe 7 and the reception probe 8 are arranged with the bonding interface 4 interposed therebetween, and the state where the distance between the transmission probe 7 and the reception probe 8 is kept constant is maintained. While scanning back and forth and right and left, the attenuation of the ultrasonic wave transmitted through each position of the bonding interface 4 is sequentially measured, and the average value is calculated.

When the bonding characteristics to be evaluated are the bonding conditions such as the bonding temperature, the obtained attenuation amount of the ultrasonic wave is compared with the bonding conditions, and the correlation between the two may be obtained. Normally, one of the joining conditions such as the amount of attenuation and the joining temperature is plotted on the horizontal axis and the other is plotted on the vertical axis, and the measured data is plotted to perform a regression analysis. If one changes linearly with respect to one change, simple regression may be performed, and if the other changes linearly with one change, polynomial regression may be performed.

When the bonding characteristics to be evaluated are mechanical characteristics such as tensile strength, a test piece is cut out from each of the standard bonded bodies after the ultrasonic inspection of the standard bonded bodies is completed, and a fracture such as a tensile test is performed. A test may be performed. Then, from the obtained attenuation and the data of the destructive test, a correlation between the two is obtained by regression analysis or the like according to the same procedure as described above.

Then, based on the correlation between the obtained ultrasonic attenuation of the standard joined body and the joining characteristics, a criterion for making a pass / fail judgment is created in consideration of the variation of each measurement data. The criterion may be appropriately determined in consideration of the reliability required for the bonding material, the required characteristics, the variation in the measured ultrasonic attenuation, and the like.

Next, as shown in FIG. 1, a bonding material that is actually bonded and whose bonding characteristics are unknown (hereinafter referred to as “unknown bonding material”) is transmitted to one side of the bonding interface 4 as shown in FIG. The probe 5 and the receiving probe 6 are arranged, and the intensity of the reflected wave is measured.

When the intensity of the reflected wave is at the level of the noise echo, it is determined that there is no defect in the bonding interface 4.
Next, as shown in FIG. 3, the transmitting probe 7 and the receiving probe 6 are arranged on both sides of the bonding interface, and the attenuation of the ultrasonic wave is measured under the same conditions as the standard bonded body. Then, the measured attenuation and the attenuation of the standard joint are compared, and from the correlation between the ultrasonic attenuation of the standard joint and the joining characteristics obtained by regression analysis, etc., the joining characteristics of the unknown joining material are determined. presume.

For example, when the simple regression is performed and the correlation coefficient is close to 1, the regression line of the ultrasonic attenuation for the joint characteristics substantially coincides with the regression line of the ultrasonic characteristics for the ultrasonic attenuation. Therefore, the ultrasonic attenuation measured for the unknown joining material is substituted into the regression line obtained for the standard joined body, and the joining characteristics of the unknown joining material are calculated backward. Then, if the back-calculated bonding characteristic is within a predetermined criterion, it is determined to pass, and if it is out of the criterion, it is rejected.

Alternatively, if the regression coefficient of the regression line obtained for the standard joint is sufficiently large, the section estimation of the joining characteristics at a predetermined rejection rate using the measured ultrasonic attenuation of the unknown joining material. May be performed, and if the estimated joining characteristics are within the predetermined criteria, it may be judged as pass, and if not, the test may be rejected. The rejection rate is
What is necessary is just to select suitably according to the reliability required of a joining material.

Then, the unknown joining material actually joined is
When joined according to the operation manual, the properties of the joining interface of the unknown joining material can be almost the same as the joining interface of the standard joint that satisfies the required joining characteristics Therefore, there is a high possibility that the measured attenuation amount of the ultrasonic wave falls within the above-described criterion.

On the other hand, when the joining operation is not performed according to the operation manual due to the force majeure and the joining conditions are fluctuating, the joining characteristics are changed. Outside values will be detected and a reject decision will be made. In addition, for the unknown joining material that was determined to be defective in the flaw detection process and for the unknown joining material that was determined to be rejected in the inspection process, measures such as cutting off the joint and rejoining as necessary Will be taken.

(Example 1) An example in which the ultrasonic inspection method for a joining material according to the present invention is applied to a joining material obtained by joining a duplex stainless steel pipe as a material to be joined by a liquid phase diffusion joining method. Will be described.

First, a standard joined body was prepared according to the following procedure. That is, the material to be joined is a duplex stainless steel S
US329J1 outer diameter 150mm, inner diameter 120m
m, and the joint interface has a surface roughness of Rmax30.
It was finished to be less than μm. Also, a Ni-based alloy foil having a melting point of 1040 ° C. and a thickness of 40 μm was used as the insert material.

An insert material is inserted between the two duplex stainless steel tubes, a pressure of 4 MPa is applied to the joint interface, and the temperature is maintained at 1150 ° C. to 1300 ° C. for 60 seconds in an Ar gas atmosphere. And liquid phase diffusion bonding of a duplex stainless steel tube.

As shown in FIG. 1, a transmitting probe 5 and a receiving probe 6 are arranged on one side of the bonding interface 4 with respect to the obtained bonding material. Was measured for strength. Note that a transverse wave was used for measuring the reflected wave.

Next, for all of the produced bonding materials,
As shown in FIG. 3, the transmission probe 7 and the reception probe 8 were arranged with the joint interface 4 interposed therebetween, and the attenuation (relative relative ultrasonic intensity) of the ultrasonic wave transmitted through the joint interface 4 was measured. The transmitting probe 7 and the receiving probe 8 are 10 mm square transducers made of lead zircon titanate, and the attenuation is measured by measuring a longitudinal wave having a frequency of 5 MHz using a refraction angle of 20 mm. This was performed by making the light incident on the joining material in ゜. In addition, the transmission probe 7
And the distance between the receiving probe 8 and the receiving probe 8 was 4 skips.

FIGS. 4 and 5 show the relationship between the obtained attenuation amount (relative ratio ultrasonic intensity) of the ultrasonic wave transmitted through the bonding interface 4 and the bonding temperature. FIG. 4 shows the relationship between the relative specific ultrasonic intensity and the joining temperature obtained only for the joining material whose intensity of the reflected wave was determined to be the noise echo level in the flaw detection process, and FIG. The relationship between the relative ultrasonic strength and the bonding temperature obtained for all the bonding materials obtained is shown.

When the correlation with the joining temperature was obtained using the relative ratio ultrasonic intensity measured for all the produced joining materials, a regression line (shown by a solid line in FIG. 5) was obtained as shown in FIG. The measurement data is scattered around ()), and it can be seen that a weak correlation is observed between the relative specific ultrasonic intensity and the bonding temperature. In the case of FIG. 5, the correlation coefficient between the ultrasonic relative specific strength and the bonding temperature was -0.66.

On the other hand, when the correlation with the joining temperature is obtained by using the relative ratio ultrasonic intensity measured only for the joining material whose intensity of the reflected wave is determined to be the noise echo level in the flaw detection process, As shown in FIG. 4, the measurement data is concentrated near the regression line (indicated by the solid line in FIG. 4), and it can be seen that a strong correlation is observed between the relative specific ultrasonic intensity and the bonding temperature. In the case of FIG. 4, the correlation coefficient between the relative intensity of the ultrasonic waves and the bonding temperature was -0.92.

Next, a tensile test piece (JIS Z 3124 No. 4 test piece) was cut out from all the obtained joining materials.
A tensile test was performed at a crosshead speed of 1 mm / min. FIGS. 6 and 7 show the relationship between the obtained attenuation amount (relative ratio ultrasonic intensity) of the ultrasonic wave transmitted through the bonding interface 4 and the bonding temperature.

FIG. 6 shows the relationship between the relative specific ultrasonic intensity and the tensile strength obtained only for the bonding material whose intensity of the reflected wave was determined to be the noise echo level in the flaw detection process. Shows the relationship between the relative strength ultrasonic strength and the tensile strength obtained for all of the manufactured joining materials.

When the correlation with the tensile strength was obtained using the relative ratio ultrasonic intensity measured for all the produced bonding materials, a regression line (shown by a solid line in FIG. 7) was obtained as shown in FIG. The measurement data is scattered around ()), and it can be seen that a weak correlation is observed between the relative specific ultrasonic intensity and the tensile strength. In the case of FIG. 7, the correlation coefficient between the ultrasonic relative specific strength and the tensile strength was -0.53.

On the other hand, when the correlation with the tensile strength was obtained using the relative ratio ultrasonic intensity measured only for the bonding material whose intensity of the reflected wave was determined to be the noise echo level in the flaw detection process, As shown in FIG. 6, the measurement data is concentrated near the regression line (indicated by a solid line in FIG. 6), and it can be seen that a strong correlation is observed between the relative specific ultrasonic intensity and the tensile strength. In the case of FIG. 6, the correlation coefficient between the ultrasonic relative specific strength and the tensile strength was improved to -0.91.

In the flaw detection step, an unbonded portion was observed in each of the fractured surfaces of the tensile test pieces cut out from the bonding material whose intensity of the reflected wave exceeded the noise echo level. Therefore, the decrease in the correlation coefficient in FIG. 5 and FIG. 7 is considered to be due to the fact that the ultrasonic wave was reflected by the unjoined portion, and the data in which the attenuation increased more than usual was included.

Next, a test was conducted to confirm whether or not the joining characteristics of joining materials having different joining characteristics could be actually estimated based on the results obtained with the standard joined body. First, simple regression was performed on the experimental data obtained in FIGS. 4 and 6, and the following regression equation was obtained. Ultrasonic relative specific strength = −0.083 × (joining temperature) +91 (1) Tensile strength = −40 × (ultrasonic relative specific strength) +150 (2)

Next, according to the same procedure as that of the above-mentioned standard bonded body, ten bonding materials having a bonding temperature of 1300 ° C. and ten bonding materials having a bonding temperature of 1150 ° C. were produced.
Next, the strength of the ultrasonic wave reflected from the bonding interface 4 is measured in a state where the history of each bonding material is turned down, and the bonding material whose reflected wave intensity is the noise echo level and the reflected wave intensity is the noise echo level It classified into more than joining materials.

Next, only the joining material judged to have the intensity of the ultrasonic wave reflected from the joining interface 4 at the noise echo level was measured by using a rectangular probe having a side of 10 mm and a longitudinal wave having a frequency of 5 MHz. At an angle of refraction of 20 ° to measure the attenuation of the ultrasonic wave transmitted through the bonding interface 4,
The joining temperature of the joining material was estimated. The criterion is
Based on the regression equation of (1), the relative intensity of the ultrasonic wave is −10 d.
B or more (corresponding to a joining temperature of 1200 ° C. or less) was rejected. As a result, it was possible to detect and sort all the joining materials having the joining temperature of 1300 ° C.

The tensile strength calculated back from the measured ultrasonic attenuation using the regression equation (2) was 826 MPa for a joining material with a joining temperature of 1300 ° C., and the joining temperature was 1150 ° C. It was 328 MPa for the bonding material. On the other hand, the selected steel pipe joined at 1300 ° C. and 115
A test piece was actually cut out from each of the steel pipes joined at 0 ° C., and the tensile strength was measured.
Pa and 360 MPa were in good agreement with the results estimated from the regression equation of (2).

From the above results, it was found that by measuring the attenuation of the ultrasonic wave transmitted through the bonding interface, the bonding characteristics such as bonding temperature and bonding strength can be estimated. In addition, it was found that if defects were detected by a flaw detection process before measuring the attenuation of the ultrasonic wave transmitted through the bonding interface, the bonding characteristics could be estimated with high accuracy.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention. .

For example, in the above embodiment, after performing the flaw detection step of measuring the intensity of the ultrasonic wave reflected from the bonding interface,
Performs an inspection process to measure the attenuation of ultrasonic waves transmitted through the bonding interface, but to measure the transmission and reception probes for measuring the intensity of reflected waves, and to measure the attenuation of transmitted waves The transmission probe and the reception probe may be arranged on the bonding material at predetermined intervals, and the measurement of the intensity of the reflected wave and the measurement of the attenuation of the transmitted wave may be performed simultaneously.

Thus, the intensity of the reflected wave and the attenuation of the transmitted wave can be simultaneously measured in one scan, so that the intensity of the reflected wave and the attenuation of the transmitted wave can be measured separately.
The scanning time can be halved.

Further, in the above embodiment, the present invention is applied to the joining material of steel pipes. However, the present invention can be applied not only to the steel pipe but also to a plate-like joining material. In the above embodiment, the present invention is applied to a joining material obtained by joining a duplex stainless steel by a liquid phase diffusion joining method using a Ni-based alloy as an insert material. The present invention can be applied to a joining material joined by a joining method, a fusion welding method, a pressure welding method, or the like, and the same effects as those of the above embodiment can be obtained.

Further, the material to be joined is not limited to the duplex stainless steel or the precipitation hardening stainless steel based on the duplex stainless steel, but the ultrasonic attenuation greatly varies depending on the variation of the joining conditions and the like. The present invention can be applied to any joining material as long as the joining material is a material having properties.

For example, since pearlite has a layered structure of ferrite and cementite, the attenuation of ultrasonic waves increases, but the attenuation of ultrasonic waves tends to decrease in martensite or an intermediate structure. Therefore, when joining steel materials containing pearlite and rapidly cooling the joint to generate martensite, or when joining steel materials containing martensite or an intermediate structure and gradually cooling the joint to produce pearlite In this case, it is possible to detect the change in the amount of attenuation of the ultrasonic wave transmitted through the bonding interface, and it is possible to estimate the bonding characteristics from the amount of ultrasonic attenuation.

[0092]

As described above, according to the present invention, the correlation between the attenuation of the ultrasonic wave transmitted through the bonding interface of the standard bonded body bonded under known conditions and the bonding characteristics is determined in advance, and the measured bond bonded under unknown conditions is determined. Since the joining characteristics of the material are estimated from the attenuation of the ultrasonic wave transmitted through the interface of the material to be measured, the joining characteristics such as joining temperature and joining strength can be estimated nondestructively. There is.

Before measuring the amount of attenuation of the ultrasonic wave, the presence or absence of a defect at the joint interface is determined by measuring the intensity of the reflected wave reflected from the joint interface. This has the effect of improving the accuracy of measuring the amount of attenuation of the ultrasonic wave, thereby improving the accuracy of estimating the bonding characteristics.

Further, by simultaneously measuring the intensity of the ultrasonic wave reflected from the bonding interface and the attenuation of the ultrasonic wave transmitted through the bonding interface, the inspection time can be reduced and the efficiency of the bonding operation can be improved. There is an effect that can be.

As described above, according to the ultrasonic inspection method of the bonding material according to the present invention, the bonding characteristics such as the bonding temperature and the bonding strength can be estimated with high accuracy even if the bonding material cannot be sampled. Therefore, if this is applied to, for example, inspection of oil well pipes and pipes of chemical plants, it is possible to increase the reliability of the joining process. is there.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a flaw detection step of an ultrasonic inspection method according to the present invention.

FIG. 2 is a cross-sectional view of a probe used in the ultrasonic inspection method according to the present invention.

FIG. 3 is a schematic configuration diagram showing an inspection process of the ultrasonic inspection method according to the present invention.

FIG. 4 is a diagram showing the relationship between the relative ultrasonic strength of the bonding material subjected to the flaw detection step and the bonding temperature.

FIG. 5 is a diagram showing a relationship between a relative specific ultrasonic intensity of a bonding material that has not undergone a flaw detection step and a bonding temperature.

FIG. 6 is a diagram showing the relationship between the relative specific ultrasonic strength and the tensile strength of a bonding material that has undergone a flaw detection process.

FIG. 7 is a diagram showing the relationship between the relative specific ultrasonic strength and the tensile strength of a bonding material that has not undergone a flaw detection step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Joining material 2, 3 Steel pipe 4 Joining interface 5, 7 Transmission probe 6, 8 Receiving probe

Claims (6)

[Claims] 1 or 2 on one side of a bonding interface of a bonding material.
The above-described angle beam probe is arranged, ultrasonic waves are incident from the angle beam probe toward the bonding interface of the bonding material, and the intensity of the reflected wave reflected from the bonding interface is measured. A flaw detection step of judging whether or not a defect exists at the bonding interface based on the intensity of the wave; and one side of the bonding interface of the bonding material determined to have no defect at the bonding interface by the flaw detection step. Is a transmission angle beam probe, and the other side is a reception angle beam probe, and the ultrasonic wave transmitted from the transmission angle beam is transmitted through the bonding interface. Then, the amount of attenuation of the ultrasonic wave when the ultrasonic wave is received by the receiving angle beam probe is measured, and based on the measured value, the supersonic wave of the standard bonded body that is bonded under known bonding conditions measured in advance is measured. An inspection step of inspecting the bonding characteristics of the bonding material from the correlation between the sound attenuation and the bonding characteristics. Ultrasonic inspection method of the bonding material, characterized by that example. 2. The ultrasonic inspection method for a bonding material according to claim 1, wherein the bonding characteristic is a bonding temperature. 3. The ultrasonic inspection method for a bonding material according to claim 1, wherein the bonding characteristic is bonding strength. 4. The ultrasonic wave according to claim 1, wherein the determination of the presence or absence of a defect by the flaw detection step and the estimation of the bonding characteristics by the inspection step are performed on the bonding material at the same time. Inspection methods. 5. The ultrasonic inspection method for a bonding material according to claim 4, wherein the bonding characteristic is a bonding temperature. 6. The ultrasonic inspection method for a bonding material according to claim 4, wherein the bonding characteristic is bonding strength.