Method for evaluating the cross-sectional shape of a welded joint, apparatus for evaluating the cross-sectional shape of a welded joint, and welding method for metal materials.

Abstract

To provide a method and apparatus for evaluating the cross-sectional shape of a welded joint that can non-destructively and accurately evaluate the cross-sectional shape of the welded metal. [Solution] The apparatus for evaluating the cross-sectional shape of a welded joint according to the present invention comprises: a transmitting and receiving unit that focuses ultrasonic waves near the welded joint via a coupling medium, transmits ultrasonic waves of multiple refraction angles via the coupling medium at an angle inclined with respect to the thickness direction of the metal material, and receives reflected ultrasonic waves via the coupling medium for each of the multiple refraction angles of the ultrasonic waves; a signal processing unit that performs amplification and filtering on the reflected waves for each of the multiple refraction angles, extracts the echo height within the detection gate for each of the multiple refraction angles using the amplified and filtered reflected waves, generates an image showing the distribution of echo height within the detection gate for each of the ultrasonic refraction angles, and generates an echo height map by synthesizing the images at the corresponding refraction angles; and an output unit that outputs the echo height map.

Description

Technical Field

[0001] The present invention relates to a method for evaluating the cross-sectional shape of a welded portion, an apparatus for evaluating the cross-sectional shape of a welded portion, and a method for welding a metal material.

Background Art

[0002] [[ID=||]] It is known that the cross-sectional shape of the weld metal in the welded portion of a metal material affects the mechanical properties of the welded portion. For example, Patent Document 1 describes that the cross-sectional shape of the weld metal in the welded portion of a steel pipe affects the toughness of the welded portion. Therefore, from the viewpoints of quality control and quality assurance of the welded portion, techniques for imaging and non-destructively evaluating the cross-sectional shape of the weld metal have been proposed. For example, Patent Documents 2 and 3 describe techniques for imaging the cross-sectional shape of the weld metal by receiving ultrasonic waves reflected at the boundary between the base metal portion and the welded portion. Specifically, the techniques described in Patent Documents 2 and 3 receive the reflected waves of ultrasonic waves obliquely transmitted to the boundary between the base metal portion and the welded portion while moving the probe or switching the vibrators of the array probe. Then, the techniques described in Patent Documents 2 and 3 image the cross-sectional shape of the weld metal by specifying the reflection points of the ultrasonic waves from the received reflected waves.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] The techniques described in Patent Documents 2 and 3 set a time range for detecting reflected waves as a detection gate, and determine the cross-sectional shape of the weld metal based on reflected waves with an intensity greater than or equal to a threshold detected within the detection gate. Therefore, according to the techniques described in Patent Documents 2 and 3, the cross-sectional shape of the weld metal may be misidentified or may not be determined at all because the cross-sectional shape of the weld metal is determined based on reflected waves with an intensity stronger than the intensity of the ultrasonic waves reflected at the boundary.

[0005] The present invention has been made to solve the above problems, and its objective is to provide a method and apparatus for evaluating the cross-sectional shape of a welded joint that can evaluate the cross-sectional shape of the weld metal nondestructively and accurately. Another objective of the present invention is to provide a welding method for metal materials that can produce a welded joint having desired mechanical performance. [Means for solving the problem]

[0006] The present invention provides a method for evaluating the cross-sectional shape of a welded joint, which is a method for evaluating the cross-sectional shape of a weld metal in a welded joint of a metal material, comprising: an ultrasonic array control step of focusing ultrasonic waves near the welded joint via a coupling medium; an ultrasonic transmission step of transmitting ultrasonic waves at multiple refraction angles via the coupling medium at an angle inclined with respect to the thickness direction of the metal material; an ultrasonic reception step of receiving reflected waves of the ultrasonic waves via the coupling medium for each of the multiple refraction angles of the ultrasonic waves; an echo height extraction step of performing amplification and filtering on the reflected waves for each of the multiple refraction angles, and then using the reflected waves after amplification and filtering to extract the echo height within a detection gate for each of the multiple refraction angles; and generating an image showing the distribution of echo height within the detection gate for each of the multiple refraction angles. The ultrasonic wave extraction step includes an echo height imaging step of generating an echo height map by synthesizing the images at corresponding refraction angles and outputting the generated echo height map, and a step of evaluating the cross-sectional shape of the weld metal based on the echo height map, wherein the excitation voltage of the ultrasonic wave in the ultrasonic wave transmission step is in the range of 20 to 150 V, the interval of the refraction angle in the ultrasonic wave transmission step is 5 degrees or less when the distance between the transducer that transmits and receives ultrasonic waves and the weld is set so that 0 to 0.5 skips of ultrasonic waves coincide with the boundary between the base material and the weld metal, or 3 degrees or less when the distance between the transducer and the weld is set so that 0 to 1.0 skips of ultrasonic waves coincide with the boundary between the base material and the weld metal, and the amplification gain of the reflected wave in the echo height extraction step is in the range of 30 to 60 dB.

[0007] The echo height extraction step may include a step of removing frequency components of the reflected wave below 2 MHz.

[0008] The present invention provides a device for evaluating the cross-sectional shape of a welded joint, which evaluates the cross-sectional shape of the weld metal in a welded joint of a metal material, comprising: a transmitting and receiving unit that focuses ultrasonic waves near the welded joint via a coupling medium, transmits ultrasonic waves at multiple refraction angles via the coupling medium at an angle inclined with respect to the thickness direction of the metal material, and receives reflected waves of the ultrasonic waves via the coupling medium for each of the multiple refraction angles of the ultrasonic waves; and after applying amplification and filtering processing to the reflected waves for each of the multiple refraction angles, extracts the echo height within a detection gate for each of the multiple refraction angles using the reflected waves after amplification and filtering, generates an image showing the distribution of echo height within the detection gate for each of the refraction angles of the ultrasonic waves, and The transmitting and receiving unit comprises a signal processing unit that generates an echo height map by synthesizing the recorded images at corresponding refraction angles, and an output unit that outputs the echo height map, wherein the transmitting and receiving unit sets the excitation voltage of the ultrasonic waves within the range of 20 to 150 V, and sets the refraction angle interval to 5 degrees or less when the distance between the transducer that transmits and receives ultrasonic waves and the weld is set so that the ultrasonic wave skip of 0 to 0.5 coincides with the boundary between the base material and the weld metal, and sets the refraction angle interval to 3 degrees or less when the distance between the transducer that transmits and receives ultrasonic waves and the weld is set so that the ultrasonic wave skip of more than 0.5 to 1.0 coincides with the boundary between the base material and the weld metal, and sets the refraction angle interval to 3 degrees or less, and the amplification gain of the reflected waves within the range of 30 to 60 dB.

[0009] The welding method for metal materials according to the present invention includes the step of adjusting the welding conditions of the weld based on the evaluation result of the cross-sectional shape of the weld metal using the evaluation method for the cross-sectional shape of the weld according to the present invention. [Effects of the Invention]

[0010] According to the method and apparatus for evaluating the cross-sectional shape of a welded joint of the present invention, the cross-sectional shape of the weld metal can be evaluated non-destructively and accurately. Furthermore, according to the welding method for metal materials of the present invention, a welded joint having desired mechanical properties can be produced. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a block diagram showing the configuration of an evaluation device for the cross-sectional shape of a welded joint, which is one embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram showing the configuration of the transmitting and receiving unit shown in Figure 1. [Figure 3] Figure 3 is a flowchart showing the evaluation process flow in one embodiment of the present invention. [Figure 4] Figure 4 shows an example of an image illustrating echo height and its distribution. [Figure 5] Figure 5 shows an example of an echo height map. [Figure 6] Figure 6 shows an echo height map of an example of the invention. [Figure 7] Figure 7 shows the echo height map of the example invention. [Modes for carrying out the invention]

[0012] The configuration and operation of an evaluation device for the cross-sectional shape of a welded joint, which is one embodiment of the present invention, will be described below with reference to the drawings.

[0013] 〔composition〕 First, with reference to Figures 1 and 2, the configuration of a device for evaluating the cross-sectional shape of a welded joint, which is one embodiment of the present invention, will be described. Figure 1 is a block diagram showing the configuration of a device for evaluating the cross-sectional shape of a welded joint, which is one embodiment of the present invention. Figure 2 is a schematic diagram showing the configuration of the transmitting and receiving unit 1a shown in Figure 1.

[0014] As shown in Figure 1, the weld cross-sectional shape evaluation device (hereinafter abbreviated as "evaluation device") 1, which is one embodiment of the present invention, transmits ultrasonic waves to the weld of a metal material at multiple refraction angles and generates and outputs an echo height map by synthesizing images showing the distribution of echo heights within the detection gate at angles corresponding to the refraction angles of the ultrasonic waves. According to this echo height map, the user can accurately and non-destructively evaluate the cross-sectional shape of the weld metal by confirming on the map lines of the same echo height extending in the penetration direction of the weld metal, starting from the boundary between the base material surface and the weld bead. Details of the echo height map will be described later.

[0015] The evaluation device 1 includes a transmission / reception unit 1a, a control unit 1b, a signal processing unit 1c, and an output unit 1d. As shown in FIG. 2, the transmission / reception unit 1a includes an array probe 11 having a plurality of vibrators and a wedge 12, and operates according to a control signal from the control unit 1b. Specifically, the transmission / reception unit 1a focuses ultrasonic waves in a shear wave mode near the welded portion W of the metal material S through the wedge 12 and the coupling medium 13 by driving the array probe 11 according to a control signal from the control unit 1b. Examples of the coupling medium 13 include glycerin paste, an aqueous glycerin solution with a concentration of 75% (volume fraction) or more, water, oil, and the like.

[0016] Also, the transmission / reception unit 1a transmits ultrasonic waves with a plurality of refraction angles at an angle inclined with respect to the thickness direction of the metal material S through the wedge 12 and the coupling medium 13 by driving the array probe 11 according to a control signal from the control unit 1b. Further, the transmission / reception unit 1a receives part or all of the reflected waves of the ultrasonic waves transmitted at a plurality of refraction angles through the coupling medium 13 and the wedge 12 by driving the array probe 11 according to a control signal from the control unit 1b, and outputs an electrical signal indicating the received reflected waves to the signal processing unit 1c for each of the plurality of refraction angles.

[0017] Returning to FIG. 1, the control unit 1b is constituted by an information processing device such as a computer and controls the operation of the transmission / reception unit 1a. Specifically, the control unit 1b controls the excitation voltage of the ultrasonic waves to be 20 V or more, preferably 40 V or more, so that the boundary between the base material and the weld metal M (see FIG. 2) can be clearly identified in the above-described echo height map. On the other hand, if the excitation voltage of the ultrasonic waves is made excessively large, noise will occur and it will have an adverse effect on the identification of the boundary between the base material and the weld metal M. Therefore, the control unit 1b controls the excitation voltage of the ultrasonic waves to be 150 V or less, preferably 100 V or less, more preferably 80 V.

[0018] Further, the control unit 1b focuses the ultrasonic wave at a position in front of the wedge 12 in the traveling direction A of the transmitted ultrasonic wave (see FIG. 2). However, in order to clearly identify the boundary between the base material and the weld metal M in the echo height map, it is preferable that the focusing position of the ultrasonic wave be at a position more than 10 mm away from the installation position of the array probe 11 in the direction of the probe welding part distance (Y distance). Further, when the refraction angle of the ultrasonic wave is less than 30 degrees, the ultrasonic wave becomes a longitudinal wave mode and cannot be used. Further, when the refraction angle of the ultrasonic wave exceeds 80 degrees, a surface wave is generated and it cannot be used. Therefore, it is preferable that the control unit 1b includes a range of 30 to 80 degrees as the range of the refraction angle of the ultrasonic wave.

[0019] Further, when the interval of the refraction angle of the ultrasonic wave is increased, the resolution of the echo height map decreases, and it becomes difficult to identify the cross-sectional shape of the weld metal. Therefore, when the distance D (see FIG. 2) between the array probe 11 and the weld part W is set so that 0 skip or more and 0.5 skip or less of the ultrasonic wave coincides with the boundary between the base material and the weld metal, the control unit 1b sets the refraction angle of the ultrasonic wave to 5 degrees or less, preferably 3 degrees or less. Further, when the distance D between the array probe 11 and the weld part W is set so that more than 0.5 skip and 1.0 skip or less of the ultrasonic wave coincides with the boundary between the base material and the weld metal, the control unit 1b sets the refraction angle of the ultrasonic wave to 3 degrees or less, preferably 2 degrees or less.

[0020] The signal processing unit 1c is constituted by an information processing device such as a computer, and generates an echo height map for evaluating the cross-sectional shape of the weld metal M in the weld part W of the metal material S by using an electric signal indicating the reflected wave input from the transmission / reception unit 1a. Specifically, the signal processing unit 1c amplifies and filters the electric signal indicating the reflected wave input from the transmission / reception unit 1a, and then extracts an image indicating the distribution of the echo height in the detection gate for each refraction angle of the ultrasonic wave. Then, the signal processing unit 1c generates an echo height map by synthesizing the images for each refraction angle of the ultrasonic wave at the position of the corresponding refraction angle of the ultrasonic wave, and outputs the generated echo height map to the output unit 1d.

[0021] Furthermore, in order to clearly distinguish the boundary between the base material and the weld metal M in the echo height map, the signal processing unit 1c sets the amplification gain of the reflected wave to 30 dB or more, preferably 40 dB or more. On the other hand, if the amplification gain is made excessively large, noise will be generated, which will adversely affect the identification of the boundary between the base material and the weld metal M, so the signal processing unit 1c sets the amplification gain of the reflected wave to 60 dB or less. In addition, the frequency components of the reflected wave below 2 MHz consist only of noise and do not contain signals from the boundary between the base material and the weld metal M. For this reason, the signal processing unit 1c should remove the frequency components of the reflected wave below 2 MHz in the filtering process and use only the frequency components of the reflected wave above 2 MHz.

[0022] The output unit 1d consists of a display device such as a liquid crystal display, a printing device such as a printer, a communication device, etc., and outputs a map of the echo height output from the signal processing unit 1c.

[0023] [Evaluation process] Next, with reference to Figures 3 to 5, a method for evaluating the cross-sectional shape of a welded joint using the evaluation device 1 will be described.

[0024] Figure 3 is a flowchart showing the flow of an evaluation process according to one embodiment of the present invention. The flowchart shown in Figure 3 starts when an execution command for the evaluation process is input to the evaluation device 1, and the evaluation process proceeds to step S1.

[0025] In step S1, the control unit 1b controls the transmitting / receiving unit 1a to drive the array probe 11 and focus the transverse wave mode ultrasonic waves near the weld W via the wedge 12 and coupling medium 13 (ultrasonic array control step). This completes step S1, and the evaluation process proceeds to step S2.

[0026] In step S2, the control unit 1b controls the transmitting / receiving unit 1a to drive the array transducer 11 and transmit ultrasonic waves with multiple refraction angles at angles inclined with respect to the thickness direction of the metal material S via the wedge 12 and coupling medium 13 (ultrasonic transmission step). This completes step S2, and the evaluation process proceeds to step S3.

[0027] In step S3, the control unit 1b drives the array transducer 11 by controlling the transmitting / receiving unit 1a, and receives part or all of the ultrasonic reflected waves via the coupling medium 13 and wedge 12 at each ultrasonic refraction angle (ultrasonic reception step). Then, the control unit 1b outputs an electrical signal indicating the received reflected wave to the signal processing unit 1c at each ultrasonic refraction angle by controlling the transmitting / receiving unit 1a. With this, the process of step S3 is completed, and the evaluation process proceeds to step S4.

[0028] In step S4, the signal processing unit 1c first performs amplification and filtering on the reflected waves for each refraction angle of the ultrasound. Then, as shown in Figure 4(a), the signal processing unit 1c uses the amplified and filtered reflected waves to extract the echo height within the detection gate for each refraction angle of the transmitted ultrasound (echo height extraction step). Figure 4(a) shows the echo height within the detection gate at a certain refraction angle. With this, the processing of step S4 is completed, and the evaluation process proceeds to step S5.

[0029] In step S5, the signal processing unit 1c first generates an image showing the distribution of echo heights within the detection gate for each refraction angle of the transmitted ultrasound, as shown in Figure 4(b). The format of the image showing the distribution of echo heights is not limited as long as it can distinguish the differences in echo heights, and examples include RGB format and grayscale format. Then, as shown in Figure 5, the signal processing unit 1c generates an echo height map as shown in Figure 5 by combining the images for each ultrasound refraction angle at the corresponding ultrasound refraction angle position (echo height imaging step). The image enclosed by the rectangular region shown in Figure 5 corresponds to the image shown in Figure 4(b), and the angle θ shown in Figure 5 corresponds to the refraction angle of the ultrasound from which the echo height shown in Figure 4(a) was obtained. The output unit 1d then outputs the generated echo height map. With this, the processing of step S5 is completed, and the series of evaluation processes is finished.

[0030] Subsequently, the user evaluates the cross-sectional shape of the weld metal by referring to the echo height map. Specifically, the user refers to the echo height map to identify where welding defects or abnormalities in penetration shape occur and investigate the cause of the abnormalities. In addition, by checking the cross-sectional shape of the weld metal immediately after welding, the user adjusts the welding conditions to improve the cross-sectional shape of the weld metal and manages mechanical performance such as weld toughness, which is affected by the cross-sectional shape of the weld metal. For example, if the penetration depth is insufficient, the welding current is increased; if undercut occurs, the welding speed is reduced or the arc voltage is increased, etc., to adjust the welding conditions. This makes it possible to produce a weld with the desired mechanical performance.

[0031] [Examples] In this example, the optimal ranges for excitation voltage, amplification gain, refraction angle, and refraction angle interval in the present invention were evaluated by assessing the changes in the echo height map associated with changes in the ultrasonic skip number, excitation voltage, focusing position, filter frequency, amplification gain, and refraction angle interval, using a welded joint of a UOE steel pipe with an outer diameter of 36 inches and a thickness of 38.1 mm. Glycerin paste was used as the coupling medium. Furthermore, the bead width of the inner and outer weld metals was measured at the longitudinal center of the weld bead. A good result was evaluated as "○" when the bead width value obtained from the echo height map obtained in this test was within ±2 mm of the measured bead width value for both the inner and outer weld metals, and an unsatisfactory result was evaluated as "×" when at least one of the inner and outer weld metals exceeded ±2 mm. The evaluation results are shown in Table 1. The echo height maps obtained for the invention examples No. 21 and 22 are shown in Figures 6 and 7, respectively.

[0032] In the echo height map shown in Figure 6, the cross-sectional shape of the weld could be clearly identified by lines (dotted lines in the figure) that started from the boundary between the inner surface of the steel pipe and the weld on the inner surface of the steel pipe, represented by intermittent lines of constant density horizontally connected around 40 mm on the vertical axis, and the boundary between the outer surface of the steel pipe and the molten metal, and started from the boundary (dotted lines in the figure) that started from the boundary between the inner surface of the steel pipe and the weld metal, and the boundary between the outer surface of the steel pipe and the molten metal, and started from the boundary (dotted lines in the figure) that started from the boundary between the inner surface of the steel pipe and the weld metal, and the boundary between the outer surface of the steel pipe and the molten metal, between the inner surface of the steel pipe and the outer surface of the steel pipe, represented by intermittent lines of constant density horizontally connected around 40 mm on the vertical axis and the outer surface of the steel pipe, and the outer surface of the steel pipe.

[0033] Table 1 shows examples of the invention, Nos. 1-14, 21, and 22, which yielded favorable results. On the other hand, Nos. 15-20 are comparative examples that do not meet the conditions of the present invention, and the bead width value obtained from the echo height map obtained in this test exceeded ±2 mm from the measured bead width value in at least one of the inner weld metal and the outer weld metal. This confirms that, according to the present invention, the cross-sectional shape of the weld metal can be evaluated non-destructively and accurately.

[0034] [Table 1]

[0035] Although embodiments applying the invention made by the present inventors have been described above, the present invention is not limited by the descriptions and drawings that constitute part of the disclosure of the present invention in these embodiments. For example, in the above embodiments, the case of a UOE steel pipe to which submerged arc welding with one pass each for internal and external welding was applied was described, but the scope of evaluation of the present invention is not limited to these embodiments and can be applied to all metal materials to which welding is applied. In other words, other embodiments, examples, and operational techniques made by those skilled in the art based on these embodiments are all included in the scope of the present invention. [Explanation of Symbols]

[0036] 1. Apparatus for evaluating the cross-sectional shape of a welded joint. 1a Transceiver Unit 1b Control Unit 1c Signal Processing Unit 1d Output section 11 Array probe 12 Wedge 13. Coupling catalyst A Direction of ultrasound propagation D Distance M Weld metal S Metal material W Weld

Claims

1. A method for evaluating the cross-sectional shape of a welded joint in a metal material, which evaluates the cross-sectional shape of the weld metal in the welded joint, An ultrasonic array control step that focuses ultrasonic waves onto the vicinity of the weld area via a coupling catalyst, An ultrasonic transmission step of transmitting ultrasonic waves with multiple refraction angles through the coupling medium at an angle inclined with respect to the thickness direction of the metal material, An ultrasonic receiving step of receiving the reflected ultrasonic waves through the coupling medium at each of the multiple refraction angles of the ultrasonic waves, After applying amplification and filtering to the reflected waves for each of the plurality of refraction angles, an echo height extraction step is performed to extract the echo height within the detection gate for each of the plurality of refraction angles using the reflected waves after amplification and filtering. The echo height imaging step involves generating an image showing the distribution of echo height within the detection gate for each of the multiple refraction angles, generating an echo height map by combining the images at the corresponding refraction angles, and outputting the generated echo height map. A step of evaluating the cross-sectional shape of the weld metal based on the echo height map, Includes, The excitation voltage of the ultrasonic wave in the ultrasonic wave transmission step is within the range of 20 to 150 V. The interval of the refraction angle in the ultrasonic transmission step is 5 degrees or less if the distance between the ultrasonic transducer and the weld is set so that 0 to 0.5 skips of the ultrasonic waves coincide with the boundary between the base material and the weld metal, and if the distance between the transducer and the weld is set so that 0 to 1.0 skips of the ultrasonic waves coincide with the boundary between the base material and the weld metal. The amplification gain of the reflected wave in the echo height extraction step is in the range of 30 to 60 dB. A method for evaluating the cross-sectional shape of a welded joint.

2. The method for evaluating the cross-sectional shape of a welded joint according to claim 1, wherein the echo height extraction step includes a step of removing frequency components of the reflected wave below 2 MHz.

3. A device for evaluating the cross-sectional shape of a welded joint, which evaluates the cross-sectional shape of the weld metal in a welded joint of a metal material, A transmitting and receiving unit that focuses ultrasonic waves near the weld area via a coupling medium, transmits ultrasonic waves with multiple refraction angles via the coupling medium at angles inclined with respect to the thickness direction of the metal material, and receives the reflected waves of the ultrasonic waves via the coupling medium for each of the multiple refraction angles of the ultrasonic waves, A signal processing unit that, after amplifying and filtering the reflected waves for each of the plurality of refraction angles, extracts the echo height within the detection gate for each of the plurality of refraction angles using the amplified and filtered reflected waves, generates an image showing the distribution of echo height within the detection gate for each of the ultrasonic refraction angles, and generates an echo height map by synthesizing the images at the corresponding refraction angles, The output unit outputs the aforementioned echo height map, Equipped with, The transmitting and receiving unit sets the excitation voltage of the ultrasonic waves within the range of 20 to 150 V, and the transmitting and receiving unit sets the distance between the transducer that transmits and receives ultrasonic waves and the weld so that the ultrasonic wave skip of 0 to 0.5 skips coincides with the boundary between the base material and the weld metal, and sets the refraction angle interval to 5 degrees or less, and sets the distance between the transducer that transmits and receives ultrasonic waves and the weld so that the ultrasonic wave skip of more than 0.5 skips and 1.0 skips coincides with the boundary between the base material and the weld metal, and sets the refraction angle interval to 3 degrees or less. The signal processing unit sets the amplification gain of the reflected wave to a range of 30 to 60 dB. A device for evaluating the cross-sectional shape of welded joints.

4. A method for welding metal materials, comprising the step of adjusting the welding conditions of a weld based on the evaluation result of the cross-sectional shape of the weld metal using the method for evaluating the cross-sectional shape of a weld described in claim 1 or 2.

Images