Method for evaluating cross-sectional shape of welded portion, device for evaluating cross-sectional shape of welded portion, and method for welding metallic materials

Abstract

A method and apparatus for evaluating the cross-sectional shape of a weld that can evaluate the cross-sectional shape of a weld metal nondestructively and with high accuracy. [Solution] The device for evaluating the cross-sectional shape of a weld according to the present invention comprises a transmitter / receiver unit that focuses ultrasonic waves near the weld via a coupling medium, transmits ultrasonic waves at multiple refraction angles via the coupling medium at angles inclined relative 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; a signal processor that amplifies and filters the reflected waves for each of the multiple refraction angles, and then uses the reflected waves after amplification and filtering to extract echo heights within a detection gate for each of the multiple refraction angles, generates an image showing the distribution of echo heights within the detection gate for each refraction angle of the ultrasonic waves, and generates an echo height map by combining 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 weld, an apparatus for evaluating the cross-sectional shape of a weld, and a method for welding metallic materials. [Background technology]

[0002] It is known that the cross-sectional shape of weld metal in welded joints of metallic materials affects the mechanical performance of the weld. For example, Patent Document 1 describes that the cross-sectional shape of weld metal in welded joints of steel pipes affects the toughness of the weld. For this reason, from the perspective of quality control and quality assurance of welded joints, techniques have been proposed for imaging the cross-sectional shape of weld metal and non-destructively evaluating it. For example, Patent Documents 2 and 3 describe techniques for imaging the cross-sectional shape of weld metal by receiving ultrasonic waves reflected at the boundary between the base material and the weld. Specifically, the techniques described in Patent Documents 2 and 3 receive reflected waves of ultrasonic waves transmitted obliquely to the boundary between the base material and the weld while moving a probe or switching the transducers of an array probe. The techniques described in Patent Documents 2 and 3 then identify the reflection points of the ultrasonic waves from the received reflected waves to image the cross-sectional shape of the weld metal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-233679 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-069077 [Patent Document 3] International Publication No. 2014 / 013940 Summary of the Invention [Problem 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 identify the cross-sectional shape of the weld metal based on reflected waves of an intensity equal to or greater than a threshold detected within the detection gate. For this reason, the techniques described in Patent Documents 2 and 3 may misidentify the cross-sectional shape of the weld metal or fail to identify the cross-sectional shape of the weld metal by identifying the cross-sectional shape of the weld metal based on reflected waves of an intensity greater than the intensity of the ultrasonic waves reflected at the boundary.

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

[0006] The method for evaluating the cross-sectional shape of a weld according to the present invention is a method for evaluating the cross-sectional shape of a weld metal in a weld of metallic materials, and includes an ultrasonic array control step of focusing ultrasonic waves near the weld through a couplant; an ultrasonic transmission step of transmitting ultrasonic waves at a plurality of refraction angles through the couplant at angles inclined with respect to a thickness direction of the metallic material; an ultrasonic reception step of receiving reflected waves of the ultrasonic waves through the couplant for each of the plurality of refraction angles of the ultrasonic waves; an echo height extraction step of amplifying and filtering the reflected waves for each of the plurality of refraction angles, and then extracting echo heights within a detection gate for each of the plurality of refraction angles using the reflected waves after the amplified and filtered processes; and generating an image showing the distribution of echo heights within the detection gate for each of the plurality of refraction angles, the ultrasonic wave excitation voltage in the ultrasonic wave transmission step is within the range of 20 to 150 V, the refraction angle interval in the ultrasonic wave transmission step is 5 degrees or less when the distance between the probe that transmits and receives ultrasonic waves and the welded portion is set so that 0 skip or more and 0.5 skip or less of ultrasonic waves coincides with the boundary between the base metal and the welded metal, or 3 degrees or less when the distance between the probe and the welded portion is set so that 0.5 skip or more and 1.0 skip or less of ultrasonic waves coincides with the boundary between the base metal and the welded metal, and the amplification gain of the reflected wave in the echo height extraction step is within 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 apparatus for evaluating the cross-sectional shape of a weld according to the present invention is an apparatus for evaluating the cross-sectional shape of a weld metal in a weld of a metallic material, and includes a transmitter / receiver that focuses ultrasonic waves near the weld through a couplant, transmits the ultrasonic waves at a plurality of refraction angles through the couplant at angles inclined with respect to the thickness direction of the metallic material, and receives reflected waves of the ultrasonic waves through the couplant for each of the plurality of refraction angles of the ultrasonic waves; amplifies and filters the reflected waves for each of the plurality of refraction angles, and then uses the reflected waves after the amplified and filtered processes to extract echo heights within a detection gate for each of the plurality of refraction angles, and generates an image showing the distribution of echo heights within the detection gate for each of the refraction angles of the ultrasonic waves; The apparatus comprises a signal processing unit that generates an echo height map by combining the images at corresponding refraction angles, and an output unit that outputs the echo height map, wherein the transmission / reception unit sets the excitation voltage of the ultrasonic waves within a range of 20 to 150 V, and when the transmission / reception unit sets the distance between the probe that transmits and receives the ultrasonic waves and the welded part so that a skip of 0 to 0.5 of the ultrasonic waves coincides with the boundary between the base metal and the weld metal, the transmission / reception unit sets the interval of the refraction angles to 5 degrees or less, and when the distance between the probe that transmits and receives the ultrasonic waves and the welded part is set so that a skip of more than 0.5 to 1.0 of the ultrasonic waves coincides with the boundary between the base metal and the welded metal, the interval of the refraction angles to 3 degrees or less, and the signal processing unit sets the amplification gain of the reflected wave within a range of 30 to 60 dB.

[0009] The welding method for metallic materials according to the present invention includes a step of adjusting welding conditions for the weld based on the evaluation results 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] The method and apparatus for evaluating the cross-sectional shape of a weld according to the present invention enable the cross-sectional shape of a weld metal to be evaluated non-destructively and with high accuracy. Also, the method for welding metallic materials according to the present invention enables the creation of a weld having desired mechanical properties. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing the configuration of an evaluation device for the cross-sectional shape of a welded portion according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of the transmitting and receiving unit shown in FIG. [Figure 3] FIG. 3 is a flowchart showing the flow of the evaluation process according to one embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing an example of an image showing echo heights and the distribution of echo heights. [Figure 5] FIG. 5 is a diagram showing an example of an echo height map. [Figure 6] FIG. 6 is a diagram showing an echo height map of an example of the invention. [Figure 7] FIG. 7 is a diagram showing an echo height map of an example of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the configuration and operation of an evaluation device for the cross-sectional shape of a welded portion according to one embodiment of the present invention will be described with reference to the drawings.

[0013] 〔composition〕 First, the configuration of an evaluation device for the cross-sectional shape of a welded portion according to one embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a block diagram showing the configuration of an evaluation device for the cross-sectional shape of a welded portion according to one embodiment of the present invention. Figure 2 is a schematic diagram showing the configuration of a transmitter / receiver 1a shown in Figure 1.

[0014] As shown in Figure 1, an embodiment of the present invention, an evaluation device for the cross-sectional shape of a weld (hereinafter referred to as the evaluation device) 1, transmits ultrasonic waves at multiple refraction angles to a weld of a metallic material, and generates and outputs an echo height map by synthesizing images showing the distribution of echo heights within a detection gate at angles corresponding to the refraction angles of the ultrasonic waves. Using this echo height map, a user can accurately and nondestructively evaluate the cross-sectional shape of the weld metal by checking on the map lines of the same echo height that extend in the direction of penetration of the weld metal from the boundary between the base metal surface and the reinforcement. Details of the echo height map will be described later.

[0015] The evaluation device 1 includes a transceiver 1a, a controller 1b, a signal processor 1c, and an output unit 1d. As shown in FIG. 2, the transceiver 1a includes an array probe 11 with multiple transducers and a wedge 12, and operates in accordance with a control signal from the controller 1b. Specifically, the transceiver 1a drives the array probe 11 in accordance with the control signal from the controller 1b, thereby focusing shear wave mode ultrasonic waves near the weld W of the metal material S via the wedge 12 and the couplant 13. Examples of the couplant 13 include glycerin paste, a glycerin aqueous solution with a concentration of 75% (volume fraction) or more, water, oil, etc.

[0016] Moreover, the transmitter / receiver 1a drives the array probe 11 in accordance with a control signal from the controller 1b, thereby transmitting ultrasonic waves at multiple refraction angles at angles inclined with respect to the thickness direction of the metal material S via the wedge 12 and the couplant 13. Furthermore, the transmitter / receiver 1a drives the array probe 11 in accordance with a control signal from the controller 1b, thereby receiving some or all of the reflected waves of the ultrasonic waves transmitted at multiple refraction angles via the couplant 13 and the wedge 12, and outputs electrical signals indicating the received reflected waves to the signal processor 1c for each of the multiple refraction angles.

[0017] Returning to FIG. 1, the control unit 1b is configured with 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 ultrasonic excitation voltage to 20 V or more, preferably 40 V or more, so that the boundary between the base metal and the weld metal M (see FIG. 2) can be clearly identified in the echo height map described above. On the other hand, if the ultrasonic excitation voltage is excessively large, noise will be generated, adversely affecting the identification of the boundary between the base metal and the weld metal M, so the control unit 1b controls the ultrasonic excitation voltage to 150 V or less, preferably 100 V or less, and more preferably 80 V.

[0018] The control unit 1b also focuses the ultrasonic waves at a position in front of the wedge 12 in the propagation direction A of the transmitted ultrasonic waves (see FIG. 2). However, to clearly identify the boundary between the base metal and the weld metal M in the echo height map, it is preferable to set the ultrasonic wave focusing position to a position 10 mm or more away from the installation position of the array probe 11 in the direction of the probe-to-weld distance (Y distance). Furthermore, if the refraction angle of the ultrasonic waves is less than 30 degrees, the ultrasonic waves become longitudinal wave mode and cannot be used. Furthermore, if the refraction angle of the ultrasonic waves exceeds 80 degrees, surface waves are generated and the ultrasonic waves cannot be used. For this reason, it is preferable that the control unit 1b include a range of 30 to 80 degrees as the range of the refraction angle of the ultrasonic waves.

[0019] Furthermore, if the interval between the refraction angles of the ultrasonic waves is increased, the resolution of the echo height map decreases, making it 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 W is set so that the ultrasonic waves from 0 skip to 0.5 skip coincide with the boundary between the base metal and the weld metal, the control unit 1b sets the refraction angles of the ultrasonic waves at intervals of 5 degrees or less, preferably 3 degrees or less. When the distance D between the array probe 11 and the weld W is set so that the ultrasonic waves from 0.5 skip to 1.0 skip coincide with the boundary between the base metal and the weld metal, the control unit 1b sets the refraction angles of the ultrasonic waves at intervals of 3 degrees or less, preferably 2 degrees or less.

[0020] The signal processing unit 1c is configured with an information processing device such as a computer, and uses the electrical signals representing the reflected waves input from the transmitting / receiving unit 1a to generate an echo height map for evaluating the cross-sectional shape of the weld metal M at the weld W of the metallic material S. Specifically, the signal processing unit 1c amplifies and filters the electrical signals representing the reflected waves input from the transmitting / receiving unit 1a, and then extracts an image representing the distribution of echo heights within the detection gate for each ultrasonic refraction angle. The signal processing unit 1c then generates an echo height map by combining the images for each ultrasonic refraction angle at the position of the corresponding ultrasonic refraction angle, and outputs the generated echo height map to the output unit 1d.

[0021] In order to clearly identify the boundary between the base metal 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 excessively large, noise will be generated, adversely affecting the identification of the boundary between the base metal and the weld metal M, so the signal processing unit 1c sets the amplification gain of the reflected wave to 60 dB or less. Furthermore, frequency components of the reflected wave less than 2 MHz contain only noise, and do not include signals from the boundary between the base metal and the weld metal M. For this reason, it is preferable that the signal processing unit 1c removes frequency components of the reflected wave less than 2 MHz in filter processing and uses only frequency components of the reflected wave equal to or greater than 2 MHz.

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

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

[0024] 3 is a flowchart showing the flow of the evaluation process according to one embodiment of the present invention. The flowchart shown in FIG. 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 the process of step S1, the control unit 1b controls the transmitting and receiving unit 1a to drive the array probe 11 and focus ultrasonic waves in shear wave mode near the weld W via the wedge 12 and the contact medium 13 (ultrasonic array control step). This completes the process of step S1, and the evaluation process proceeds to the process of step S2.

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

[0027] In the process of step S3, the control unit 1b controls the transmitting / receiving unit 1a to drive the array probe 11 and receive some or all of the reflected ultrasonic waves for each refraction angle of the ultrasonic waves via the contact medium 13 and the wedge 12 (ultrasound receiving step). Then, the control unit 1b controls the transmitting / receiving unit 1a to output an electrical signal indicating the received reflected waves for each refraction angle of the ultrasonic waves to the signal processing unit 1c. This completes the process of step S3, and the evaluation process proceeds to the process of step S4.

[0028] In the process of step S4, first, the signal processing unit 1c performs amplification and filtering on the reflected waves for each refraction angle of the ultrasonic waves. Then, as shown in Fig. 4(a), the signal processing unit 1c uses the reflected waves after amplification and filtering to extract the echo height within the detection gate for each refraction angle of the transmitted ultrasonic waves (echo height extraction step). Note that Fig. 4(a) shows the echo height within the detection gate at a certain refraction angle. This completes the process of step S4, and the evaluation process proceeds to the process of step S5.

[0029] In the processing of step S5, first, the signal processing unit 1c generates an image showing the distribution of echo heights within the detection gate for each refraction angle of the transmitted ultrasound, as shown in FIG. 4(b). The format of the image showing the echo height distribution is not limited as long as it allows differences in echo height to be identified, and examples include RGB format and grayscale format. Then, as shown in FIG. 5, the signal processing unit 1c generates an echo height map as shown in FIG. 5 by combining the images for each refraction angle of the ultrasound at the position of the corresponding refraction angle of the ultrasound (echo height imaging step). The image surrounded by the rectangular area shown in FIG. 5 corresponds to the image shown in FIG. 4(b), and the angle θ shown in FIG. 5 corresponds to the refraction angle of the ultrasound at which the echo height shown in FIG. 4(a) was obtained. Then, the output unit 1d outputs the generated echo height map. This completes the processing of step S5, and the series of evaluation processes ends.

[0030] Thereafter, 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 the location of the weld defect or abnormality in the penetration shape and investigate the cause of the abnormality. Furthermore, by checking the cross-sectional shape of the weld metal immediately after welding, the user can adjust the welding conditions to improve the cross-sectional shape of the weld metal and manage mechanical performance, such as weld toughness, which is affected by the cross-sectional shape of the weld metal. For example, the user can adjust the welding conditions by increasing the welding current if the penetration depth is insufficient, or by decreasing the welding speed or increasing the arc voltage if undercut occurs. This allows the creation of a weld with the desired mechanical performance.

[0031] [Example] In this example, the preferred ranges of the excitation voltage, amplification gain, refraction angle, and refraction angle interval were evaluated for the welded portion of a UOE steel pipe with an outer diameter of 36 inches and a thickness of 38.1 mm. The echo height map changes with changes in the ultrasonic skip number, excitation voltage, focal position, filter frequency, amplification gain, and refraction angle interval. Glycerin paste was used as the couplant. Furthermore, the bead widths of the inner and outer weld metals were measured at the longitudinal center of the weld bead. When the bead width values ​​calculated from the echo height map obtained in this test were within ±2 mm of the measured bead width values ​​for both the inner and outer weld metals, the results were evaluated as "Good." When at least one of the inner and outer weld metals exceeded ±2 mm, the results were evaluated as "Poor." The evaluation results are shown in Table 1. The echo height maps obtained for Examples No. 21 and No. 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 a series of lines (dotted lines in the figure) of the same density originating at the boundary between the steel surface on the inner side of the steel pipe and the weld on the inner side of the steel pipe, represented by a series of intermittent lines of constant density along the horizontal axis around 40 mm on the vertical axis. In the echo height map shown in Figure 7, the cross-sectional shape of the weld could be clearly identified by a series of lines (dotted lines in the figure) of the same density originating at the boundary between the inner side of the steel pipe and the weld metal and between the outer side of the steel pipe and the molten metal, in the direction of weld metal penetration, between the steel surface on the inner side of the steel pipe, represented by a series of intermittent lines of constant density along the horizontal axis around 40 mm on the vertical axis, and the steel surface on the outer side of the steel pipe, represented by a series of intermittent lines of constant density along the horizontal axis around 80 mm on the vertical axis.

[0033] Nos. 1 to 14, 21, and 22 in Table 1 are inventive examples, and good results were obtained. On the other hand, Nos. 15 to 20 are comparative examples that do not satisfy the conditions of the present invention, and the bead width values ​​calculated from the echo height maps obtained in this test were more than ±2 mm different from the bead width values ​​actually measured on at least one of the inner and outer weld metals. This confirms that the cross-sectional shape of weld metal can be evaluated nondestructively and with high accuracy according to the present invention.

[0034] [Table 1]

[0035] The above describes an embodiment of the invention made by the present inventor, but the present invention is not limited to the description and drawings that form part of the disclosure of the present invention according to this embodiment. For example, in the above example, a UOE steel pipe in which the internal and external welding are each performed using one-pass submerged arc welding was described. However, the subject of evaluation of the present invention is not limited to this example and can be applied to any metallic material to which welding is applied. In other words, other embodiments, examples, operational techniques, etc. made by those skilled in the art based on this embodiment are all included in the scope of the present invention. [Explanation of symbols]

[0036] 1. Evaluation device for the cross-sectional shape of welded parts 1a Transmitter / Receiver 1b Control section 1c Signal processing section 1d Output section 11 Array Probe 12 Wedges 13 Couplant A. Direction of ultrasonic wave D distance M weld metal S Metal material W welded section

Claims

1. A method for evaluating a cross-sectional shape of a welded portion of a metallic material, comprising: an ultrasonic array control step of focusing ultrasonic waves through a couplant near the weld; an ultrasonic wave transmitting step of transmitting the ultrasonic waves at a plurality of refraction angles through the contact medium at angles inclined with respect to the thickness direction of the metal material; an ultrasonic wave receiving step of receiving reflected waves of the ultrasonic waves via the contact medium at each of a plurality of refraction angles of the ultrasonic waves; an echo height extraction step of amplifying and filtering the reflected waves for each of the plurality of refraction angles, and then extracting an echo height within a detection gate for each of the plurality of refraction angles using the reflected waves after the amplification and filtering; an echo height imaging step of generating an image showing a distribution of echo heights within the detection gate for each of the plurality of refraction angles, generating an echo height map by combining the images at the corresponding refraction angles, and outputting the generated echo height map; evaluating a cross-sectional shape of the weld metal based on the echo height map; Including, the ultrasonic excitation voltage in the ultrasonic transmission step is in the range of 20 to 150 V; The intervals of the refraction angles in the ultrasonic wave transmission step are 5 degrees or less when the distance between the probe that transmits and receives ultrasonic waves and the welded portion is set so that an ultrasonic wave of 0 skip or more and 0.5 skip or less coincides with the boundary between the base metal and the weld metal, and are 3 degrees or less when the distance between the probe and the welded portion is set so that an ultrasonic wave of 0.5 skip or more and 1.0 skip or less coincides with the boundary between the base metal and the welded metal, the amplification gain of the reflected wave in the echo height extraction step is within a range of 30 to 60 dB; A method for evaluating the cross-sectional shape of a weld.

2. The method for evaluating the cross-sectional shape of a weld according to claim 1 , wherein the echo height extraction step includes a step of removing frequency components of the reflected wave that are less than 2 MHz.

3. An evaluation device for evaluating a cross-sectional shape of a weld metal in a weld of a metallic material, comprising: a transmitting / receiving unit that focuses ultrasonic waves near the weld through a couplant, transmits the ultrasonic waves at multiple refraction angles at angles inclined with respect to the thickness direction of the metal material through the couplant, and receives reflected waves of the ultrasonic waves at each of the multiple refraction angles through the couplant; a signal processing unit that performs amplification and filtering on the reflected waves for each of the plurality of refraction angles, and then extracts echo heights within a detection gate for each of the plurality of refraction angles using the reflected waves after the amplification and filtering, generates an image showing a distribution of echo heights within the detection gate for each refraction angle of the ultrasonic waves, and generates an echo height map by combining the images for the corresponding refraction angles; an output unit that outputs the echo height map; Equipped with the transmitting and receiving unit sets an excitation voltage of the ultrasonic waves within a range of 20 to 150 V, and when the distance between the probe that transmits and receives the ultrasonic waves and the welded portion is set so that a skip of 0 or more and a skip of 0.5 or less of the ultrasonic waves coincides with the boundary between the base metal and the weld metal, the intervals of the refraction angles are 5 degrees or less, and when the distance between the probe that transmits and receives the ultrasonic waves and the welded portion is set so that a skip of more than 0.5 and a skip of 1.0 or less of the ultrasonic waves coincides with the boundary between the base metal and the weld metal, the intervals of the refraction angles are 3 degrees or less; the signal processing unit sets the amplification gain of the reflected wave within a range of 30 to 60 dB; A device for evaluating the cross-sectional shape of welds.

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

Images