Ultrasonic detection method applied to large austenitic stainless steel forgings

Abstract

The invention provides an ultrasonic detection method applied to a large austenitic stainless steel forge piece, which comprises the following steps of: dividing a forge piece to be detected into a central area, an outer layer and a near surface layer from inside to outside according to a detection sonic path distance; carrying out ultrasonic detection on a plurality of reference reflectors with different depths by adopting an ultrasonic detector and based on a single crystal normal probe, and carrying out ultrasonic detection on an outer layer by taking an obtained first DAC curve as reference sensitivity; performing ultrasonic detection on the central area by adopting a noise method; and performing ultrasonic detection on a reference reflector containing different depths by adopting an ultrasonic detector based on the bicrystal normal probe, and performing ultrasonic detection on a near surface layer by taking an obtained second DAC curve as reference sensitivity. According to the invention, the ultrasonic detection of the large austenitic stainless steel forgings can be realized by using a conventional ultrasonic detector.

Description

Technical Field

[0001] The invention belongs to the technical field of ultrasonic detection, and more specifically, relates to an ultrasonic detection method applied to large austenitic stainless steel forgings. Background Art

[0002] At present, ultrasonic testing of large austenitic stainless steel forgings cannot be achieved based on conventional ultrasonic testing instruments. The material of large austenitic stainless steel forgings is austenitic stainless steel, one of the main characteristics of which is relatively coarse grains. This characteristic will cause severe ultrasonic scattering attenuation. The scattered ultrasonic waves propagate to the probe along a complex path, forming a grass-like echo, resulting in a decrease in the signal-to-noise ratio, which may lead to two situations: one is that the noise signal is higher than the defect echo, resulting in the inability to detect defects; the other is that the grain echo signal is misjudged as a defect signal. If a conventional ultrasonic testing instrument is used to perform ultrasonic testing on large austenitic stainless steel forgings, when the detection depth is less than 300mm, the signal-to-noise ratio of the echo signal is sufficient to achieve normal detection, and when the detection depth is in the range of 300mm to 600mm, the signal-to-noise ratio of the echo signal gradually decreases, even less than 6dB, and the complex geometry of the workpiece cannot obtain effective bottom echo reflection of the parallel surface, so conventional ultrasonic testing is difficult to implement. Summary of the invention

[0003] The purpose of the present invention is to realize ultrasonic testing of large austenitic stainless steel forgings by using a conventional ultrasonic testing instrument.

[0004] In order to achieve the above object, the present invention provides an ultrasonic detection method for large austenitic stainless steel forgings, the method comprising the following steps:

[0005] According to the detection sound range, the forging to be tested is divided into the central area, the outer layer and the near-surface layer from the inside to the outside;

[0006] Using an ultrasonic detector and a single crystal straight probe to perform ultrasonic testing on a plurality of reference reflectors at different depths, and using the obtained first DAC curve as a reference sensitivity to perform ultrasonic testing on the outer layer;

[0007] Performing ultrasonic testing on the central area using a noise method;

[0008] An ultrasonic detector is used to perform ultrasonic testing on a reference reflector having different depths based on a dual-crystal straight probe, and the obtained second DAC curve is used as a reference sensitivity to perform ultrasonic testing on the near-surface layer.

[0009] Optionally, the detection sound range corresponding to the central area is greater than 300 mm, the detection sound range corresponding to the outer layer is greater than 45 mm to 300 mm, and the detection sound range of the near-surface layer is 0 to 45 mm.

[0010] Optionally, the sound path of the reference reflectors with the largest sound path among the multiple reference reflectors at different depths used to obtain the first DAC curve is at least 300 mm;

[0011] The maximum sound path of a block of reference reflectors of different depths used to obtain the second DAC curve is at least 45 mm.

[0012] Optionally, using the obtained first DAC curve as a reference sensitivity to perform ultrasonic testing on the outer layer includes:

[0013] Taking the first DAC curve as a reference sensitivity, setting the scanning sensitivity to be 6 dB higher than the reference sensitivity;

[0014] An ultrasonic detector is used to perform ultrasonic testing on the outer layer based on a single crystal straight probe, all echo signals with a level greater than the first DAC curve are recorded, and the recorded echo signals are evaluated with reference to the reference sensitivity.

[0015] Optionally, the adopting a noise method to perform ultrasonic detection on the central area includes:

[0016] Place the single crystal straight probe on the forging to be tested, adjust the detection sound path of the ultrasonic detector, and adjust the gain of the ultrasonic detector so that the body noise of the forging to be tested reaches 20% of the full screen height of the instrument;

[0017] The body noise reaching 20% ​​of the full screen height of the instrument is taken as the reference sensitivity, and the scanning sensitivity is set to be the same as the reference sensitivity;

[0018] An ultrasonic detector is used to perform ultrasonic testing on the central area based on a single crystal straight probe, and echo signals reaching 40% of the full screen height of the instrument are recorded and not accepted.

[0019] Optionally, the step of using the obtained second DAC curve as a reference sensitivity to perform ultrasonic detection on the near-surface layer includes:

[0020] Using the second DAC curve as a reference sensitivity, setting the scanning sensitivity to be 6 dB higher than the reference sensitivity;

[0021] An ultrasonic detector is used to perform ultrasonic testing on the near-surface layer based on a dual-crystal straight probe, all echo signals with a level greater than the second DAC curve are recorded, and the recorded echo signals are evaluated with reference to the reference sensitivity.

[0022] The beneficial effects of the present invention are:

[0023] The ultrasonic detection method for large austenitic stainless steel forgings of the present invention comprises the following steps: first, dividing the forging to be tested into a central area, an outer layer and a near-surface layer from the inside to the outside according to the detection sound path; secondly, using an ultrasonic detector and a single-crystal straight probe to perform ultrasonic detection on a plurality of reference reflectors of different depths, and using the obtained first DAC curve as a reference sensitivity to perform ultrasonic detection on the outer layer; thirdly, using a noise method to perform ultrasonic detection on the central area; finally, using an ultrasonic detector and a dual-crystal straight probe to perform ultrasonic detection on a reference reflector of different depths, and using the obtained second DAC curve as a reference sensitivity to perform ultrasonic detection on the near-surface layer.

[0024] The present invention utilizes a conventional ultrasonic detector, such as a type A pulse reflection ultrasonic detector, and a corresponding reference reflector to realize ultrasonic detection of large austenitic stainless steel forgings, effectively solving the problem in the prior art that ultrasonic detection of large austenitic stainless steel forgings cannot be realized based on a conventional ultrasonic detector.

[0025] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which the same or similar reference numerals are used throughout the drawings to represent the same or similar components.

[0027] Figure 1 A flowchart of an ultrasonic testing method for large austenitic stainless steel forgings according to an embodiment of the present invention is shown;

[0028] Figure 2 A schematic structural diagram of a large austenitic stainless steel forging according to an embodiment of the present invention is shown;

[0029] Figure 3 A schematic diagram of the division of inspection areas for a large austenitic stainless steel forging according to an embodiment of the present invention is shown;

[0030] Figure 4 A schematic diagram showing the structure of a plurality of reference reflectors at different depths according to an embodiment of the present invention is shown;

[0031] Figure 5 A schematic diagram showing a first DAC curve according to an embodiment of the present invention;

[0032] Figure 6 A schematic diagram showing a principle of acquiring a first DAC curve based on a plurality of reference reflectors at different depths according to an embodiment of the present invention;

[0033] Figure 7 It shows a schematic diagram of instrument adjustment when ultrasonic testing of a central area is performed using a noise method according to an embodiment of the present invention;

[0034] Figure 8 A schematic diagram showing the principle of obtaining a second DAC curve based on a reference reflector having different depths according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to more fully understand the technical solution of the present invention, the exemplary embodiments of the present invention will be described in more comprehensive and detailed in conjunction with the accompanying drawings below. Obviously, the one or more embodiments of the present invention described below are only one or more of the specific ways in which the technical solution of the present invention can be implemented, and are not exhaustive. It should be understood that other ways belonging to a general inventive concept can be used to implement the technical solution of the present invention, and should not be limited by the exemplary embodiments described. Based on one or more embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work should fall within the scope of protection of the present invention.

[0036] Example: Figure 1 The following is a flowchart showing the implementation of the ultrasonic testing method for large austenitic stainless steel forgings according to an embodiment of the present invention. Figure 1 The ultrasonic detection method for large austenitic stainless steel forgings according to the embodiment of the present invention comprises the following steps:

[0037] Step S100, dividing the forging to be tested into a central area, an outer layer and a near-surface layer from the inside to the outside according to the detection sound path;

[0038] Step S200, using an ultrasonic detector and a single crystal straight probe to perform ultrasonic testing on a plurality of reference reflectors at different depths, and using the obtained first DAC curve as a reference sensitivity to perform ultrasonic testing on the outer layer;

[0039] Step S300, using a noise method to perform ultrasonic testing on the central area;

[0040] Step S400: using an ultrasonic detector and a dual crystal straight probe to perform ultrasonic testing on a reference reflector having different depths, and using the obtained second DAC curve as a reference sensitivity to perform ultrasonic testing on a near-surface layer.

[0041] Further, Figure 2 The schematic diagram of the structure of a large austenitic stainless steel forging according to an embodiment of the present invention is shown. Figure 3 The schematic diagram of the inspection area division of a large austenitic stainless steel forging according to an embodiment of the present invention is shown. Figure 2 and Figure 3 In the embodiment of the present invention, the step S100 is to divide the forging to be tested into a central area, an outer layer and a near-surface layer from the inside to the outside according to the detection sound path, specifically:

[0042] According to the geometric size and shape of the forging to be tested, the forging to be tested is divided into three testing areas according to the testing sound path, namely the central area, the outer layer and the near-surface layer;

[0043] Among them, the detection sound range corresponding to the outer layer is greater than 45mm to 300mm;

[0044] The detection sound range corresponding to the central area is greater than 300mm;

[0045] The near-surface layer is a supplementary detection layer for the outer layer, and the corresponding detection sound range is 0 to 45 mm.

[0046] Further, Figure 4 A schematic diagram showing the structure of multiple reference reflectors at different depths according to an embodiment of the present invention is shown. Figure 5 FIG. 4 is a schematic diagram showing a first DAC curve according to an embodiment of the present invention, Figure 6 A schematic diagram showing the principle of acquiring a first DAC curve based on a plurality of reference reflectors at different depths according to an embodiment of the present invention.

[0047] Reference Figure 4-Figure 6 In an embodiment of the present invention, among a plurality of reference reflectors at different depths, the reference reflector having the largest sound path has a sound path of at least 300 mm.

[0048] The specific process of ultrasonic testing of the outer layer is:

[0049] An ultrasonic detector is used to perform ultrasonic testing on a plurality of reference reflectors at different depths based on a single crystal straight probe to obtain a first DAC curve, and then the detection sensitivity of the ultrasonic testing operation of the outer layer is adjusted based on the first DAC curve, that is, the first DAC curve is used as a reference sensitivity, and the scanning sensitivity is set to be 6 dB higher than the reference sensitivity;

[0050] After the above operations, an ultrasonic tester is used to perform ultrasonic testing on the outer layer based on a single crystal straight probe, all echo signals with a level greater than the first DAC curve are recorded, and the recorded echo signals are evaluated with reference to the reference sensitivity.

[0051] Further, Figure 7 The schematic diagram of the instrument adjustment when the noise method is used to perform ultrasonic testing on the central area according to the embodiment of the present invention is shown. Figure 7 In the embodiment of the present invention, the specific process of using the noise method to perform ultrasonic detection on the central area is as follows:

[0052] Place the single crystal straight probe on the forging to be tested, adjust the detection sound range of the ultrasonic detector to an appropriate range, and adjust the gain of the ultrasonic detector so that the body noise of the forging to be tested reaches 20% of the full screen height of the instrument;

[0053] Set the body noise that reaches 20% of the full screen height of the instrument as the reference sensitivity, and set the scanning sensitivity to be the same as the reference sensitivity;

[0054] An ultrasonic detector is used to perform ultrasonic testing on the central area based on a single-crystal straight probe. The echo signal that reaches 40% of the full screen height of the instrument is recorded and not accepted.

[0055] Further, Figure 8 The schematic diagram of the principle of obtaining a second DAC curve based on a reference reflector with different depths according to an embodiment of the present invention is shown. Figure 8 In the embodiment of the present invention, the specific process of ultrasonic testing of the near-surface layer is as follows:

[0056] Using an ultrasonic detector and a dual-crystal straight probe to perform ultrasonic testing on a reference reflector having different depths to obtain a second DAC curve, wherein a maximum sound path of the reference reflector having different depths is at least 45 mm;

[0057] Use the second DAC curve as the reference sensitivity and set the scanning sensitivity to 6dB higher than the reference sensitivity;

[0058] An ultrasonic detector is used to perform ultrasonic testing on the near-surface layer based on a dual-crystal straight probe, all echo signals with a level greater than the second DAC curve are recorded, and the recorded echo signals are evaluated with reference to the reference sensitivity.

[0059] Specifically, in an embodiment of the present invention, before formally performing ultrasonic testing on the outer layer of the forging to be tested, a single crystal straight probe is used to obtain a distance amplitude curve (DAC curve) using a series of reference reflectors of different depths to adjust the detection sensitivity of the ultrasonic testing operation on the outer layer; before formally performing ultrasonic testing on the central area of ​​the forging to be tested, the noise signal of the forging body to be tested is used to adjust the detection sensitivity of the ultrasonic testing operation on the central area; before formally performing ultrasonic testing on the near-surface layer, a dual crystal straight probe is used to obtain a distance amplitude curve (DAC curve) using a reference reflector of different depths to adjust the detection sensitivity of the ultrasonic testing operation on the near-surface layer.

[0060] The ultrasonic detection method applied to large austenitic stainless steel forgings of the embodiment of the present invention can easily realize ultrasonic detection operations of large austenitic stainless steel forgings, especially large austenitic stainless steel forgings with complex geometric shapes, by utilizing existing production resources, and can ensure product quality requirements.

[0061] Although one or more embodiments of the present invention are described above, it should be known to those skilled in the art that the present invention can be implemented in any other form without departing from its subject matter and scope. Therefore, the embodiments described above are illustrative rather than restrictive, and many modifications and substitutions are obvious to those skilled in the art without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. An ultrasonic testing method for large austenitic stainless steel forgings, characterized in that: include: According to the detection sound range, the forging to be tested is divided into the central area, the outer layer and the near-surface layer from the inside to the outside; Using an ultrasonic detector and a single crystal straight probe to perform ultrasonic testing on a plurality of reference reflectors at different depths, and using the obtained first DAC curve as a reference sensitivity to perform ultrasonic testing on the outer layer; Performing ultrasonic testing on the central area using a noise method; An ultrasonic detector is used to perform ultrasonic testing on a reference reflector having different depths based on a dual-crystal straight probe, and the obtained second DAC curve is used as a reference sensitivity to perform ultrasonic testing on the near-surface layer.

2. The ultrasonic testing method for large austenitic stainless steel forgings according to claim 1, characterized in that: The detection sound range corresponding to the central area is greater than 300 mm, the detection sound range corresponding to the outer layer is greater than 45 mm to 300 mm, and the detection sound range of the near-surface layer is 0 to 45 mm.

3. The ultrasonic testing method for large austenitic stainless steel forgings according to claim 2, characterized in that: The sound path of the reference reflectors with the largest sound path among the multiple reference reflectors at different depths used to obtain the first DAC curve is at least 300 mm; The maximum sound path of a block of reference reflectors of different depths used to obtain the second DAC curve is at least 45 mm.

4. The ultrasonic testing method for large austenitic stainless steel forgings according to claim 3 is characterized in that: The using the obtained first DAC curve as a reference sensitivity to perform ultrasonic testing on the outer layer comprises: Taking the first DAC curve as a reference sensitivity, setting the scanning sensitivity to be 6 dB higher than the reference sensitivity; An ultrasonic detector is used to perform ultrasonic testing on the outer layer based on a single crystal straight probe, all echo signals with a level greater than the first DAC curve are recorded, and the recorded echo signals are evaluated with reference to the reference sensitivity.

5. The ultrasonic testing method for large austenitic stainless steel forgings according to claim 4, characterized in that: The ultrasonic detection of the central area by using the noise method comprises: Place the single crystal straight probe on the forging to be tested, adjust the detection sound path of the ultrasonic detector, and adjust the gain of the ultrasonic detector so that the body noise of the forging to be tested reaches 20% of the full screen height of the instrument; The body noise reaching 20% ​​of the full screen height of the instrument is taken as the reference sensitivity, and the scanning sensitivity is set to be the same as the reference sensitivity; An ultrasonic detector is used to perform ultrasonic testing on the central area based on a single crystal straight probe, and echo signals reaching 40% of the full screen height of the instrument are recorded and not accepted.

6. The ultrasonic testing method for large austenitic stainless steel forgings according to claim 5, characterized in that: The method of using the obtained second DAC curve as a reference sensitivity to perform ultrasonic detection on the near-surface layer comprises: Using the second DAC curve as a reference sensitivity, setting the scanning sensitivity to be 6 dB higher than the reference sensitivity; An ultrasonic detector is used to perform ultrasonic testing on the near-surface layer based on a dual-crystal straight probe, all echo signals with a level greater than the second DAC curve are recorded, and the recorded echo signals are evaluated with reference to the reference sensitivity.

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