Method for detecting defects at fusion line of wear-resistant layer of blade

Abstract

The invention belongs to the field of nondestructive testing, and particularly relates to a method for detecting defects at a fusion line of a blade wear-resistant layer. According to the technical scheme, the method for detecting the defects at the fusion line of the wear-resistant layer of the blade comprises the following steps: (1) preparing a test plate; 2) preparing a probe; (3) carrying out an eddy current detection test on the test plate; and 4) detecting the fusion line of the wear-resistant layer of the blade. According to the method for detecting the defects at the fusion line of the wear-resistant layer of the blade, the surface and near-surface defects at the fusion line of the wear-resistant layer of the blade can be effectively detected, potential quality hazards of the blade are eliminated, the machining quality of the blade is effectively monitored, and the quality of the installed blade is guaranteed.

Description

Technical Field

[0001] The invention belongs to the field of nondestructive testing, and in particular relates to a method for detecting defects at a fusion line of a blade wear-resistant layer. Background Art

[0002] During the processing of the blade wear-resistant layer, the magnetic material wear-resistant layer and the non-magnetic material blade substrate are combined together by welding technology, and unfused defects often occur at the fusion line between the wear-resistant layer and the blade substrate. During the processing, fluorescent penetrant testing is mainly used to detect defects in the wear-resistant layer and the fusion line. However, since the fluorescent penetrant testing method can only detect surface opening defects, it cannot effectively detect defects such as unfused defects on the surface of the fusion line between the wear-resistant layer and the substrate. When the conventional eddy current detection method is used to detect the fusion line of the wear-resistant layer, since the fusion line is the combination area of ​​the magnetic material and the non-magnetic material, the edge effect of the fusion line is obvious during the detection process, the interference signal is large, and the defect signal of smaller size cannot be identified in the interference signal, resulting in the failure of eddy current detection; and since the wear-resistant layer is in the concave R area with a smaller blade size, the conventional eddy current detection probe cannot be effectively scanned; in addition, due to the small size of the wear-resistant layer, it is difficult to ensure the consistency of the coupling between the detection coil and the surface to be inspected during the scanning process. Summary of the invention

[0003] The present invention provides a method for detecting defects at the fusion line of the blade wear-resistant layer, which can effectively detect surface and near-surface defects at the fusion line of the blade wear-resistant layer, eliminate hidden dangers of blade quality, realize effective monitoring of blade processing quality, and ensure the quality of installed blades.

[0004] The technical solution of the present invention is as follows:

[0005] A method for detecting defects at a fusion line of a blade wear-resistant layer comprises the following steps:

[0006] 1) Prepare a test plate; mill a step plane on the blade base material, weld the wear-resistant layer on the step plane, and then perform milling to remove excess solder and base material to obtain a welding test plate containing a fusion line of two materials, and artificially cut a groove locally on the fusion line of the wear-resistant layer to simulate a defect, and the length direction of the artificial groove is the direction of the fusion line;

[0007] 2) Prepare the probe; the outer dimensions of the probe should be smaller than the spatial dimensions of the blade concave R zone, so that the detection probe can reach the fusion line of the wear-resistant layer. The size of the coil in the probe and its position on the probe should cover the entire fusion line within the action range of the eddy current field, ensuring that all surfaces to be inspected of the wear-resistant layer fusion line are detected and no detection is missed during the detection process; when preparing the probe, the coil is shielded with a metal round tube and then encapsulated in hard plastic to reduce the influence of the blade structure edge on the eddy current field and improve the sensitivity of eddy current detection;

[0008] 3) Performing an eddy current detection test on the test plate; using the probe to scan the fusion line between the magnetic material wear-resistant layer and the non-magnetic material matrix of the test plate, and adjusting the phase of the eddy current detection signal of the wear-resistant layer fusion line to the horizontal direction by adjusting the phase button of the eddy current detector; performing an eddy current detection test on the test plate in the frequency range of 100KHz-2MHz, with a test frequency interval of 50KHz, respectively scanning the wear-resistant layer fusion line and the artificial groove on the test plate, comparing the signal amplitude, phase, signal-to-noise ratio, stability, and repeatability at different frequencies, and selecting a test frequency of 1500KHz as the detection frequency; scanning the artificial groove on the test plate at a detection frequency of 1500KHz, adjusting the vertical / horizontal ratio of the eddy current detector so that the artificial groove signal has a larger phase angle with the horizontal direction, so that the defect signal and the fusion line signal can be clearly distinguished in phase;

[0009] 4) Detect the fusion line of the blade wear-resistant layer; use the probe to scan the fusion line of the magnetic material wear-resistant layer and the non-magnetic material substrate of the blade at a detection frequency of 1500KHz, and judge whether there is a defect at the fusion line of the blade wear-resistant layer by whether the signal of the eddy current detector has a large phase angle with the horizontal direction.

[0010] Furthermore, in the method for detecting defects at the fusion line of the blade wear-resistant layer, the probe is a differential eddy current detection probe.

[0011] The beneficial effects of the present invention are as follows: the present invention effectively distinguishes the defect signal at the fusion line from the fusion line interference signal by analyzing and processing the eddy current detection process and the detection signal; at the same time, the eddy current detection coil winding method and the probe shape structure are improved according to the detection parameters and the detection results, and the effective detection of the fusion line of the wear-resistant layer in the concave R area is achieved under the premise of ensuring the consistency of the coupling between the detection coil and the surface to be inspected during the detection process. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The wear-resistant layer fusion line signal adjusted to the horizontal direction displayed by the eddy current detector;

[0013] Figure 2 The artificial groove signal displayed by the eddy current detector has a large phase angle with the horizontal direction. DETAILED DESCRIPTION

[0014] A method for detecting defects at a fusion line of a blade wear-resistant layer comprises the following steps:

[0015] 1) Prepare a test plate; mill a step plane on the blade base material, weld the wear-resistant layer on the step plane, and then perform milling to remove excess solder and base material to obtain a welding test plate containing a fusion line of two materials, and artificially cut a groove locally on the fusion line of the wear-resistant layer to simulate a defect, and the length direction of the artificial groove is the direction of the fusion line;

[0016] 2) Prepare the probe; the outer dimensions of the probe should be smaller than the spatial dimensions of the concave R area of ​​the blade, so that the detection probe can reach the fusion line of the wear-resistant layer. The size of the coil in the probe and its position on the probe should cover the entire fusion line within the action range of the eddy current field, ensuring that all surfaces to be inspected of the fusion line of the wear-resistant layer are detected and there is no missed detection during the detection process; when preparing the probe, the coil is shielded with a metal round tube and then encapsulated in hard plastic to reduce the influence of the edge of the blade structure on the eddy current field and improve the sensitivity of eddy current detection; the probe is a differential eddy current detection probe;

[0017] 3) Performing an eddy current test on the test plate; scanning the fusion line between the magnetic material wear-resistant layer and the non-magnetic material matrix of the test plate using the probe, and adjusting the phase of the eddy current detection signal of the fusion line of the wear-resistant layer to the horizontal direction by adjusting the phase button of the eddy current detector, such as Figure 1 As shown; the test plate is subjected to eddy current testing within the frequency range of 100KHz-2MHz, with a test frequency interval of 50KHz, and the wear-resistant layer fusion line and artificial groove on the test plate are scanned respectively, and the signal amplitude, phase, signal-to-noise ratio, stability, and repeatability at different frequencies are compared, and a test frequency of 1500KHz is selected as the test frequency; the artificial groove on the test plate is scanned at a test frequency of 1500KHz, and the vertical / horizontal ratio of the eddy current detector is adjusted so that the artificial groove signal has a larger phase angle with the horizontal direction, as shown Figure 2 As shown, the defect signal and the fusion line signal can be clearly distinguished in phase;

[0018] 4) Detect the fusion line of the blade wear-resistant layer; use the probe to scan the fusion line of the magnetic material wear-resistant layer and the non-magnetic material substrate of the blade at a detection frequency of 1500KHz, and judge whether there is a defect at the fusion line of the blade wear-resistant layer by whether the signal of the eddy current detector has a large phase angle with the horizontal direction.

Claims

1. A method for detecting defects at the fusion line of a blade wear-resistant layer, characterized in that: The steps include: 1) Prepare a test plate; mill a step plane on the blade base material, weld the wear-resistant layer on the step plane, and then perform milling to remove excess solder and base material to obtain a welding test plate containing a fusion line of two materials, and artificially cut a groove locally on the fusion line of the wear-resistant layer to simulate a defect, and the length direction of the artificial groove is the direction of the fusion line; 2) Prepare the probe; the outer dimensions of the probe should be smaller than the spatial dimensions of the blade concave R zone, so that the detection probe can reach the fusion line of the wear-resistant layer. The size of the coil in the probe and its position on the probe should cover the entire fusion line within the action range of the eddy current field, ensuring that all surfaces to be inspected of the wear-resistant layer fusion line are detected and no detection is missed during the detection process; when preparing the probe, the coil is shielded with a metal round tube and then encapsulated in hard plastic to reduce the influence of the blade structure edge on the eddy current field and improve the sensitivity of eddy current detection; 3) Performing an eddy current detection test on the test plate; using the probe to scan the fusion line between the magnetic material wear-resistant layer and the non-magnetic material matrix of the test plate, and adjusting the phase of the eddy current detection signal of the wear-resistant layer fusion line to the horizontal direction by adjusting the phase button of the eddy current detector; performing an eddy current detection test on the test plate in the frequency range of 100KHz-2MHz, with a test frequency interval of 50KHz, respectively scanning the wear-resistant layer fusion line and the artificial groove on the test plate, comparing the signal amplitude, phase, signal-to-noise ratio, stability, and repeatability at different frequencies, and selecting a test frequency of 1500KHz as the detection frequency; scanning the artificial groove on the test plate at a detection frequency of 1500KHz, adjusting the vertical / horizontal ratio of the eddy current detector so that the artificial groove signal has a larger phase angle with the horizontal direction, so that the defect signal and the fusion line signal can be clearly distinguished in phase; 4) Detect the fusion line of the blade wear-resistant layer; use the probe to scan the fusion line of the magnetic material wear-resistant layer and the non-magnetic material substrate of the blade at a detection frequency of 1500KHz, and judge whether there is a defect at the fusion line of the blade wear-resistant layer by whether the signal of the eddy current detector has a large phase angle with the horizontal direction.

2. The method for detecting defects at the fusion line of the blade wear-resistant layer according to claim 1, characterized in that: The probe is a differential eddy current detection probe.

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