Far-field eddy current probe and method for dissimilar steel weld defect detection

Abstract

The invention discloses a far-field eddy current probe and method for dissimilar steel weld defect detection, the far-field eddy current probe comprises an excitation unit, a detection unit, a shielding unit, a signal connection joint and a probe shell, the excitation unit is formed by placing an excitation coil in an excitation magnetic conduction structure; the detection unit is formed by tightly and circumferentially winding a detection coil on the peripheral surface of a detection magnetic conduction structure, and the shielding unit is formed by a multi-layer composite shielding structure. A special conformal probe structure is developed for a complex pipeline structure at a dissimilar steel weld joint, detection can be completed in a narrow space, and signal interference caused by a reducing section and a thermocouple is avoided; multi-signal channel time-sharing detection is adopted, excitation units and detection units between adjacent signal channels are placed in opposite directions, and it is ensured that eddy current signals can be excited and received by the two sides of a dissimilar steel welding seam; during detection, the probe rotates a circle around the dissimilar steel weld joint to realize far-field eddy current detection of weld joint defects, and the detection efficiency is improved.

Description

Technical field [0001] The present invention involves the field of welding seam lossless detection technology, especially a far -field vortex probe and method for detection of heterogeneous steel weld defect detection. Background technique [0002] The connection pipe at the end of the furnace at the furnace of the thermal power unit adopts the heterogeneous steel structure, which is welded by the pipelines of the two materials. It is affected by the welding process and the service environment. The pipeline is damaged and leaked, which then affects the service life of the equipment and the safe operation of thermal power unit. Therefore, it is of great significance to detect the health state of the heterogeneous steel docking weld in time. [0003] At present, for the healthy state detection of heterogeneous steel welds, there are mainly the following limits: First, the problem of narrowing the detection space at the complex pipeline structure at the heterogeneous steel weld. The...

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Problems solved by technology

[0002] The connecting pipe at the re-exit of the furnace end of the thermal power unit adopts a different diameter and dissimilar steel structure, which is welded by pipes of two materials. Due to the influence of the welding process and service environment, the butt weld at the dissimilar steel connection is prone to harmful defects, resulting in Pipeline damage and leakage will affect the service life of equipment and the safe operation of thermal power units. Therefore, it is of great significance to detect the health status of dissimilar steel butt welds in time

[0003] At present, there are mainly the following limitations in the detection of the health status of dissimilar steel welds: firstly, the complex pipeline structure at the dissimilar steel welds causes the problem of narrow detection space. There is a variable diameter section on the lower side of the dissimilar steel weld, and in order to monitor the temperature change of the pipeline, a thermocouple is installed on the upper side of the dissimilar steel weld, so limited by the influence of the variable diameter section and the thermocouple, local point detection technologies such as ultrasonic testing exist Some detection sites are not accessible

The second is the problem of defect detection depth. Dissimilar steel welds are automatically welded by argon arc, and the appearance and root of the weld are well formed. However, due to the influence of welding quality and service environment, cracks mostly originate at the root of the weld and the fusion line on the inner wall of the pipeline. Therefore, For the detection of deep defects in welds, surface defect detection methods such as penetrant testing and eddy current testing are difficult to achieve

At the same time, there is the problem that the efficiency of defect detection is not high enough. The furnace end pipeline is densely arranged and the space is narrow. The radiation detection method needs to place the radiation source and film, and the magnetic particle detection needs to treat the surface. The time cost of both is high.

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