RU1786417C - Method of magnetic testing of butt joints - Google Patents

Abstract

The invention relates to the field of non-destructive testing by the magnetic method and can be used in the quality control of butt welded joints. The purpose of the invention is to increase the reliability of control of the seam sections at the ends of the product. The goal is achieved due to the fact that the technological plates made of the material of the controlled product with a thickness equal to the thickness of the latter are docked to the controlled product, the welded seam with the adjacent heat-affected zone is magnetized with a U-shaped electromagnet, and magnetization begins when one pole is located outside the product on the technological plate and the magnetization is completed, when both poles are outside the product on another technological plate, the topography of the magnetic relief is read to The area to be monitored and the magnetogram determine the presence of defects. 1 ill.

Description

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The invention relates to non-destructive testing by the magnetic method and can be used in the quality control of butt welded joints (mainly panels of tanks, gas holders, etc.).

A known method of magnetic control of butt welded joints is that the weld is magnetized in the transverse direction by a U-shaped electromagnet, the poles of which are located on opposite sides of the weld, fix the scattering magnetic fields, according to which the quality of the welded joint is judged .

A disadvantage of the known method is the low reliability of inspection of welds for the presence of local defects (pores, slag inclusions).

The closest technical solution to the invention is a method of magnetic control of butt welded joints, which consists in the fact that a weld with an adjacent near-weld zone is magnetized with a U-shaped electromagnet along the weld, and the magnitude of the magnetizing field is selected in the range of 50 ... 90 A / cm the topography of the magnetic relief of the area being monitored is read and the presence of defects is determined from the magnetogram.

A disadvantage of the known method is the low reliability of the control of the seam sections at the ends of the product, which is due to the following.

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In the extreme position of the electromagnet, when one pole is located at the edge of the product, the parts of the product located under the poles are magnetized by a field directed perpendicular to the surface of the product, and therefore their control is not significant. If the magnetizing device is shifted so that the pole extends beyond the product, then due to the significant magnetic resistance of the part located in the interpolar space (part of the product plus air gap), the seam section at the end of the product will be slightly magnetized, which will reduce the reliability of the control .

The aim of the invention is to increase the reliability of the inspection of the seam sections at the ends of the product.

This goal is achieved by the fact that in the method of magnetic control of butt welded joints, namely, that a weld with an adjacent parietal zone is magnetized with a U-shaped electromagnet along the weld, the topography of the magnetic relief of the controlled area is read and the presence of defects is determined from the magnetogram they attach technological plates from the material of the controlled product with a thickness equal to the thickness of the latter to the controlled product, magnetization begins when one field is found They are outside the product on the technological plate and the magnetization is completed when both poles are outside the product on the other technological plate.

The invention is illustrated in the drawing.

With the proposed method, the technological plates are docked to the beginning and end of the product in the control zone with a minimum gap, the magnetization of the product begins when one pole of the electromagnet 1 is outside the product 2 on the technological plate 3. The product is magnetized by moving the magnetizing device in the direction of the arrow And along the seam, the magnetization ends when both poles are outside the product on the technological plate 4. In this case, the maximum induction in the weld will depend on the magnesium the resistivity magnetizable portion. Moreover, in each particular position of the magnetizing device, the maximum value of induction will be observed at the poles of the electromagnet. Because in the presence of technological plates made of

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of the same material and the same thickness as the controlled product, magnets, the resistance of the magnetized part of the product (or the part of the product and the part of the process plate) will be approximately the same for an arbitrary arrangement of the electromagnet, then the initial and final sections of the weld will be magnetized to the same maximum induction .

PRI me R 1, a Sample of 350 x 250 x 6 mm in size was made of steel St.3 containing a weld bead 10.1 mm wide and 2.2 mm high. At the root of the seam, recesses were drilled that simulated pores of 25% of the thickness. The diameter of the artificial continuity defect was 1.0 mm. The sample was magnetized during the control by a device based on PNU-1 (the number of turns of the winding wire was 600, the diameter of the wire was 1.5 mm, the pole section was 120 x 20 mm). The control was carried out by the method adopted for the prototype using magnetic tape type I4701-35. The defect was found everywhere, except for the initial and final sections of the weld.

EXAMPLE 2, The same sample was controlled by the proposed method. Technological plates with dimensions of 250 x 150 x 6 mm and 100 x 150 x 6 mm were used. The defect was detected at an arbitrary spot in the weld, and the signal amplitude from the same defects was the same.

The application of the proposed method of magnetic control will improve the reliability of the control of the seam sections at the ends of the product for the presence of pores and slag inclusions.

Claims (1)

The claims The method of magnetic control of butt welded joints, namely, that a weld with an adjacent near-weld zone is magnetized with a U-shaped electromagnet along the weld, the topography of the magnetic relief of the area being inspected is read and the presence of defects is determined from the magnetogram, in order to increase the reliability control of the seam sections, at the ends of the product, technological plates from materials of the controlled product with a thickness equal to the thickness of the last are docked to the controlled product Oh, when the magnetization of the start of one pole on the outside of the product technology and end plate magnetization when both poles okazhuts outside of the product on the other plate technology. AND 2