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A method for on-line monitoring of resistance change of metal brazed joints

A technology of brazing joints and welding joints, which is applied in the field of non-destructive evaluation, can solve the problems of not reflecting the welding conditions of brazing joints well, and the detection accuracy of brazing rate is not high, so as to achieve intuitive and clear measurement results, simple results, and convenient operation Effect

Active Publication Date: 2018-03-30
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The existing detection methods for brazed joint defects have limitations, especially the detection accuracy of the brazing rate of the brazed joint is not high, and cannot well reflect the welding condition of the entire brazed joint

Method used

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  • A method for on-line monitoring of resistance change of metal brazed joints
  • A method for on-line monitoring of resistance change of metal brazed joints
  • A method for on-line monitoring of resistance change of metal brazed joints

Examples

Experimental program
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Effect test

Embodiment 1

[0043] In this embodiment, 304 stainless steel is selected as the brazing base material, and its size is 10mm×80mm×1mm. Choose AgCuTi metal foil (melting point: 800℃~820℃) as the solder.

[0044] When brazing, lap the 304 stainless steel base material along the length direction, the lap length is 10mm. Before welding, use 1000# sandpaper to smooth the surface to be welded, and then use alcohol ultrasonic cleaning for 15min to dry. Assemble the prepared materials in the form of 304 stainless steel / Ag-Cu-Ti / 304 stainless steel. The test is carried out in a vacuum diffusion soldering furnace with a vacuum degree of 1.0×10 -2 -1.0×10 - 3 Pa. The heating temperature is 870℃, the holding time is 20-50min, and the connection pressure is 0.05MPa.

[0045] The solder AgCuTi and 304 stainless steel vacuum brazing process is: heating at 10℃ / min to 820℃, holding for 30min, and then continuing to heat at 10℃ / min to 870℃, starting to keep the temperature, holding time respectively 5min, 10min...

Embodiment 2

[0055] A non-destructive testing method and device for on-line monitoring of the resistance value of metal brazing joints and indirect evaluation of joint performance, including: brazing joints to be tested, four-point probes, ceramic wires, fixtures, lifting devices with universal heads, Four probe resistance meter and computer. The brazing sample to be tested includes the base material area of ​​the brazing joint and the brazing joint area of ​​the brazing joint. The brazing joint area of ​​the brazing joint to be tested is located in the middle of the lap joint. The area of ​​the four-point probe is smaller than that of the brazing joint. The area of ​​the seam area. The four-point probe is composed of four metal electrode rods and a ceramic shell. The four metal electrode rods are distributed in parallel. The four-point probe is fixed on the lifting device with universal head. The signal is connected to the signal collection terminal of the four-probe resistance meter throu...

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Abstract

The invention discloses a method for online monitoring resistance change of a metal soldered joint, in particular a nondestructive testing method and device for online monitoring the resistance change of the metal soldered joint and indirectly evaluating the performance of the joint. Firstly, the position of a four-pin probe is adjusted, so that the contact between a brazing seam and four points of pins is excellent. The soldered joint is fixed by a fixture; the four-pin probe is fixed by a lifting device with a universal head; resistance signals are acquired by using a ceramic lead; finally, the acquired resistance signals are analyzed by a computer to output a curve chart with resistance changing along with time; process parameters are changed; the resistance change of the joint under different process parameters is found out according to the curve chart to indirectly evaluate the performance of the joint to rate the joint; and the method also can be matched with a traditional detecting method and other nondestructive testing for use, so that the resistance detecting accuracy of the metal soldered joint in a nondestructive state is guaranteed, and the problem that the performance of the metal soldered joint is difficult to evaluate after brazing is solved.

Description

Technical field [0001] The invention relates to the technical field of non-destructive evaluation, and in particular provides a method and device for on-line monitoring the resistance of a metal brazing joint and indirectly evaluating the performance of the brazing joint. Background technique [0002] Today, with the rapid development of welding technology, brazing has become one of the most widely used connection technologies. The advantages of brazing are the smooth surface of the joint, good air tightness, stable shape and size, and the brazing joint has other connection methods. It has the characteristics, so it is widely used in aerospace, military submarine and other important occasions, but brazed joints also have various defects. Pores (voids) are one of the most common defects, manifested as holes on or inside the brazing joint. If the cross-sectional area of ​​the joint is lost by 5% due to pores, the joint strength will drop by 30%; the pore distribution parallel to t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B23K31/12B23K1/008B23K1/20B23K103/04
CPCB23K1/008B23K1/20B23K1/206B23K31/125B23K2103/04
Inventor 李红乔巧黄海新杨林派
Owner BEIJING UNIV OF TECH