Detection and characterization method for plastic flow characteristic of weld metal in friction stir welding process

Abstract

The invention provides a detection and characterization method for the plastic flow characteristic of weld metal in the friction stir welding process. The detection and characterization method can overcome the defects of existing characterization methods and can achieve non-destructive, convenient and rapid detection and characterization of the plastic flow characteristic of the weld metal in theFSW process. The detection and characterization method specifically comprises the steps that before butt welding in the stir friction welding process, at least three pure copper wires are embedded into the to-be-welded side of base metal on the advancing side and the retracting side to serve as marking materials, wherein the diameter of each copper wire is 1.0-1.5 mm, the length of each copper wire is greater than the radius of the shaft shoulder of a stirring head; the copper wires are perpendicular to the stirring head and the welding direction and are spaced from one another by at least 10mm in the welding direction and evenly distributed in the thickness direction; and three-dimensional computed tomography scanning is conducted on a weld joint through the industrial computed tomography (ICT) after friction stir welding, and the three-dimensional topography is obtained after the copper wires deform and used for characterizing the plastic flow characteristic of the weld material ofthe base metal in the friction stir welding process. The detection and characterization method for the plastic flow characteristic of the weld metal in the friction stir welding process has the advantages that a welded sample is not damaged, operation is safe, the practicability is high, and the plastic flow characteristic of the material in the friction stir welding process can be characterized rapidly and accurately.

Description

technical field [0001] The invention relates to friction stir welding technology, in particular to a detection and characterization method for the plastic flow characteristics of friction stir welding weld metal. Background technique [0002] Friction Stir Welding, or Friction Stir Welding (abbreviated as "FSW", for a more concise description, "FSW" will be used instead of "Friction Stir Welding" below), is a solid phase welding technology invented by the British Welding Institute in 1991. , the principle is to insert the rotating stirring head into the weldment, move forward while rotating, stir the base metal by rotating, and generate heat due to friction to cause plastic flow of the welded materials and finally weld them together. During the FSW process, the base metal will not melt, so it can avoid the liquid splash, cracks, pores and other defects caused by traditional fusion welding. It has been widely used in the welding of low melting point light alloy materials such...

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Problems solved by technology

However, in order to observe the changes of the embedded marking materials after welding, it is often necessary to use the method of intercepting the weld section to obtain a metallographic sample for observation, which not only needs to destroy the sample, but also makes it difficult to observe the whole picture of the marking material; X-ray transmission real-time imaging is used to observe the changes of marking materials, but the equipment is expensive, and in order to prevent X-ray leakage during the experiment, the experimental protection requirements are very high, and the usability in engineering practice is not strong.

[0008] In summary, the existing detection methods for the plastic flow of weld metal in the FSW process can be roughly divided into two situations, one is that the welding sample needs to be destroyed, the operation is cumbersome, and the experimental results are inaccurate; the other does not need to destroy the sample, but The experimental equipment is expensive, the requirements for the experimental conditions are high, and the practicability is not strong

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