A dynamic detection method for friction stir welding seam quality based on torque

Abstract

The invention discloses a stir friction weld joint quality dynamic detection method. First of all, torque is subjected to high-frequency sampling through a mechanical testing device, a sampling deviceand an oscilloscope, through high-frequency sampling of the torque, the torque change is displayed through the oscilloscope, then the torque between two wave crests is defined as a cycle, the changing situation of the torque in each cycle is sampled and analyzed, each cycle is divided into two parts, the time when the wave crests fall to wave troughs is A, the time when the wave troughs rise to the wave crests is B, finally, A / B is calculated and analyzed, a relational expression 0.8<A / B<1.3 is analyzed, and then whether a weld joint produces defects or not is judged. According to the stir friction weld joint quality dynamic detection method, the stir friction weld joint quality is subjected to dynamic detection based on the torque change, the method is simple and easy, the cost is low, large monitoring equipment investment is not required, and destructive experiments are not required.

Description

technical field [0001] The invention belongs to the field of friction stir welding seam quality analysis, and specifically provides a method for real-time monitoring of friction stir welding seam quality based on torque variation. Background technique [0002] Friction Stir Welding (FSW) uses a special form of stirring head to advance while rotating, and generates heat through the friction between the stirring head and the workpiece. The friction heat makes the metal in this part in a thermoplastic state, and the pressure of the stirring head Under the action, it flows plastically from the front to the rear, so that the parts to be welded are pressure-welded as a whole. Compared with traditional welding methods, friction stir welding has the advantages of high joint quality, small welding deformation, small residual stress, and no pollution during welding. It is the preferred welding method for light alloys such as aluminum and magnesium. Therefore, since 1991, the British w...

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Problems solved by technology

However, these detection methods have their own defects. Eddy current and penetration testing can effectively detect weld surface defects, but are not suitable for detecting weld internal defects (such as tunnel defects, looseness, etc.)

Radiographic inspection is better for the detection of larger tunnel-type defects, but it cannot detect small loose, incomplete penetration and tight-fitting defects

Ultrasonic nondestructive testing can detect tunnel-type defects, incomplete penetration defects, and fine porosity, but the equipment is relatively expensive (see Lu Jia, Xu Wei, Zheng Xingwei. Research progress in friction stir welding weld defect detection[J]. Thermal Processing Technology, 2017 (13):23-25.)

Moreover, the detection methods mentioned above can only detect the weld seam after the welding is completed, and cannot perform a dynamic real-time monitoring of the welding process.

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