Relation between Plasma Electrical Signal Oscillation and Weld Depth in Laser Deep Penetration Welding

XU Sai1 YANG Lijun1,2 XU Shufeng3 HUANG Yiming1 ZHAO Shengbin1 LI Shanshan1

(1.School of Material Science and Engineering, Tianjin University, Tianjin, China 300350)
(2.Tianjin Key Laboratory of Advanced Joining Technology, Tianjin University, Tianjin, China 300350)
(3.Stainless Cold Rolling Mill, Shanxi Taigang Stainless Steel Co., Ltd., Taiyuan, Shanxi Province, China 030003)
【Knowledge Link】bremsstrahlung

【Abstract】In this study, the relation between keyhole oscillation and depth is analyzed based on the internal pressure balance conditions of the keyhole to allow real-time monitoring of the laser penetration welding process. Then, based on the coupling of keyhole behavior with plasma behavior and consistency of plasma oscillation characteristics with plasma electrical signal fluctuation characteristics, we use a short-time autocorrelation analysis method for the relation between the oscillation period of a plasma electrical signal and weld depth during laser penetration welding of A304 stainless steel and Q235 carbon steel. Results show that the plasma electrical signal’s oscillation period increases with the rise in the weld depth, and the relations between the plasma electrical signal’s oscillation period and weld depth differ when the welding materials are different. Finally, in a verification test of continuous welding with variable heat input, we obtain a good correspondence between the short-time autocorrelation analysis results of plasma electrical signals and weld penetration when the welding process is stable, which is consistent with the characteristic equation of keyhole oscillation in our analysis.

【Keywords】 laser optics; laser penetration welding; weld depth prediction; short-time autocorrelation analysis; plasma electrical signal;

【DOI】

【Funds】 National Natural Science Foundation of China (51875403)

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This Article

ISSN:0258-7025

CN: 31-1339/TN

Vol 47, No. 01, Pages 113-121

January 2020

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Abstract

  • 1 Introduction
  • 2 Theoretical basis and analysis method
  • 3 Results and discussion
  • 4 Conclusion
  • References