Surface inspection of joint areas by means of laser-induced breakdown spectroscopy

21st Chemnitz Seminar on Materials Engineering – 21. Werkstofftechnisches Kolloquium

Doraciak, P.^1 ; Bünting, A.^1 ; Lampke, T.^2

Process Development, Daimler AG, Stuttgart

70546, Germany^1

Institute of Materials Science and Engineering, Chemnitz University of Technology, Chemnitz

09125, Germany^2

关键词: Contaminated surfaces;    Fluorescence intensities;    Forming lubricants;    Laser welded joints;    Laser-pulse energy;    Laserinduced breakdown spectroscopy (LIBS);    Peak intensity ratio;    Process parameters;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/480/1/012006/pdf
DOI  :  10.1088/1757-899X/480/1/012006

来源: IOP

【 摘 要 】

The quality of laser welded joints is dependent on different factors like the process-parameters, weld configuration and the cleanliness of the joint area. Filmic contaminations on the joint area can be oil, grease and other lubricants, which are used for machining, corrosion protection or component assembly. Residuals of lubricants can vaporize during the laser welding process and may lead to weld smoke as well as spatters and results in welding defects like cracks and pores in the weld seam. Laser-induced breakdown spectroscopy (LIBS) was investigated successfully and applied to detect contaminants and finally avoid these welding defects. 1.7131 steel was used as model-substrate. The ground sample surfaces were characterized by means of surface energy as well as fluorescence-intensity and LIBS spectra of the cleaned surfaces were recorded. The effect of the laser pulse energy and the delay time between laser pulse and the spectra recording was investigated. Furthermore, a forming lubricant was applied on the sample surfaces and reflectometry was successfully used for the film thickness measurements. LIBS spectra of the contaminated surfaces are presented and the impacts of the oil film thickness on the appearance of the spectra are outlined. Additionally, the examination presents the evaluation of the spectra with the linear correlation and the peak intensity ratio.