Non-destructive evaluation of laser welds in tailor-welded blanks using magnetic flux leakage

Abstract

The tailor-welded blank (TWB) industry, which uses laser welding exclusively, is facing higher demands on quality assurance, both internally to raise efficiency of production lines and externally from their customers (predominantly auto makers). This paper introduces a novel, economical approach to TWB inspection, which employs the principle of magnetic flux leakage (MFL). The development of a laboratory-based MFL inspection tool for TWBs is presented. The effects of inspection system operating parameters are quantified to allow for optimized and robust performance. The operating parameters examined include applied magnetic field strength, scanning velocity, and sampling resolution. The ability of the MFL technique to detect defects that occur in the production environment from CO2 and Nd:YAG welds is clearly demonstrated. Defects include porosity, missed weld, pinholes, mismatch, concavity, and convexity. The issues of robustness and reliability surrounding the implementation of an industrial MFL inspection tool are addressed and suitable recommendations for further development are made.The tailor-welded blank (TWB) industry, which uses laser welding exclusively, is facing higher demands on quality assurance, both internally to raise efficiency of production lines and externally from their customers (predominantly auto makers). This paper introduces a novel, economical approach to TWB inspection, which employs the principle of magnetic flux leakage (MFL). The development of a laboratory-based MFL inspection tool for TWBs is presented. The effects of inspection system operating parameters are quantified to allow for optimized and robust performance. The operating parameters examined include applied magnetic field strength, scanning velocity, and sampling resolution. The ability of the MFL technique to detect defects that occur in the production environment from CO2 and Nd:YAG welds is clearly demonstrated. Defects include porosity, missed weld, pinholes, mismatch, concavity, and convexity. The issues of robustness and reliability surrounding the implementation of an industrial MFL inspect...