Nd:YAG laser spot welding of very thin stainless steel and micro x-ray characterization of welds

Abstract

Very thin (< 0.1 mm, thick) austenitic stainless steel (AISI 316) sheets were spot welded in a lap joint configuration using a pulsed Nd:YAG laser of maximum average power 400 W. A 127 mm, focal length lens was used to produce a spot size of 0.3 mm diameter. The assist gas, argon, was used at 40 psi (280 kPa) pressure and 70 cfh (551 cc/s) flow rate. Spot-welded samples were produced for different beam intensities by varying the pulse energy in predetermined steps. The samples were destructively tested by conducting tension-shear and U-tension tests. They were also non-destructively tested using micro X-ray imaging technique and the National Institute of Health (NIH) image processing software. The pixel intensities of the micro X-ray images were correlated with the strength values obtained from the destructive tests. Good quality welds with strength of 80% - 90% that of the base metal were produced.Very thin (< 0.1 mm, thick) austenitic stainless steel (AISI 316) sheets were spot welded in a lap joint configuration using a pulsed Nd:YAG laser of maximum average power 400 W. A 127 mm, focal length lens was used to produce a spot size of 0.3 mm diameter. The assist gas, argon, was used at 40 psi (280 kPa) pressure and 70 cfh (551 cc/s) flow rate. Spot-welded samples were produced for different beam intensities by varying the pulse energy in predetermined steps. The samples were destructively tested by conducting tension-shear and U-tension tests. They were also non-destructively tested using micro X-ray imaging technique and the National Institute of Health (NIH) image processing software. The pixel intensities of the micro X-ray images were correlated with the strength values obtained from the destructive tests. Good quality welds with strength of 80% - 90% that of the base metal were produced.