Effect of Beam Energy on Weld Geometric Characteristics in Nd:YAG Laser Overlapping Spot Welding of Thin AISI 304 Stainless Steel Sheets

Abstract

Weld geometric characteristics in laser overlapping spot welding of 0.6-mm AISI 304 stainless steel sheets were investigated. A pulsed Nd:YAG laser with maximal average power of 150 W was used for welding experiments with different laser beam energies in the range of 3.5 J to 6.2 J, keeping all other processing parameters constant. The main objective of these experiments was to study the effect of energy changes and to identify the welding mode in dependency on the beam effective peak power density. Each weld surface and its cross section were analyzed using a laser scanning confocal microscope. The spot diameter on the specimen, weld width, and penetration depth were measured. Three-dimensional surface reconstruction was realized to describe the effect of energy changes on weld surface properties.

Effect of Pulse Length on Engraving Efficiency in Nanosecond Pulsed Laser Engraving of Stainless Steel

“…[11] Pulse energy was calculated by dividing power with PRR. These parameters are compiled in Table I.…”

Effect of energy transfer modes on solidification cracking in pulsed laser welding

“…The transition mode lies in between conduction and keyhole modes where the keyhole is unstable. 18,21 Microstructural analysis of solidification cracks…”

“…However, at the same heat input condition, cracking severity is influenced by mode of energy transfer. The cooling rates achieved in different energy transfer mode welds were estimated by the relationship between mean intercellular spacing and cooling rate given by Katayama et al 22 This relation is given as l580DT 20.33 , where l is the primary arm spacing or mean inter cellular size in mm and DT is the cooling rate in K s 21 . The intercellular spacing was measured on the cross-sectional microstructure of the welds on the cellular and cellular dendrites from fusion line.…”

Pulsed Laser Welding

“…When power density balances around the critical point 10 6 W.cm -2 , produced welds are deeper than in the case of the conduction welding. Aspect ratio is about 1:1 that indicates penetration mode welding (Lapšanská et al, 2010).…”