Laser welding of thin sheet steel with surface oxidation
Abbreviated Journal Title
ND-YAG; TEMPERATURE; CO2; Metallurgy & Metallurgical Engineering
The joining of thin sheet steel generally involves conduction mode welding, in which the reflection of the laser beam by the sheet surface is high. The absorption of laser energy by the workpiece increases significantly during keyhole laser welding, in which a vapor-plasma-filled cavity is formed. The reflectivity of cold-rolled thin sheet steel was found to be in the range of 65-80% in CO2 laser welding. The reflectivity decreased to about 30% when the sheet surface was oxidized before laser welding. In the laser welds with surface oxidation, the oxygen inclusions and porosity were not found, but the grain size was large. However, the tensile strength of all welds - with or without surface oxidation - was higher than the base metal. The toughness of the welds with surface oxidation degraded, because of the small amount of oxygen content, but it was still comparable to the toughness of the welds without surface oxidation. The oxygen content in the welds with surface oxidation was found to be slightly higher than in the welds without surface oxidation. The mechanical properties of the welds with surface oxidation were found to improve when steel powders consisting of manganese and silicon were used during welding.
"Laser welding of thin sheet steel with surface oxidation" (1999). Faculty Bibliography 1990s. 2906.