Plasma Arc Augmented CO2 laser welding

In order to reduce the hardness of laser beam welded 2.13 mm medium strength steel CMn 250, a plasma arc has been used simultaneously with a 2.6 kW CO2 laser source. In a number of systematic laboratory tests, the plasma arc current, plasma gas flow and distance to the laser source were varied with all laser parameters fixed.

The welds were quality assessed and hardness measured transversely to the welding direction in the top, middle and root of the seam. In the seams welded by laser alone, hardness values between 275 and 304 HV1 were measured, about the double of the base material, 150 HV1. With the addition of a plasma arc, the hardness could overall be reduced to between 200 and 220 HV1, i.e. about 27 percent.

In the seam middle, the reduction was 36 percent.