Nd:YAG welding of Cobalt to mild steel

[concutter]

We have a process where we run pulse welds of ~40 Mil diameter spots across a Cobalt to mild steel(hardened) seam interface. At one point we had good, clean, smooth welds, but recently we are getting a large generation of soot, carbon, spitting, pitting, and slag on/around our weld interface. We don't use a shield gas and we have two air knives progressively over the weld. Even with this set up, we still get spatter on the lens shield. Do anyone know what can be causing this? I am told our material quality hasn't changed any, and I have cleaned our samples in different solvents prior to weld to remove any exterior contaminants. If we run hot, we get good weld strength, but poor weld quality. Any suggestions???

Thanks!!!

 

[FGreen]

Hi,

This may or may not be of use to you, but i had a vaguely similar problem with weld quality on St/St after many hours of "problem free" (yes it does exist!) Nd-YAG welding. Although the monitoring system of our laser was supposed to highlight/counteract any degredation of the flash tubes it didn't! We swapped over tubes for new ones and rectified problem immediately.

Fraser