Press Forge Welding

[char8726]

I'm having issues with press forge welding. The material is SUP9 and heated to 1050 C before pressing. I am using a hydraulic press. I have attached a picture below of the weld joint. As you can see there are three distinct gaps. Any help would be appreciated.

 

[metengr]

What is your surface prep and force applied? The key is to have surfaces that are relatively smooth, and clean in contact with one another so that material is forced outward from the heated surface to create flashing. This weld is no different than pressure induction welds. I don't believe your pressure was high enough.

 

[char8726]

I'm currently using a 250 ton hydraulic press. I've done a forging force calculation and calculated 20,388 kgf needed for a 24.4mm solid bar at 1000 deg C (8kgf/mm^2).
The material being pressed is a pipe end, OD 24.4mm, ID 16mmm. So the force required should be even lower.
These are samples of previous trials done before w/o any surface prep. I'm pretty sure the lack of surface prep caused the previous failures. I currently am ordering fluxes (anhydrous borax, silica, boric acid) to apply to the interior of the pipe during heating. About the smooth contact surfaces, I don't know how much surface prep I can do to pipe end interior.