[TheForge] Welding and grease

[John McPherson]

Forge welding is done by (comparatively slowly) bringing two separate pieces 
just barely up to a welding heat over the complete surface to be welded. 
This gives time for lots of scale formation, contamination, etc. and the 
flux is there to prevent this, and gets squeezed out during the actual 
welding of the two clean surfaces. Thin grease as a flux might burn off 
during the heating cycle, using up the oxygen and leaving a fairly clean 
surface, but the timing would be critical.

Electric or oxy/fuel welding is much like making new steel in a very small, 
fast, mobile furnace. A clean weld can be stronger than the base metal. 
Because you are using so much excess heat, you have to keep moving or melt 
thru. This does not leave time to fully vaporize oil, crud, paint, etc. so 
it gets mixed into the steel melt. Shielding gas or flux is just there to 
prevent atmospheric contamination, and is no substitute for clean metal. 
Clean metal + good filler rod + good shielding + good technique add up to a 
good weld. Leave out one of those and it may look OK, but....

Clear as mud?
John McPherson

>
>
>This brings up yet another thing that leaves me even more confused...to
>wit...
>If one contaminates a torch or tig weld with oil or grease it gets ugly
>usually....hard to get the weld to take......
>Why isn't that the case with forge welding?....Pete F
>