Forge welding has often been a confidence shaker for blacksmiths. While it does take some thought and planning, it is not the mystical union of metals you may have thought. There are several key factors in forge welding in the Forgemaster TM.
1) Pre-heat the forge by increasing the regulator pressure to 12-15 psi. Allow the forge to run at this pressure while you are forging the scarf and preparing the steel for the weld.
Forge & Anvil Preparation
2) Pre-heat the anvil by forging or by heating a large piece of steel and laying it on the anvil face. A cold anvil will rapidly draw the heat away from the weld, which will result in a failure to weld.
If pre-heating the anvil is not practical, you might try placing a small amount of welding flux on the face of the anvil at the spot where you will weld. The flux will serve as a brief insulator to assist your weld.
3) Proper shaping of the areas to be welded (scarf) is an important part of proper forge welding.
A finely feathered edge will hide the weld, avoiding "cold shuts".
Be sure to lap the weld area so that there is sufficient material to hammer together and avoid a thin weld area.
4) After the scarf is prepared place the material into the Forgemaster TM forge, with the area to be welded under one of the burners. Avoid allowing the weld area to lay directly on the brick hearth, as the heat must be allowed to "wrap" around the weld area.
Welding Heat & Flux
Avoid resting the weld area on the brick hearth.
Setting the weld area directly under the flame with space beneath the weld are and the brick will make forge welding easier.
5) Bring the material up to welding temperature. If the forge has been operating at 12-15 p.s.i. while you were preparing the scarf, you should have welding heat in about 30 seconds. When welding heat is reached remove the steel from the fire and quickly brush the weld area with a heavy steel brush to remove excess scale. Quickly apply flux and return to the fire. This sequence should be accomplished in just a few seconds to avoid losing much heat. The longer the flux is in the fire the less effective it is.
Butcher Block brushes work well for quickly removing scale build up.
There are several good forge welding fluxes. Sure Weld and Stable Weld are two that work well.
6) After the flux is applied return the steel to the forge and regain welding heat. When welding heat is reached remove the steel from the fire and hammer the two pieces together with quick hammer blows. Your finished weld should be clean and have no weld lines.
Flat view of scarf area after welding
Edge view of scarf area before welding
Edge view of scarf area after welding