I am always asked about the type of setup that I have for forge welding. I have used a Venturi burner made by Rex Price from hybridburners. It is called T-Rex and it is 3/4 inches in diameter. The performance of this burner is exceptional. People wonder if an atmospherical burner could reach welding temperatures and the answer is YES. I also feel they are safer since you don’t have to rely on electrical power.
I also use a 1 inch diameter burner from Rex in my latest welding forge. This burner is outstanding. In a well designed forge it reaches easily temperatures of 2200 degrees F at 5 psi given enough time. My pyrometer does not read above 2500 degrees so I could not get a reading as to how hot it gets. That means a significant amount in fuel savings. I am very impressed with this burner and it is my current workhorse burner for the welding forge.
This billet consists of different layers of 1095, 1050 and 15N20 steel. The initial size will vary but may go from 6 to 12 inches in length and usually 1 inch wide.
I used to tie the bars with a wire and I still do but I also use a MIG welder for holding them together. For this particular billet I have chosen the following arrangement of steels.
The outside layers get hotter sooner than the inner layers. You have to be patient and wait until all layers are evenly heated and the color of the steel approximates the color of the walls of the forge. I add some more borax as the billet gains temperature. As the billet reaches welding temp the flux bubbles and then those bubbles will start to dance on the surface of the steel. At this point the steel takes the appearance of melted butter.
That is the time to take it to the anvil and gently hammer on it in a methodic way to cover all the surface from the center to the edges of the billet. On the first welding pass is more important to me to close all the gaps and assure as good as possible contact between the layers. A nice alternative to the hammer is a hydraulic press. It is a sound idea to flip the billet on its side and hammer on it. If the weld did not take, it will delaminate. Most weld failures are due to either not reaching high enough temperature for the weld to take or impurities between the surfaces to be welded.
The billet, now a single block of steel, is drawn out to about double its original length.
After drawing out the billet I will take an angle grinder to the surface of the billet to clean it up. Alternatively, I will use flux and a metal brush to clean the surface and to prepare for the next weld.
I use a hatchet or hot cutter to split the billet in half while it is hot.
I cut through 80-90% of the billet leaving a hinge to fold it over itself so that the previously cleaned surfaces will meet each other.
The billet is then fluxed generously and put back in the forge.
Closing the gap between the folds as tightly as possible.
Sometimes I use a piece of rebar with one end forged to a tip to pick up flux and transfer the flux to the billet while it is inside the forge.
Then is waiting time until the billet reaches temperature again and is ready for the next round of hammering.
The second weld is completed.
After that is time to draw it out, clean the surfaces and start over again as may times as you like.
Every time it is folded in half the total layer count increases geometrically. The layer count doubles with each fold.
Even though I wrote this tutorial many years ago. The general proceedings remain as valid as they did then. Cleanliness, proper layer mating, correct forge atmosphere and fluxing or a method to exclude oxidation are key factors to a good weld.