Hello,
I did a search on old posts, but I did not find a post that solved this, forgive me if I missed the one(s) The quick and dirty is that my welds are very weak, The long details are below:
I have been struggling with forge welds being very weak. I am welding in a gas forge (single Venturi burner, side entry 3x4 cross section about 12” long), I think the flame is very close to neutral based on the color of the flame being right on the edge of transitioning from green to blue when I adjust the choke. (maybe there is a way I can test that better?)
The weld I am working on is a faggot weld of 3/8" square bar to itself. Either bent back in a loop and scarfed or two together (ends aligned and not scarfed). Hot rolled Mild steel (whatever comes from the steel yard) I have tried this about a dozen times and usually get the same result.
I grind off the mill scale so that the steel is bare and shiny, then I heat to red and flux with borax. Then I bring up the heat until all the borax is bubbling vigorously. I would describe the color as a bright yellow. If I take a pointed piece of the mild steel and press it to the bars at this temp in the forge, it welds instantly and I can lift the piece with the pointed piece and need to twist to get it off.
I pull it out and weld it on the anvil with 3 light, quick blows and the pieces are stuck together. The anvil is very close to the forge (within 2 feet) and I make sure to waste no time. I always get them to stick.
I take a second heat and go over the weld again from the other side. I then take another welding heat and focus on blending the scarf with the pein. Next I go over one edge and blend it and then the other. By now, the two pieces look completely blended, when they heat I can see no seam and the scale forms uniformly. I sometimes forge it down again at welding heat.
Then I let it air cool to room temp and test the weld by bending it in a vice by pulling on piece away from the other. Every time the weld pops open with not much effort, maybe 10 or 15 lbs of force on a 6 in piece .
The surfaces look shiny, sometimes a small section tears out, but I can never get that level of adhesion over the entire surface. (See image of two attempts, both were loops that I bent back on themselves and then split after welding and tested
I have tried this a lot of time with varied strength of the blows, normalization cycles, using new 1045 (instead of mild) that I forge to 3/8”, forging the section down more, fluxing cold, not fluxing.
I even took out my oxypropane torch and tried it with borax and got the weld to stick, but then had the same failure in testing.
Could I have a contaminate in my flux? Is my forge more oxidizing than I think (I tried going richer, but then I struggle getting to temp)?
I really feel stuck and would really appreciate some help
Thank you,
-Josh