Forge weld stress test?

[billyO]

Hello all.  I've been practicing my forge welding of billets in preparation for getting into pattern welding.  I used 4, 5" layers of 0.125 x 1" mild steel held together with 2 loops of wire wrapped 2x each that were ground and filed to get to bare steel  Took a red heat, fluxed, brought up to welding heat, and "set" (not sure if this is the right term) the weld on one side, re-fluxed, back in the fire.  Second weld heat, "set" the other side of the stack, and back into the fire (can't remember if I fluxed again, probably did, though).  3rd welding heat I worked down the length of both sides of the stack, then squared up the billet, working until a bright red-orange color.  Wire brushed, back into the fire and on the 4th heat (a good yellow), put the billet in the vice, twisted 2 full turns, then started un-twisting.  I got 1/2 turn back when I felt a "pop" that told me a weld failed (my intent).  The end result was the middle weld failed for only 3/4-1" in length about 1/16-3/32" deep near where the vice jaws were. 

 

My question:  Was this an extremely violent test of the billet (like I hoped) and if I were to have treated this stack of welds to more normal forging (more heats to draw out and shape) would this have been a successful weld?

 

thanks   

[Rich Hale]

When you forge welded you did not get the billet hot in the center. One other item I notice is youiheated til red then fluxed, At red heat steel scales. I heat until the color just begins,,,and that depends on ambient light, then I flux. If it is not warm enough the flux will not stick. You can figure this out easy.

I use twenty mule team laundry additive for flux and it helps me know when the steel is hot enough to weld. At that temp the flux will look molten. And if you are not in bright sun and the billet is not real thin. the billet will appear even colored all the way though. Mild steel takes a little more heat to weld than high carbon. Just keep it up and you will get it.

[joshua.M]

using gas or coal? if gas, let the billet "soak" in the forge and hold a near welding temp to make sure it is heated evenly, if coal, heat very very slowly

[basher]

If you are to believe what you read it would appear that forge welding is a technique that gives you a 100% strength weld.
in reality this is probably possible in near scientific situations. In the real world it will be far from the truth in any open weld situation. oxidisation, flux inclusion etc make it far more likely for the weld to fail than the parent metal.
If I remember Tilecote then figures of 70% strength for commercial quality role welding were possible (I'll check).
Hot twisting and untwisting is almost certainly going to break open a weld unless it was 100% which is extremely unlikely.
Some things will help, increasing the weld interface surface area by drawing out will increase the chance that fresh unoxidised parent material will join, it also has the potential to crack up oxides that are in the weld interface and allow clean material to join between the broken up oxide.
Temperature cycling also helps the weld strength as the grain will reform across the weld boundry as does holding at high temp to grow grain (followed of course by cycling)
If you are wanting to make damascus start using carbon steel as it behaves quite differently to mild.
good luck and all the best