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I Forge Iron

Cracks on cutting edge


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My first post, I have looked in post and cannot find so, My first attempt at forge welding different metals to make patterned welded blade.

1st blade, spring steel drawn out, hot cut and folded and inserted a piece of 1095, welded and drawn out, hot cut and folded and inserted another piece of 1095. Hammered the bevel and shape, grind, heat treat, finish grinding and etch with Muriatic Acid. When I pulled it out the etching revealed cracks running from cutting edge toward spine.

2nd blade, 5)1" band saw blades, and 5) pieces of1095. This time I grounded the bevel instead of hammering, thinking it might give me a little better pattern. Same process as before, normalizing three times and quench. I am using canola oil without a temp gauge, but I heat another piece of mild steel and heat it up before quenching. Same results with the cracking. This blade was so hard before ht that I couldn't get a drill bit of any size to drill into the tang so I heated the tang up and hot punched it.

Sorry, no pictures.

I think it is one of two things or both. First the cooling rate of the different metals in the  quench caused the cracks or I just screwed up on the quench. I have successfully quenched the spring steel and 1095 by themselves and got a hard blade.

I don't have power hammer or press so it takes a while using arm and hammer and have another 60 layer billet of band saw blades and strapping metal ready for shaping and don't want to make the same mistake on this one.

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Sorry, I will have to do some more research, I don't know the difference. They were not visible until the acid pointed them out. I could see light all the way through but the cracks ran higher toward the spine on the surface than in the center.

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Cracks would be within the mass of a layer(s) while cold shuts would be between the layers.  Cracks may be the result of overheating, working too cold, contact quenching, etc.  Cold shuts are forge welding failures (dirt, scale, temperature, etc).  You can have both at the same time of course!

It was a trick question in a way as if you didn't know the difference you probably need to find someone to coach you through forge welding one on one. It's very hard to learn on your own and fairly easy to learn with a coach.

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I second Thomas' suggestion, find an experienced smith to show you the tricks. Forge welds are a first session skill in my shop. It's mostly a matter of following the steps and you've missed a couple while adding a couple.

In the mean time, just cut, shine up and stack the stock for the first weld. There is zero reason to draw it out first then cutting folding and welding. All that's doing is increasing the probability something will go wrong. Spring steel contains a significant % of chromium for abrasion resistance. Chrome oxidizes almost on contact with oxygen and is pretty inert making it harder to get two pieces of chrome alloy to weld so you put something ordinary in between.

Cut the desired stock the same length so you can stack it in the sequence you like. 

When you shine up the pieces have an oily rag handy, clean oil, 3 in 1 is good so is cooking oil say spray Pam. As soon as the face is shiny give it a wipe with the oily rag or spritz of Pam to prevent oxidization. Don't worry a layer of clean oil won't hurt the weld at all, it's actually good for forge welding.

Stack the shined up pieces and tack weld or wire them together, if you have a welder weld a handle to one end that's long enough you don't need tongs.

Don't wait till the billet is orange hot to flux, as soon as the flux will melt give it a dusting. This will prevent oxy from infiltrating between the layers and the oil will still be burning out scavenging any oxy in the joints. If you get flux on it soon enough oxy can NOT get in.

Bring it to welding heat and let it soak a while, the thicker the billet the longer the soak time. When the surface starts looking flickery ease off the fire to soak, you want it flickery hot all the way through. 

When you take it to the anvil move fast. Have your hammer there, the anvil clean and be ready to strike but don't lay the billet on the anvil to let the anvil draw heat off. I hold it a fraction of an inch off the fact till I've started the swing. Do NOT hit it hard, firm blows from a heavy hammer sets a weld far better. Fast hard blows can cause the layers to shear sideways or bounce killing the set. You want  almost dead blows from a heavy hammer but do NOT let the hammer rest on the billet, strike again untill you've covered the entire surface at least once.

Dust it with flux and return it to the fire to repeat the set. It won't take nearly as much soak time as the center is still pretty hot. Set it at least three times before you try forging the billet on edge.

Frosty The Lucky.

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Thanks, Frosty. I did everything you mentioned except the oil on the second blade. I cleaned, welded the ends and went straight to the fire, it welded up just fine. I think my answer is I messed up on the quench.

As far as the coach, I have looked in this state and found two on the internet, one 2.5 hours away that makes artsy stuff and one 3.5 hrs away that does classes for a few hundred bucks a day. This is a hobby and as much as I would like to spend time with someone who knows what they are doing it's just not an option right now, maybe when I retire in 3 yrs I can do that. Was just looking for some friendly advice on what may have happened. I did leave out that I reheated the blade after I had the blank formed and put in it in the vice to straighten it before grinding.

And they are cracks not cold shuts.

Thanks for the replies, both of you, I have time and all but the 1095 is free so I can go back to trial and error, I need the exercise anyway. 

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