blisters on damascus?

B

bill may

Joined
Jul 30, 2014
Messages
70
hello I'm trying to learn forge Damascus and I got to the point of oil quenching only to find blisters arose on the steel.
my question is what caused this? was it the type of steel, type of oil, a trapped air bubble, did I just miss something when I cleaned up the steal at the beginning?
if any one has been here before I would really like to hear what you think.
 
blisters are caused from something being trapped between two of the layers of steel in the stack and whatever is trapped is keeping the layers from welding.
 
thanks. that's kind of what I was thinking. a lot of work for a disappointing end. but that's how you learn.
 
A bad weld will come back to haunt you. It may not show on the surface, but it can blister in HT, or you can grind into it in doing the bevels. Sadly, there is no remedy....it is time to start a new billet.

When welding up a billet, set each weld and when you are satisfied with the weld.... re-weld the billet again. Do this each fold/stack. Don't draw out until you can't see the lines between the welds. If there is a dark line on the billet side, there is likely a bad weld. Grinding the surface between folds and not over-fluxing is also a key to eliminating bad welds.
 
A bad weld will come back to haunt you. It may not show on the surface, but it can blister in HT, or you can grind into it in doing the bevels. Sadly, there is no remedy....it is time to start a new billet.

When welding up a billet, set each weld and when you are satisfied with the weld.... re-weld the billet again. Do this each fold/stack. Don't draw out until you can't see the lines between the welds. If there is a dark line on the billet side, there is likely a bad weld. Grinding the surface between folds and not over-fluxing is also a key to eliminating bad welds.
 
I was wondering if I over fluxed. I was making a twist pattern and I thought maybe trapped some in the fold.
thanks for the advise it's nice to be able to ask some one questions when they pop up.
 
if you notice the blister while forging it can be "popped" with a sharp chisel then lightly fluxed and rewelded. you can also cut through the blister and restack then weld again. this is the best way to do it in my opinion but multiplies the layer count by a factor of the number of pieces being restacked, ie... if you have a 50 layer billet and the blister is a third of the way down the length of the billet you need to cut through the blister then cut the remaining bar in two again giving three more or less equal length pieces which when restacked and welded give a layer count of 150.
 
This is why I like making knives. It's not easy, that's what makes it fun. Thank you again for your advice. As a beginner, to get answers from Master Smiths is pretty cool.
Whenever I make a knife worth showing and I can figure out how to post a picture on this site, I'll show one for critique.
Bill
 
If you're setting the welds (especially the early ones) by hand, you can squeeze excess flux out by being sure to hit the center of the billet and then go toward the outside. If you had a sandwich with a lot of mayo on it, what happens if you squeeze in the middle? Yup, mayo all over your lap- but if you squeeze on the outside, the mayo stays in. Flux = mayo
 
Better yet, eliminate the flux and eliminate the danger. Contrary to popular belief, commercial flux is not necessary for forge welding. You can use a variety of other "flux" like agents, or nothing at all. If your forge gets sufficiently hot enough, (say around 2400 degrees) and you use a hydraulic press, flux is not necessary. I usually dip my billet in diesel fuel (some people use kerosene) after mig welding the ends and attaching a handle. The billet is pretty hot when it goes in the diesel. I only use a little flux on the billet to show me when the steel has reached welding temp. A light dusting is all that takes.
 
Cliff, do you just do the ends, or do you seal all the joints between layers? I've seen it done both ways.
 
why diesel? to burn out foreign materials? I've never heard of this before.
I do use a hydraulic press adapted from my wood splitter(22 ton) I also use a coal forge.
I've been thinking of getting or making a gas forge, I see the one's on e bay around $160-$200
and think that's a little pricey but then I think about the price of materials and the fact that I've never built one before and I'm not sure which way to go. it's the burner that has me most concerned about getting it right. any input on this would be appreciated - bill
 
Hydrocarbon flux (diesel) provides a thin film of hydrocarbon the protect the surface of the steel. Dry welding has been discussed here quite a bit. Dry welding works best when the mating surfaces are ground clean and as flat as possible. Then either a box is made to prevent oxidation or the seams are welded shut. No O2 means No Scale. Also if the mating surfaces are very close ie surface ground, flux or dry welding can be eliminated. But everything has to be perfect to get good welds. I have gone to 100% dry welds now. When I have a specially intricate or time consuming billet I make sure to surface grind the final weld or two. THen I am assured of 100% welds. Now temp, 2400f is not needed in dry welding. I did a test where I welded in the 1600f range. Don't recommend doing it that low but it can be done. I weld in the 2250f range. NO higher. Higher weld temps cause the muddy appearance esp in high layer count billets.
 
thank you for the info. bye the way I checked out you're website loved what I saw. if you don't mind me asking how many years did it take to reach this level of craftsmanship and did the ABS have a lot to do with this? the reason I ask is that I'm only a few hours away from the school and I've been telling my self I should sign up for some classes. thank you again for the information -bill
 
I have been forging 23 years now. The ABS has given me a lot of inspiration and desire to better my craft. You can learn in 2 weeks what years of self taught trial and error would. I recommend the school if you are able.
 
I gave my self a 2yr window saying if I'm still making knives that's were I need to go. well I've definitely been bite by the bug and I'm closing in on that time line. thanks for your response that's what hoping to hear. -bill
 
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