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fixing weld flaws


mseronde
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Hey all,

 

I first want to say that I did try to do some searchin before posting, and I apologize if this is a duplicate question...

 

 

I have been working on a bit of damascus using aldo's 1095 and 15n20. I have had a few little weld flaws throughout the process, largely due to my novice and heat.. ( I think)

 

I am up to my final layer count, and am drawing it out to thickness, and am finding a few little flaws here and there. Other than attempting to brush them out, flux em, bring to heat and try to re-weld, are there any tips for fixing?

 

I foolishly didn't snap any pictures this morning... but the flaws are on the edge of the billit, hopefully not going too deep. It looks as though a few layers are are splitting away from the majority of the billit.

 

Does soaking it in something make any sense before trying to re-weld those areas?

 

Or simply grind em out, if possible, and hope they are not too deep?

 

 

Thanks much

 

Michael

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You'll always have shallow delaminations on the edges/surface. It's nothing to worry about. The will probably grind out. If you had a weld flaw through the entire billet, you'd probably have noticed a color difference as the steel starts to cool under the hammer. If it has stayed a uniform color, you probably have a solid weld.

 

As you move to more advanced patterns, you start to anticipate how much grinding you'll have to do to on the finished billet, and accommodate for it with added thickness.

 

For example, when doing a multi-bar with twisted rods, you'll end up with some pretty deep cold shuts on the surface of the twists. This is pretty inevitable based on the geometry of the bar as it is consolidated. I don't go thinner than 3/8" on a twiste/mulit-bar so I can grind them out.

 

Luck!

 

Dave

 

-----------------------------------------------

"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly; who errs and comes short again and again; because there is not effort without error and shortcomings; but who does actually strive to do the deed; who knows the great enthusiasm, the great devotion, who spends himself in a worthy cause, who at the best knows in the end the triumph of high achievement and who at the worst, if he fails, at least he fails while daring greatly." -- Theodore Roosevelt

http://stephensforge.com

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Thank you Dave for your response!

 

 

I ground out the edges, and it looked solid all the way around. I couldnt see any separations at all.

 

I began forging it out again, and along the edges, layers opened up again ! It is totally confusing me because while heating, everything looked super solid, no color differentiation. But then as I gently worked on the edges, maintly just to straighten things out - there was some splitting...

 

I am thinking that I am not getting it hot enough ? can working the billet too cool cause previously welded layers to come apart?

 

Thanks all

 

Michael

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Michael, it sounds like the layers in question were never welded up if they keep coming apart. Experience has taught me that you usually cannot get flux into these areas to succesfully weld them up again as there is usually some crud in there from the failed weld. If its a blister then it can be ground out.

I was teaching pattern welding to someone at the weekend and I had a billet seem to just jump apart about 5 layers in on a 14 layer billet. No real idea why so I just chucked it away and started a fresh and thats with 20 odd years pattern welding experience.

 

Mick.

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Hope no one minds...having a bit of experience this..

 

I suspect improper heat when welding..sounds like you got what I call a "sweat" weld ..ie, one that sticks but just barely. Not at the right temp for the weld surfaces to totally adhere to each other. A simple way to correct this is to get it up to what you think is a proper weld temp and then wait another 15 to 20 seconds..more of you are doing multiple layers like I do for a first weld (I weld anywhere from 35 to 100 pieces in the faggot on my first weld). Use a "minimal" amount of flux and soak the piece through.

 

You may also be experiencing weld shear but with the 10XX series and the 15N20 I would not expect that to be the case unless you are working a bit on the cooler end of forging range. Take the heat up a bit and see if that helps..

 

JPH

 

Another idea crossed my feeble mind..you may want to try a liquid flux soak in super saturate boric acid solution..let dry and then heat and apply additional flux for welding,,

Edited by JPH

If you wish to know the price of freedom..Visit a Veteran's Hospital...I am humbled by their sacrifice... 

Why is it when the Mighty Thor throws his hammer he is dispensing Justice and fighting Evil..BUT..when I throw my hammer I wind up in a mandatory 16 week anger management course??</p>

I came into this world naked, screaming and covered in someone else's blood...I have no problem going out the same way...

 

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Michael:

 

Mick and Jim have a ton and a half of experience pattern welding, so go with their advice for sure.

 

If you're experiencing the delam that you describe, I suspect you're working the steel too cold or--as Jim points out--you have a "sweat" weld.

 

I believe (JPH/Mick, correct me if I'm wrong here), but a sweat weld is usually the result of insufficient pressure applied to the billet when setting the weld (also possibly because of insufficient heat). Weld strength is a complex amalgamation of reactions, but the pressure applied to the layers is a significant part of the process. If you're setting the weld by hand and not with a hydraulic press or a power hammer, you can get tacky welds that look solid but aren't really stuck together.

 

When you set your weld with a hand hammer, start in the middle and tap your way toward the edges, working the flux out as you go. Keep the heat up at the yellow/welding temp, and do at least 3 welding heats with steadily increasing power behind your hammer blows on each heat. Turn the billet on edge and hammer on it after the third welding pass. If the weld is weak it will start to delam at this point. If it's solid it'll stay together and you can begin to draw it out for folding.

 

Luck!

 

Dave

-----------------------------------------------

"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood, who strives valiantly; who errs and comes short again and again; because there is not effort without error and shortcomings; but who does actually strive to do the deed; who knows the great enthusiasm, the great devotion, who spends himself in a worthy cause, who at the best knows in the end the triumph of high achievement and who at the worst, if he fails, at least he fails while daring greatly." -- Theodore Roosevelt

http://stephensforge.com

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I like to think of forge welding using a venn diagram. three circles over lapping in the middle is a solid weld, one circle is a clean surface/ inert atmosphere one is close contact and the third is the energy state . theses three conditions must be present, in this kind of a weld and we can create and manipulate theses conditions using heat, pressure, and flux. any one of the conditions can overcome weakness in the others up to a point. heat and pressure are the two that are easiest to manipulate, this is why it is recommended to weld at higher temps. how ever if you are using a large power hammer or press welding at cooler temps is possible, welding at cooler temps is also possible if the two surfaces are very flat, well fit and and clean. when I am having trouble getting a weld to stick I refer back to this in my head and adjust one or two variables. that normally will rectify the problem... and if not I throw it in the corner of the shop and never speak of it again . :)

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Hey Gents

 

I really appreciate your input!

 

I went and got a couple fire bricks to close up my forge, just leaving a few inches in the front door. I let my forge run for a long time to get up to temp, and after doing some filing, fluxing, and cleaning (as I was able), I brought it up to what I really believe was welding temp.

 

I did this three times, to be sure things got good and hot, and pressed together well. I use a 3lb hammer, and was gentle at first, and increased pressure in the 2nd and 3 pass....

 

The result?

It seem to be solid once again.

 

I continued to draw things out, working only at a good bright red/orange. When hammering on the edges, while being fairly gentle, it doesn't seem like anything is coming unstuck. (fingers crossed, and all the wood has been knocked upon)

 

I am almost at the length, and thickness I want before I take it to the grinder - so we shall see!

 

 

On a side note, JPH - when you mention a super saturate boric acid - what kind of ratio would you suggest? I have seen locally various types of cockroach insecticide that is 99% boric acid, is that the stuff? or should I order it?

 

Again, thanks for everyones help!

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Another little hint on increasing weld success. After you set your weld, brush, re-flux, and put the billet back into the forge. Then, soak it for 5-10 minutes at welding temp. The theory on this is that after the weld, the soak allows grain colonies to grow across the weld boundary, which helps to sort of "lock" things together. This really helps to up the overall success rates of welds in my experience.

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Ditto what Deker said. And I suspect JPH's supersaturated solution is just that. Boil some water and add boric acid until it won't dissolve any more. Let cool, and anything you dip in it will be coated in a film of boric acid. I have never tried it, but the theory is sound.

 

Edit: the reason Deker's idea works because of the nature of solid state diffusion bonding, aka forge welding. Metal atoms bond by sharing their electron clouds. The more energy you can pump into that bond, whether heat, pressure, cleanliness, or time, the more perfect the bond. Allowing grain growth across the boundary only increases cohesion on the macro level as well. It has been demonstrated to be possible to make a forge weld at room temperature under a vacuum and pressure provided the surfaces are truly clean and flat. Heat helps us who work in an atmosphere with less-than-perfectly-flat surfaces. Gets the electrons all excited, you see. Edited by Alan Longmire

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