Soldering stainless steel

S

SlyOne

Joined
Sep 19, 2006
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163
I've made quite a few knives and I've soldered brass guards on to 440C, D2, 01 and had no trouble. I have soldered mild steel to mild steel with no problem. Right now I've made a blade of ATS34 and had it cyrogenic (deep freeze) as part of the heat treatment. I have tried several times to solder a mild steel guard to the blade and it wouldn't bond or hold. Yesterday I fluxed just the blade to see if I could "tin" the area of the tang that the guard will go and I can't even tin the tang. I am using a non-lead solder that melts at 430 degrees and the matching flux sold with the solder. This is the same solder I have used before without any trouble.
I need help on this one. I get the blade hot enough but often the solder puddles and doesn't flow into the joint but even when it does it wouldn't hold. I re-sandpaper the area and clean it up and apply flux but it just isn't bonding to the blade- sold is bonding to the guard in a normal way.
 
Gody said:
I have not tried it myself but this stuff should work on stainless:

http://usaknifemaker.com/stay-brite-solder-1-16-dia-1lb-spool.html

Good luck

Brian
Click to expand...

Does that include the flux http://usaknifemaker.com/stay-clean-soldering-flux.html?

It is very important to also be using the right flux for stainless. I used a small staybrite solder with stayclean flux kit to solder homebrew kit.

http://www.ebay.com/itm/HARRIS-STAY...196?pt=LH_DefaultDomain_0&hash=item4d08a41e5c
 
Nope, forgot about to add a link to the flux but its on the same page as the the solder. Stay Clean flux it should be. Sorry.

Brian
 
Maybe they gave you the wrong flux or solder .It should say "for stainless steel ". Make sure you clean it perfectly .Not just "clean" but "chemically clean"
The capillary action that draws the solder into the joint requires a carefully made joint .take your time. For max strength and for proper capillary action you're looking for about .002" space . The soft solder is typically 95Sn5Ag [tin silver ] It's food safe so you can get points if you fix the wife's kitchen stuff !
 
I am using Oatley lead free solder and matching flux. I've used it on the following steels- but always with a brass guard: 440C, D2, 01. I had the current blade ATS34 freeze dipped (cyrogenic) as part of the heat treatment- I don't know if that had anything to do this it. Each time I try to solder I sand paper, wash (two times I used Navy jelly as a further cleaner) and then the flux, heated the area eveny and slowly. The solder sticks fine to the mild steel guard but not the blade. I took everything apart, cleaned everything up and then tried to "tin" the blade. Applied flux to a clean area of the tang, slowly heated until the solder would melt but it just isn't bonding with the blade steel. I can't figure this one out- never had a problem before.
 
The naval jelly is possibly creating an oxide layer that's preventing the flux from working properly. After sanding just clean up with acetone and hit it with the flux.
 
Sand the area of the blade again that is going to be soldered and clean it at the very least
with acetone. Start to heat it and apply the liquid flux, keep running your solder on the joint
till it melts then wipe it off with a Q-tip. If the flux starts to turn brown its over. Will put up a
pic shortly . This is an ats-34 blade and 416ss guard. Ken.
103_0262.jpg
 
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That's a nice solder job, Ken!

I'll join the chorus about cleaning the joint well. Acetone followed by denatured alcohol may help, or you can try washing the joint area and rinsing it a couple times with dawn detergent. After the last rinse, I let it air dry or speed up the air dry with a heat gun. Even wiping it dry with a paper towel can leave crap on the surface. This usually works for me, and I've had fits myself in the past soldering stainless.
 
SlyOne said:
I am using Oatley lead free solder and matching flux. I've used it on the following steels- but always with a brass guard: 440C, D2, 01. I had the current blade ATS34 freeze dipped (cyrogenic) as part of the heat treatment- I don't know if that had anything to do this it. Each time I try to solder I sand paper, wash (two times I used Navy jelly as a further cleaner) and then the flux, heated the area eveny and slowly. The solder sticks fine to the mild steel guard but not the blade. I took everything apart, cleaned everything up and then tried to "tin" the blade. Applied flux to a clean area of the tang, slowly heated until the solder would melt but it just isn't bonding with the blade steel. I can't figure this one out- never had a problem before.
Click to expand...

Are you using the Oatley paste flux which came with the silver solder. I bought the same from lowes and it didn't work on the stainless I tried (either 316 or 304), solder just wouldn't stick, ran off like water. It says it will work for stainless but it doesn't.

When I switched to harris stayclean it worked right first time.
 
I switched to 50/50 lead/tin and a 50/50 lead/tin flux and that did the trick. Yes the Oatley flux was turning brown and running out of the joint. All this got me thinking on this. The knife was a 10" blade 1/4" thick fighting type blade and I am wondering if the heavy metal acts as a heat sink such that the flux burns off before the solder melts. IAE going with the 50/50 did the trick. I have been told about ATS34 being a great steel but I'm not so sure. I use 440C a lot and it takes a good shine. I heard D2 gave an orange peel shine but the knife I made with it came out fine and I like the steel. The 01 is great- just have to wax the blade to prevent rust.
 
As someone who solders many times a day, I'll tell you the one thing that makes most soldering attempts go wrong. This is the cause of almost all solder joint failures.

TOO MUCH HEAT

If the solder melts at 425F....then there is no need for more than about 450F in heat. Use a small cool flame, take your time and let all the parts come up to the flow point of the solder together, and when it flows BACK OFF THE HEAT!

sand well with 220 grit - you can't solder oxidized surfaces
wash off well, scrubbing with a brush - the metal need to be chemically clean
clean again with denatured alcohol - alcohol is better than acetone
dry off with a paper towel - don't use a rag, or let air dry
assemble parts without touching places to be soldered - a soldering jig to hold the parts in place under moderate pressure is a good idea
apply a small amount of flux - a little goes a long way, too much just burns up and kills the process. If the flux darkens or burns, stop and start the whole process again at step one.
heat slowly - apply even gentle heat from the opposite side of the assembly as the solder will be applied from. Usually apply heat from the blade side and apply the solder from the handle side
add a little more flux - just a drop more as the flux starts to sizzle
apply solder - very little solder is needed if the parts fit right. A good trick is to pound the solder flat into a ribbon. Most folks use five to ten times the amount of solder needed.
flow solder - as the solder starts to flow, add a little more, then use a sharp piece of brass rod to "draw' the solder along the joint.
remove heat - don't heat the assembly any hotter than the flow point of the solder. A little more heat as needed to keep the solder molten is all you want.
neutralize and clean up - Boil the assembly in some water with baking soda for 10 or twenty minutes, then clean the excess solder off with a brass scraper/graver. Make one from a piece of 1/4" round hard brass rod.
 
Thanks Stacy. That´s the best and most detailed description of how to solder I´ve ever seen. Any chance you could make it a sticky?
On the subject, I have seen some makers that recommend using a heat gun instead of a flame. Its obviously a little slower but easier to prevent overheating.

Brian
 
One thing that never gets mentioned is whether the guard heats up faster than the blade. This was a big fighting type knife 1/4" thick and I was "painting the tips of the guard and the ricasso area trying to evenly and slowly heat everything but I was wondering if it would be better just to heat the ricasso area. My thinking was that both the blade and the guard have to reach 430 degrees. The way I clamp is to put the point between wood blocks and clamp it a vise, put the guard on the tang, letting gravity hold it in place and then heat. I really don't like this set up because some flux tends to run out of the joint and down the blade.
 
Put a 1" round by 3" long coil spring over the tang and put the tang in a vice, compressing the spring just a bit. The tip of the blade is sticking up, so put a cork on it. Put just enough pressure on the guard with the spring to hold it snugly in place. Apply flux and heat from the ricasso side, and apply the solder from the tang side. You can stick the solder wire through the coils and apply it to the joint.
This prevents any drips down the blade, and draws the solder up to the ricasso. Done well, it leaves a solder line that needs virtually no cleanup.
 
Great Thread!
Stacy, you flux AFTER you assemble? Are you using a liquid or paste flux?

I've been using Stay brite with the liquid solder that comes with it, with great results...except one piece of wrought that would NOT bond- must have been contaminated, but I never did figure it out, just started over.
 
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I apply the liquid flux, and move the guard up and down a bit to break any surface tension. If everything is clean and fits right, the flux will wick right into the joint....as will the solder.
 
Sorry for the late resonce, but I always wonder how you know you've reaced the right temperature to aply the solder?
 
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