Blade heat treating. Stainless foil wrap Question?

Carl_First_Timer

Carl_First_Timer

Joined
Dec 6, 2010
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I have heat treated plenty of tooling before, and I always wrap the tools in .002" SST foil with double folds for a tight seal. I did this with the .060" 1075 Blades I am HTing, but It took far too long to unwrap the blades. By the time I was able to get them out they had lost too much heat and did not harden.

1. What techniques do you all use to keep carbon build up to a minimum?

2. If you use foil how are you wrapping the blanks for easy/quick removal?

3. Do I need to Normalize before going through the heat treat process again?
 
Maybe search around for info on anti-scale compounds used when HT'ing carbon steels? I've heard of them but don't know much about them.

I've also heard of people just snipping off one end of the SS foil pouch and letting the hot blade drop into the quenchant. That would prevent you losing your heat but watch out for splishy-splash.
 
james terrio said:
I've also heard of people just snipping off one end of the SS foil pouch and letting the hot blade drop into the quenchant. That would prevent you losing your heat but watch out for splishy-splash.
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I wanted to do that, but I was almost out of foil, so I had wrapped too close to the end. :o
 
Stainless foil wrap was designed to reduce scale on steel during the prolonged heat at high temps that stainless steel and other high alloy steel. That scaling is tough stuff and the foil helps. What is the obsession with trying to use it on every steel out there.
The HT scale on 1075 is minimal enough to remove with a few minutes of hand-sanding.
Sorry to rant on you Carl, but yours isn't the first post on this topic.
Del
 
delbert ealy said:
Stainless foil wrap was designed to reduce scale on steel during the prolonged heat at high temps that stainless steel and other high alloy steel. That scaling is tough stuff and the foil helps. What is the obsession with trying to use it on every steel out there.
The HT scale on 1075 is minimal enough to remove with a few minutes of hand-sanding.
Sorry to rant on you Carl, but yours isn't the first post on this topic.
Del
Click to expand...

Well this post is not here due to the lack of searching.

I appreciate the post, as it reinforces my thoughts on the matter. With thin stock and short soak times, I was thinking I did not need a foil wrap.

As I said I do tooling with high tolerances. Scale kills. The temps I use are higher than with simple steels, and the foil bags are much more brittle coming out of the oven. The rip right apart.

Back to the oven for me. I am very excited for my weekend project.
 
You don't need foil wrap on oil hardening steels and especially don't want to with shallow hardening ones. If you're using it on them, then you have to choose to either quench with it in the packet (a pretty large risk of uneven cooling with blades that thin) or removing it before quenching, which will likely keep you from getting it quenched under the nose.

You can put a small bit of charcoal on a piece of foil in the oven to burn off and reduce the O2 in the atmosphere if you want to reduce decarb, but it's not really a problem on 10xx steels, as Delbert already said.
 
Foil only for air hardening steels. Everything else, use anti-scale. Put some paper or WD-40 inside the foil to reduce carbon.
 
Seriously, if you get the HT right, there's basically no scale. Antiscale compound is more work than just cleaning up the knife after HT. People are trying to solve a problem that doesn't exist.
 
zaph1 said:
Foil only for air hardening steels. Everything else, use anti-scale. Put some paper or WD-40 inside the foil to reduce carbon.
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Umm, I think you don''t really want to reduce the carbon at all. The paper or WD-40 is there to add carbon.

I'm sure you meant "To reduce the de-carb".

As Nick pointed out in another thread, let those with the experience give the answers and advise. There is no crime in just reading and not posting.
 
zaph1 said:
Foil only for air hardening steels. Everything else, use anti-scale. Put some paper or WD-40 inside the foil to reduce carbon.
Click to expand...

This is my take on the subject too except I spray paint the air hardening steels with blue layout fluid to burn off trapped air inside the envelope. I like PBC from Brownells for steels other than stainless. I've had great results and zero scale. One word of caution: heat steel to around 700 to 800f for the PBC to melt and cover. Its OK to do a second coating as sometimes pits can happen from tiny uncovered areas. There is no room for scale on gun parts like hammers and triggers so I use the PBC every time.
 
Acridsaint is right. I had two customers compare results with turco - with atp 64 and with no antiscale at all. One rated the "no antiscale" as best and the other said he could see no difference between ATP641 and nothing. (Neither was impressed with Turco)

Hardness tests come out the same.

We concluded (as Kevin once mentioned) that with good time and temperature control, simple steels probably don't need any anti-scale at all.
 
I'm not getting a file to skate. It wants to, and If all my blades came out like the two best did I'd be fine with it, alas they did not. After a failed heat treat, do I need to go through any processes before attempting to Heat treat again? :(

1510 F for 10 min uniform bright orange, directly into Fast quench 11 second oil. What would you all recommend I do differently? Brine quench?
 
Carl,
Been there done that and I don't have a good answer for you but are you warming your quench oil up any? Around 140~160'F gives it a better head start than room temperature. I do my heat treating on an open wood fire so I don't have the temp control that you do but a good temperature test to to put some pickling salt (because it is close to pure NaCl with no clumping chemicals) on a piece of steel in the oven. When it melts you should be at the target temp for the steel. Also try hardening a couple of pieces of scrap and snapping then to convince yourself that it can be done and to get a good look at the grain.
Keep plugging and post pics:thumbup::D
 
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