heat treating 410- Water, oil, or air quench. Temper or not?

[Gruber]

I have been air quenching with a temper around 350 degrees. I've also done some water quench at 1700 degrees with a temper at 500 degrees. I was not at all impressed with an oil quench and 400 degree temper. What have you guys who have been playing with 410 found to work?

[Baron Alcyoneus]

What problems did you find with those formulas?

[Gruber]

I like all of them, but not the oil quench- seemed soft and lifeless. Now, oils with no temper was a very lively piece, but after three very strong strikes to it while mounted to a tree with a Del Tin blade it did spring open a crack. Coolest thing too. About ten or fifteen minutes after setting it on the table; *POP.... TING* not soft sounding, but pretty violent. I thought the dog had knocked over a glass or a plate at first.
I'm wondering which method you guys prefer and why- I'm becoming partial to the water quench just because of how visceral it feels. Air quenching may be safer as far as warping goes, but it kinda takes the fun out on the other hand, if people are having just as good of results with air and 'x' temper; I'd like to know.
Thanks

[AwP]

The type of oil can make a huge difference in how it quenches. Some oils quench almost as fast as water and others are very slow. I haven't specifically worked with 410 (my HT experience is with high carbon tool steels), so I can't recommend a particular oil, but I would suggest experimenting with some you haven't tried before. Unless of course you're happy enough with the water or air quenches.

[Craig Nadler]

I was thinking for trying 410SS again so I'll be watching this thread.

The 1st time that I tried using it 12 years ago I couldn't get it to harden enough even when using a water quench. The large heat treating shops that work with it have vacuum furnaces with integrated quenches. The work piece being hardened gets quenched in place without moving. In the end I figured that sending it out to a shop with millions of dollars of heat treating equipment was the way to go.

Bodycote Thermal Processing in Laconia, NH for 410SS offers to heat treating, test, and certify the pieces for:

$77.25 setup fee
$1.63 per pound
$5 testing fee
$10 for a Certification Letter
$128.75 minimum order

Considering the recent ACL/BotN helmet failures having a certification letter stating that the item was heat treated and tested by a certified heat treating shop would seem to me to be a major selling point.

Best Regards,

Craig Nadler

[Tom B.]

I was thinking for trying 410SS again so I'll be watching this thread.

The 1st time that I tried using it 12 years ago I couldn't get it to harden enough even when using a water quench. The large heat treating shops that work with it have vacuum furnaces with integrated quenches. The work piece being hardened gets quenched in place without moving. In the end I figured that sending it out to a shop with millions of dollars of heat treating equipment was the way to go.

Bodycote Thermal Processing in Laconia, NH for 410SS offers to heat treating, test, and certify the pieces for:

$77.25 setup fee
$1.63 per pound
$5 testing fee
$10 for a Certification Letter
$128.75 minimum order

Considering the recent ACL/BotN helmet failures having a certification letter stating that the item was heat treated and tested by a certified heat treating shop would seem to me to be a major selling point.

Best Regards,

Craig Nadler

In the scheme of things that is a pretty reasonable price.
I would pay an extra $200-$300 on $2k of armour to make sure everything was heat treated perfectly.

[Tascius]

I've done a set of 410 splints quenched in transmission fluid. Not impressed. Tomorrow I'll try an air quench.

[Atlanta Armory]

Different material (4340), but we also used transmission fluid, though we were a but more concerned with surface hardness than fracture resistance (was for tripod / universal joint housings for axles). I don't remember how we tempered, but I know we did.

[Baron Alcyoneus]

Just in case you don't have the tech sheet, AK Steels has good info on various steels.

http://www.aksteel.com/pdf/markets_prod ... _Sheet.pdf

[Halberds]

I should look it up in my "Heat Treaters Guide" standard practices and procedures for steel book.

Although Alcy had a web link.
I have not much experience heat treating SS.
I have heard the 400 series heat treats better though.

What about a water/air quench, spray garden hose on the sidewalk?

[Craig Nadler]

Gruber:

I'm going to be making a COP, splinted cuissies, splinted greaves out of prehardened 301SS soon and I was thinking of making the knees, arms, pauldrons, helmet, and gauntlets out of 410SS. What kind of results have you seen with 410SS and how does hardened 410SS compare with 1050 at a Rc42 (1600F water quench and 30 minute 650F temper)?

Have you tried welding 410SS yet? I'm thinking for getting a TIG welder and ordering ER410 welding rod.

Best Regards,

Craig Nadler

[Gruber]

Hey Craig! I don't see much difference in dent resistance. Springiness is amazing though! Personally, I like the 1050 better, especially when it's blackened.

[Craig Nadler]

Hey Gruber. Did you send out the two 410SS BtoN suits to an outside heat treating shop or heat treat them yourself? Does the air quench in front of a fan result in the 1050 like dent resistance or is that with a water quench?

I was thinking that if I stick with 1050 for the knees, arms, pauldrons, helmet, and gauntlets that I might tin them this time. Bob Reed and Jeff Wasson both know of period inventories specifying tinned armour, but I'll need to get my hands on copies of the documents in case anyone at BotN 2013 challenges it.

Best Regards,

Craig Nadler

[Zanetto]

Hi Gruber,

Just a quick question. Do you find that the 410 SS that you air quench has the same dent resistance as hardened and tempered 1050? Does water quenching and tempering give you better dent resistance?

Thanks,
Rob

[Gruber]

I haven't received any negative feedback from the guys who are wearing the 410 that was air hardened- and the most recent stuff that has gone out with the water quench hasn't seen action yet. I'm waiting to hear how it held up to BotN fighting. I will swear by 1050 'till my face is blue; but so far the 410 seems to be holding well- again- only because I haven't heard anything bad yet.
I think that water quenching does make it harder only because of the more immediate slamming of molecules together. I personally think that 410's only advantage is corrosion resistance. It's springy as hell though!

[Vermillion]

Gruber,

You might try a water quench with some Epsom salts added to prevent deformation. How big is your qunechant tank? Bigger is better for maximum hardness, and and agitator helps too to keep the quenchant near the piece cool. I'm told a metal trash can, a bag of Epsom salt, and a $20 farm tank agitator from tractor supply works well.

I was remembering a 1900 degree heat and quench, with a 30 min to 1 hour temper at 400-500 degree F. But I would have to check my notes. Depends on thickness of piece too.

If you start to get distortion or cracking in your quench, you can preheat the quenchant to 70 F to 100F to get a more oil like quench reaction. Ie slower. Use a farm tank heater from Tractor Supply or Amazon.

Been playing with my Friesan Stallion Colt all winter and haven't touched my armor so it is a little fuzzy.

[Gruber]

Good call V. I'm going to try that on my next heat treating. How are you controlling your scale? I've tried anti scaling compound from ATP with mixed results. I'm trying to find something that is more reliable.

[Atlanta Armory]

Just throwing this out there, but a saltwater quench is the most aggressive achievable. Probably doesn't matter with 410 but if you are working with a more sensitive metal you may want to pre-heat the quenching fluid and a slower temper.

-Ben

[Mad Matt]

I'm doing a water quench (from the hot water tap not cold water) at 1850f and then a 45 minute temper at 675f and getting good results. You've gotta be really careful about bracing though it collapses really easily under it's own weight at temperature. It does it's best to warp going into the quench too. You do have a bit of a chance to correct warping when it comes out of the oven from the temper at the 675.

I find 1050 to be more forgiving to heat treat but the 410 isn't a whole lot worse.

[Vermillion]

Gruber, I haven't had a chance to play with the ATP yet. I hope too soon. Saw your post about your Boxer. My boxer was greeting picked on by a pair of Australian Collies in my neighborhood. So I bought him a bodyguard, a Neopolitan Mastiff !! Nothing short of a black bear messes with my dogs anymore. Heheheheeh.

Ben, yes I was suggesting the saltwater to get the best potential Hrc out of the 410 and then tempering back a little to prevent cracking as needed/desired. I can't use oil at my house so a heated saltwater is the best alternative.

I know Wades friend Tom uses bar stock tack welded to the piece build a frame to prevent deformation.

[Atlanta Armory]

Most of the metalworking I've done is in the motorsports industry, and the alloys we use are a bit more finicky and sensitive to quenching methods, so my experience is of the worst possible case. It makes sense, now that I think about it, that an aggressive quench would reduce warping, since the surface would harden and re-enforce the shape before the item had a chance to deform.

[Craig Nadler]

I just ran a test with 0.040"/19ga/1.0mm 410 Stainless Steel parts for a 5 piece knee plus a small test piece. The kiln used for heating the plates for the quenching step was a Satellite J-102 with a chamber that is 8.5" wide by 9" deep by 6.25" high. I reduced the wing fan size of the knee cop / couter so that it would fit in this kiln. The plates were heated to 1950F/1066C and quenched in water. The plates were then heated for 30 minutes to 400F/204C in a Paragon HT22D heat treating kiln with a camber that is 21" by 21" by 13.25" high.

The test piece after being quenched and before being tempered flexed about 20 to 30 degrees before breaking. It seemed clear that it was at full hardness after the quench.

After the test piece was tempered it measured a hardness around a Rc 42-43. The only way that I was able to get it to break was to clamp it in a vise and bent it 90 degrees one way, then 180 degrees the other way. I hit it with a 2 pound hammer while on an anvil maybe 10 times or so and clamped it in a vise and bent it 8 to 10 times.

This wasn't nearly as controlled a test as I would have liked, but it is a 1st step in evaluating if I want to use 410 Stainless Steel for ACL/BotN armour. My gut feeling is that the 0.040"/19ga/1.0mm 410 Stainless Steel test plate at a Rc42-43 resisted denting about the same as a 0.035"/20ga/0.9mm 0.035" 1050 plate hardened to a Rc42.

[Mad Matt]

Are you guys doing an air quench doing anything to control the quench? Ie room temperature or air circulation? I really like the idea of getting rid of the warping that happens with a water quench. Guess I'm going to have to do some testing today. Heat treating a pair of black and white gauntlets today so will do an air hardened test piece and destructive test first.

[Mad Matt]

Did a test piece air hardened without a temper. It doesn't snap easily. I had to bend it back and forth twice to get it to snap but it's not quite as dent resistant as I'd like it to be. Running the temper at 350 anyway just in case it helps.

[Mad Matt]

Ok so after tempering tested it out with a cross peen. Doesn't snap till it's been bent back and forth several times and dent resistance of 20ga is about equal to 14ga mild

So I'm definitely liking air hardening since it doesn't try to warp so much. On the downside there is more scale to clean off on the air hardened stuff than there is on the water quenched stuff.

[Craig Nadler]

Has anyone tried 350F/177C temper after a water quench? If your getting 0.075"/14ga/1.9mm mild steel like dent resistence out of 0.035"/20ga/0.9mm 410 stainless steel, then it looks like I need to try a lower temper than 400F/204C. My best guess is that my 0.040"/19ga/1.0mm 410SS test plate after being water quenched and tempered to 400F/204C had the dent resistence of 0.070"/15ga/1.8mm mild steel.

[Gruber]

I did a 350F temper on 18g 410, with a water quench on a pair of bauzzies. I was too timid to hit them, but the spring factor is AMAZING. While riveting the hinges in place I "let" the hammer "walk" a few times just to see what kind of marks I got from it and nothing that alarmed me... except the sound- it doesn't SOUND tough. I think I may be a purist They are for BoTN, so any feedback I get on them I'll share.

[Mad Matt]

Haven't tried that but it's definitely not as brittle as 1050 is right out of the water quench. So it's entirely possible it would work but can't say for sure. I've got a pair of black and white gauntlets to heat treat. I'm gonna air quench them but I can toss a test piece in with them and water quench then temper at 350 if I remember

[Signo]

Someone ever tried to give a look at spray quenching? I was thinking about it, and found on the web that is a consolidated technique that can give very good performances. In short, instead of immersing the object in a liquid medium, you expose it to a nebulized liquid, that will be water. Controlling the parameters of this nebulization could be tricky, but here it says well of it.

http://books.google.it/books?id=O_blLVM ... CH&f=false

I figure the system as a barrel filled with nozzles pointing to the center, connected to a high pressure washer. Maybe the system could work with garden sprinkler nozzles , and just a valve to regulate the water flow.

[Craig Nadler]

I just tested a plate that I heated to 1950F/1066C and water quenched, then tempered for 30 minutes at 350F/177C. The results that I got were very impressive. The dent resistance of the 0.040"/19ga/1.0mm plate seemed at least as good as 0.080"/14ga+/2.0mm mild steel if not 304 stainless steel. There did not seem to be any real problem with brittleness.

[Craig Nadler]

I just tested a plate that I heated to 1950F/1066C and water quenched, then tempered for 30 minutes at with the controller set to 300F/149C. The temperature cycled from 300F/149C to 320F/160C. The dent resistance of the 0.040"/19ga/1.0mm plate seemed at least as good as 0.109"/12ga/2.8mm 304 stainless steel. There did not seem to be any real problem with brittleness. I bent the plate up pretty good one way, then back the other way.

[Tascius]

That's impressive. I might have to take up 410 again.

[Craig Nadler]

I have some important updates to the 410 Stainless Steel heat treating tests that I've been running.

The first thing is that if I start the tempering process with a room temperature / cold kiln than the temperature controller keeps a much tighter temperature range.

I tempered a batch of plates with the temperature controller set to 300F. I started with the kiln at room temperature. The temperature range during the tempering was 298F to 308F. When the plates were tested with a steel falchion many of them cracked.

I've decided to go back to a 350F temper and to always start with a kiln at or near room temperature. A 325F temper MAY be usable, but I've decided that it is more risk than I'd care to take.

[Gaston de Clermont]

I always temper at 450 or hotter. It depends on the application, but I view cracking as a worse failure than denting.

[Craig Nadler]

At a 350F / 30 minute temper the plates can be reshaped to a fair degree to correct any warping. I'm sending some test plates to the Pride of Lions ACL event in NJ this weekend.