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Hardening Stainless Steel

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Thomas Gude16/01/2013 16:53:58
104 forum posts
26 photos

Hello,

I recently purchased some stainless steel (no idea what grade or composite) wax carving tools from the market. I have found these invaluable for some of the more niggly bits of various modelling tasks. However the thin flat tools often let me down by being too soft and bending.

Is there a way I can harden these by tempering and quenching? What colour would I need to get them up to? How would I go about the quenching?

wax carving.jpg

Thanks

Thom

Tony Pratt 116/01/2013 17:16:04
1190 forum posts
5 photos

Hi Thomas, generally stainless isn't hardened, if your flat tools are bending and you did manage to harden them they would most likely snap.

Tony

Terryd16/01/2013 17:25:13
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1935 forum posts
179 photos

Hi Thom,

You probably can't heat treat them, you may work harden them by planishing with a polished hammer of suitable size. You could always experiment with one of the least useful shapes.

These tools are really made for wax carving believe it or not. We used them by gently heating in a spirit flame when making wax models for investment casting, it was more a case of 'wax forming by melting' rather than a simple straight forward carving process. Therefore they didn't need to be particularly strong or hard.

Regards

Terry

HomeUse16/01/2013 17:26:49
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168 forum posts
12 photos

Hi have never found the need to harden such small tips, but have hardened stainless steel knives - Heat to cherry red and then Quench in a tank of water with a good layer of Mineral Oil floating in the top - Has worked well without re-temering.

Thomas Gude16/01/2013 17:56:34
104 forum posts
26 photos
Posted by HomeUse on 16/01/2013 17:26:49:

Hi have never found the need to harden such small tips, but have hardened stainless steel knives - Heat to cherry red and then Quench in a tank of water with a good layer of Mineral Oil floating in the top - Has worked well without re-temering.

Thanks, I will give it a go. Mineral Oil - As in engine oil?

tm

Nicholas Farr16/01/2013 18:35:54
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2410 forum posts
1188 photos

Hi Thomas, many grades of stainless steel will not harden by heating and quenching. Generally speaking if it is an austenitic stainless steel, that is, if it has little or no magnetic attraction then it will not harden by heat treatment.

Regards Nick.

David Jupp16/01/2013 18:44:42
738 forum posts
17 photos

I can't see some of the posts becuase they are obsucred by the advertising (this seems to happen irregularly on this site) so apologies if this is off beam...

There are different types of stainless (ferritic, austenic & martensitic)

300 series are probably most common - these are austenitic, they work harden like crazy - but do not quench & temper

martensitic, can be quenched and tempered - think surgical blades

ferritic - I don't have much information to hand at present !

So some stainless grades can be quench hardened, but many can only be work hardened. You can sometimes (but not totally reliably) identify austentic steels as being non-magnetic (work hardening can tip them into being magnetic...).

Stub Mandrel16/01/2013 18:53:09
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4311 forum posts
291 photos
1 articles

When I started on this curious hobby I was sold some stainless steel as silver steel. I had great fun and frustration trying to harden it.

Neil

Thomas Gude16/01/2013 18:56:57
104 forum posts
26 photos

Thanks for the posts. Not got any magnets to hand, but do at work so will check then. Bit nervous on work hardening - wont this deform the tools? Plus I don't have an anvil. Will attempting to temper them end up actually annealing them and I end up worse off?

David Jupp16/01/2013 19:21:25
738 forum posts
17 photos

Was not suggesting work hardening as a method to use (it explains why so many drills get broken in stainless) - just pointing out that 300 series steels will not harden by quenching.

If you want to harden stainless, it has to be from the correct family - if it is strongly magnetic you have a good chance it is. If weakly magnetic it's probably only workhardened austenic steel so will not quench harden.

Jens Eirik Skogstad16/01/2013 19:44:25
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395 forum posts
22 photos
Posted by Stub Mandrel on 16/01/2013 18:53:09:

When I started on this curious hobby I was sold some stainless steel as silver steel.

Neil

Hehehe, you are swindler!!!

Here is the article about hardening the stainless steel: http://www.msdspring.com/Technical/reference/17-7ph_techsummary.pdf

And the other: http://www.bssa.org.uk/topics.php?article=151

I am car mechanic and, i learned out the valves is stainless steel in some brand of car since the valve is not magnetic, no rust and very hard enough against abration in the cylinder head.

Edited By Jens Eirik Skogstad on 16/01/2013 19:51:09

Stub Mandrel16/01/2013 20:30:42
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4311 forum posts
291 photos
1 articles

Hey Jens! I was swindled, not the swindler!

Funnily Ienough I still have the stainless in several sizes and I made the valves in the pic below out of some of it last weekend! It is very free machining and doesn't work harden so perhaps I didn't do too badly.

Neil

Some more bits of engine

Jens Eirik Skogstad16/01/2013 23:02:26
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395 forum posts
22 photos

Neil, funny to see you swindled... Maybe the seller can't see difference between silver steel and stainless steel since the seller had not magnet to learn out the stainless steel will not stick to magnet or a bit weak depending on alloy in stainless steel and take a grinding test to see colour and form of the spark.

I has model petrol engine with stainless steel valves. The valves are not hardened and still in good condition. Also the valves in stainless steel running in bronze as a part in the cylinder head are not a abrasion problem.

Nice work of the engine!

Edited By Jens Eirik Skogstad on 16/01/2013 23:03:12

Edited By Jens Eirik Skogstad on 16/01/2013 23:04:58

Thomas Gude17/01/2013 09:49:18
104 forum posts
26 photos

Okay, so I just tried them against a strong magnet and there is a fair bit of attraction - it could have been more but was certainly stronger than what you get with SS mahine screws so my reckoning is it isn't austenitic. I will give the hardening a go and report back. I don't want to try this if it ends up annealing and softening the tools though, anyone have thoughts on this?

PS nice pics

Ian S C17/01/2013 10:27:24
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7468 forum posts
230 photos

As a small child,I remember watching my uncles dental technition modeling dentures in wax using similar tools, but made of plain steel, he worked with a little spirit lamp to heat the tools, he was a real artist at his work. Ian S C

HomeUse17/01/2013 10:30:22
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168 forum posts
12 photos

Hi T G - Yes Mineral Oil as in Natural Engine Oil - Not Synthetic

From what I understood as the steel passes through the oil it takes up some carbon and forms a slight case hardening - Also the Stainless I used did have a slight magnetic attraction.

Give it a try - Hope it works

MikeB

jason udall17/01/2013 10:35:13
2026 forum posts
41 photos

re hardening.

1 if heat treatment can improve the hardness then nothing lost all to gain.

2 if heat treatment cant effect temper/hardness then nothing lost...

My reading on stainless says "NOT HEAT TREATABLE"...

Surical steel .. scaples and the like (is I believe 316S11) is completely nonmagnetic* and usefully hardwink

(*non magnetic to a degree but not to MRI levels)

......but the purests will tell you SS "edges" are inferiour and don't last...scalple blades are disposable...

HomeUse17/01/2013 10:47:33
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168 forum posts
12 photos

Hi - Have trolled thro web - came up with this which is similar to my way - might add that my knives were for sea fishing **LINK**

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