Hardening process...

I make all batches of tools like chuck keys from EN16MT steel, they work well and last adequately.

I have been asked to make a smaller tip than normal, this time about 1/8" square and was thinking of using the same steel but hardening it after?

Is this possible in a small home-shop business, not had to harden anything until now.

The bod is 1/2" and they are made on a CNC mill vertically, using a 10mm bull-nosed end mill to give a fillet radius where the tip joins the body.

Any tips much appreciated

Thanks

Dave,

Over here in the Colonies, I usually make things like that out of O-1, which has almost 1% carbon and a small amount of other high strength alloying elements. I heat it to cherry with an acetylene torch and quench in oil. I draw it back to a straw to keep it from being brittle, letting the bulkier part go to a blue.

Jim

Google has not been helpful to de-code "EN16MT" steel into a familiar standard like SAE, ANSI. Can you help us foreigners out with a generalized grade?

Here is all i can find....

BS970: 1955 BS970: 1991 COLOUR CODE DESCRIPTION
EN16MT 606M36T blue/green Bright drawn semi freecutting manganese molybdenum steel


CHEMICAL ANALYSIS
Car 0.32 / 0.40
Sil 0.10 / 0.40
Mang 1.30 / 1.70
Phos 0.035 max
Sul 0.15 / 0.25
Moly 0.22 / 0.30


MECHANICAL PROPERTIES
Tensile Strength N/MM2 Min Rm 850 / 1000
Yield Stress N/MM2 Min Rm 700
Elongation A Min % on 5.65√SO 8
Izod Min 40
Kcv Min -
Proof Stress 0.2% N/MM2 Min 680
Brinell Hardness 248 / 302


INTERNATIONAL SPECIFICATION COMPARISON
BRITISH BS 970:1991 606M36T
BRITISH BS 970:1955 EN16MT
GERMAN DIN
FRENCH AFNOR
SWEDISH SS
AMERICAN SAE
EUROPEAN STEEL NO.
EUROPEAN STEEL NAME
EUROPEAN STANDARD


QUICK VIEW SYSTEM
MACHINEABILITY 90
WELDABILITY Not recommended
HARDENABILITY High strength up to 30mm dia
SELECTION GUIDE AND USAGE EXAMPLES As EN16T, but more suitable for repetition machining

Yes, you can harden EN16 more than the level you get with the EN16T. West Yorkshire steel has the parameters laid out.

Fot our colonial cousins, EN16 is similar to 4037 or 4042. It's used for nut and bold manufacture and similar applications.

regards
Mark

Thanks, great link.

So, its already hardened to the T state in the chart shown, is there any point in going further?

What sort of steel/treatment would allen keys be made from?

I can test this but need to make sure the little tip doesn't just twist off

Allen wrenches are mostly made from AISI 8650, hardened to mid 50s. Some are made of S2.

If the OP’s gonna heat treat just get the EN16. This stuff roughly comports to AISI/SAE 4037 but has double the manganese and about half the silicon. It’s interesting that in the T strength condition it’s a slight tick more than what we call “brake die” in the states, which has .5 carbon.

The manganese adds strength & hardenability, the silicon bumps the strength (-1/2 here) and the moly (strength, hardenabilty and toughness) is a wash between the two.

It’s a bit of a mix on how you’d want to heat treat it… You can jack it up by water hardening or oil hardening, my guess is a real heat treater would rather go oil hard since it has changes in section. Looks like cool stuff, but in a small shop not used to Q&Ting things, you prolly want to send it out to get the quality consistent.

Good luck,
Matt

Thanks guys,

sending it out is not really an option due to cost i feel, these are pretty low budget items, I just thought i might be able to expand my range a little with the smaller item.

I might do some tests with it in the T state and see how it holds up, its not a highly stressed tool just the small section makes it more delicate.

If you’re looking for forged & HT strength from bar stock you might look at Viscount 44. It’s an H13 hot work tool steel drawn to 42-46RC (machinable) and pretty much matches high end chrome vanadium heat treated tools.

It's a fair bump up from what get with the EN16T and really stable while machining.

Good luck,
Matt

Happened to harden parts myself tonight for the first time. They are O1 tool steel machined and normally sent to hardening. Price per is ridiculously cheap since 1500 parts don't cover the $100 minimum. Problem was I don't want to wait a week on test parts and pay $10 per on 10 parts occasionally.

I borrowed (permanently most likely) a Rockwell tester, bought the cheapest little kiln/oven I could find with digital programmable controller and a bucket of quench oil. Read the spec sheet and tons of web posts.

Simple as can be. Threw them in a SS bag from McMaster, programmed the preheat, final temp and soak. While that started I threw the quench oil in a steel bucket on top of a NuWave induction stove and heated to 135*.

After treat parts were 64R. Surprised it worked I tempered in a small oven and they were 61R as planned. Destruction / use test was identical to what I get from treater. Still can't believe how easy that was or how well the test came out. I planned on spending all day tomorrow, Saturday and Sunday testing. Guess I'll run what needs hardened in the morning and start the holiday weekend quenching my thirst for frosty beer instead.

It's doable in a small shop. It's not an exact science and I could have gotten 'lucky' but hard is easy if they don't need to be exact. I don't plan on running production stuff here because the electricity would probably cost $100 to do 1,500 parts, but for making test parts hard enough to use on stainless I think I'm golden.

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Sounds good, why does the quench oil need to be heated?

Dunno. Got a much more detailed book on the way, but every source species the oil should be 135 and quenching should bring the part to between 125-150 the immediately temper.

My guess is that it affects the rate of cooling of the metal. Of course the vast majority of people online giving instructions how to harden are doing it with everything from a BBQ Grill to a handheld propane torch in their backyard without any fancy purchased accessories. It seems O1 is pretty forgiving

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Did you cut the bag to drop the parts in the quench oil?

Davis In SC said:

Did you cut the bag to drop the parts in the quench oil?

Click to expand...

Yes. I tried unfolding it and dumping them but the bag was too small and too tight around them so I had to cut and dump. I fully expected the extra time to lower the hardness but it didn't. This morning I practiced using a much bigger bag that I can unfold the 'seam' with pliers and use a knife to open the end to dump them out. Test was 5 parts, this bag has 53 parts and is in the oven right now. I forgot to mention I added some brown paper in the bag to absorb the oxygen as it burns.

Test parts before and after crushed glass blasting



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Feasibility of self tempering through induction hardening

We are taken up gear manufacturing project where we have a challenge of induction hardening of teeth followed by furnace tempering. As it is requisite to do tempering immediately after induction hardening to avoid crack due to cooling stress. Our induction hardening tooth by tooth process take 3 hours time for one component. My first teeth of induction hardening will be allowed to cool for 3 hours for me to complete my entire job. What is the possibility of my first teeth or my initial teeth to develop crack before i complete my entire job.