BS1407 "Silver Steel" tempering v sheer modulus

[BCjohnny]

I've got the hardening and tempering information I need regarding the above, but have been unable to find any info regarding hardness (thus tempering temp) versus sheer modulus. Is it wise to assume a linearity?

I intend to harden and temper from different temps (probably just in the 180deg to 240deg range) as a matter of course during proving, setting up a simple bending jig to test.

The finished item will be around 200mm long, having a top section of 10mm dia, the bottom section being anywhere from 4mm up to 10mm, split roughly 50/50 in length.

Any info, or practical experience?

Cheers, in advance.

John.



"It's not always a case of learning more, but often of forgetting less"

 

[TVP]

John,

The elastic moduli (Young's modulus E, shear modulus G, and bulk modulus B) of engineering materials are essentially invariant with respect to heat treatment, so there should be no change within the temperature range you mention.

 

[mewhg]

What is 'Silver Steel'. Is there a US equivalent?

I see it mentioned a lot of dwgs sent from our home office in the UK.

 

[benta]

It's a chrome-vanadium steel with varying composition, material number is 1.2210 (European system).
I think the US term is "drill rod"?
It's normally only supplied as round precision ground rods/shafts.
It's one of the few freely available steels that is easy to harden.

Datasheet here:

http://www.kep.thyssenkrupp.com/pdf/w_2210.pdf

Benta.

 

[BCjohnny]

The critical alloying elements are approx 1.1% Carbon, 0.35% Manganese and 0.40% Chromium.

Through hardening, about 65-68 Rockwell quenched.

I would like to use as quenched (and will test in that state) but am a little wary of brittleness, hence thoughts on tempering.

Thanks for the replies so far.

John.

"It's not always a case of learning more, but often of forgetting less"

 

[benta]

The tempering graph is in the datasheet in my link.
Headline "Anlassschaubild"

Regards,

Benta.

 

[TVP]

Using any steel in the as-quenched condition is not a good idea due to the extreme brittleness of untempered martensite. Even tempering ~ 180-220 C will improve the toughness without sacrificing much in terms of hardness. Are you planning to use this as a spring?

 

[BCjohnny]

Benta....................Thanks for the graph. It follows closely the one I have, so that is one less variable.

TVP................. Perhaps asking for the shear modulus was the wrong question, for here is the enigma:

The last thing I want is for it to act like a spring, quite the contrary, as it needs to be as rigid as possible to resist deflection, the force of which approaches the shaft at anywhere between 30 and 60 degs. I was (naively?) equating hardness with the ability to resist this deflection. On the other hand I don't want it snapping either, so was trying to determine the best compromise between hardness and brittlenes.

If the lowest tempering value of 180* achieves that, then that's what I'll do. But I may test a few as quenched, just to see if they aren't prone to snapping in the enviroment they work in (the side forces have many variables, so I'll suck it and see).

For all the initial work this is the material of choice, for various reasons, so the aim is to make it as good as it gets. Long term there may be other materials used. Carbide rod is used by some, which I imagine is very brittle.

If I were making springs, austempering seems the way to go.

Cheers, John.



"It's not always a case of learning more, but often of forgetting less"