Properties of “Key Steel”

[TomfileryParticipant @tomfilery]

Query re strength ,machinability, etc.

[TomfileryParticipant @tomfilery]

Hi,

I have been given a quantity of what I was told is "key steel" (as in keying pulleys to shafts). The rectangular/ square material is clearly that (and was in packets declaring it as such) in a variety of odd sizes. Does anyone know whether this is likely to just be accurately sized mild steel, or something harder/ stronger? If only mild steel, I'll just use it as stock, but wouldn't really want to waste something more specialised.

The round stock I was given looks to me to be silver steel (drill rod) with a ground finish and in 13 inch lengths. Is there any other type of steel which comes in those lengths anyone is aware of?

Much of the metal has been stored in a damp atmosphere and exhibits some small degree of pitting – though I could still use it for 16mm rolling stock axles, etc.

If anyone has any ideas about the likely composition, or machinability of the material, I'd appreciate your views. I haven't had the chance to try machining any of it myself yet

Regards Tom

[Anonymous]

Key steel is normally equivalent to EN8, ie, a medium carbon un-alloyed steel that is tougher and stronger than mild steel, but still fairly easy to machine.

Regards,

Andrew

[Ian S CParticipant @iansc]

The key steel will cut easily with a hacksaw, and easily worked with a file. With some of the machinery I work with, it has 3/8" key ways, the broach used on the sprokets, and pulleys is warn, and cuts narrow, and sometimes the keyway in the shaft is also a bit tight, but a few strokes with a file soon fixes that. It does become a problem when (as has happened a few times) the key in the shaft is not on center. Ian S C

[TomfileryParticipant @tomfilery]

Gents,

Many thanks for your responses.

Have either of you come across ground round steel rod in 13 inch lengths which wasn't silver steel?

Regards Tom

[David LittlewoodParticipant @davidlittlewood51847]

Tom,

Two things you might possibly mistake for silver steel: some stainless steels might have a ground finish (test with magnet – most but not all SS will be non-ferromagnetic, or only very slightly so); and PGMS (precision ground mild steel). However, both of these normally come in longer lengths than 13" (unless it has been cut of course).

A spark test on a grinder may be the easiest way to tell them apart (look it up). Some silver steel has "Stubbs" stamped on one end (they are, or used to be, the main maker in this country). Be aware however that is is also avalable in 39" lengths, so seeing a cut length more than 13" is not conclusive proof it isn't silver steel.

PGMS would normally arrive in the hobby trade in 2' lengths (about as long as convenient for posting and storing). It is significantly cheaper than silver steel, and is much to be recommended over it when you just want precise diameter material such as axles.

David

Edited By David Littlewood on 04/07/2012 11:27:44

[TomfileryParticipant @tomfilery]

David,

Many thanks.

I had realised that it might be PGMS and that it could be chopped from longer stock, but I don't think so. I suspect it is silver steel – though I was only going to use it for axles.

Regards Tom

[WeldsolParticipant @weldsol]

Hi Tom why not cut a short bit off the round bar heat it to cherry then quench if you can't touch it with a file it's very likely to be silver steel

Paul

[TomfileryParticipant @tomfilery]

Weldsol,

That had occurred to me, I just haven't got around to it yet.

Many thanks for taking the trouble to respond.

Regards Tom

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