Identifying mystery steels

Following my visit to the scrapyard and new assortment of steel, is there any way of getting a rough idea of what I've got?

One of the pieces, a 2" round bar had a bright silver appearance although with some flash rust and a polished appearance. The rest had a grey mottled finish like ordinary cold rolled steel.

You could try a spark test.

I've not found sparks work particularly well, probably because I haven't learned by sparking known metals or because the system doesn't cover the huge range of alloy steels available.

I came seriously unstuck as a beginner because workshop gremlins ensured my entire collection of scrap-metal was difficult to machine. All of it was horrible! Not surprising, because modern manufacturing selects metal to suit their design goals, and then heat-treats or plates. The result can be scrap that's downright unfriendly.

My test now is to stick a sample in the lathe and try and turn and face it. The difference between Free-cutting mild-steel and a difficult alloy is very obvious. The first cuts to a good finish without fuss. Difficult alloys are extremely hard or soft, with any combination of very tough, gritty, easily torn, grabby, crumbly or smeary. Some are just a bit tricky to find the right cutter geometry rpm, feed-rate and depth of cut. Others refuse to produce a decent finish, or rapidly blunt tools, and a few are impossible. Now I prefer buying known metal. When tempted by scrap, I dump it as soon as it proves difficult - it's not worth the trouble.

Much depends on where a scrapyard gets metal from. One serving an area full of machine shops is much more likely to have machinable metal than those taking scrap from domestic or specialist manufacturing. The latter might even be risky to cut - Magnesium, Beryllium, Cadmium etc

All my local scrapyards are hobby unfriendly. They buy metal, but don't sell to punters. Browsing in the yard is definitely not allowed - razor wire and dogs! Others are luckier. A friendly yard might have a hand-scanner to accurately identify whatever elements are in the alloy, and might be persuaded to use it, especially if the customer is a big spender!

Dave

Most of them will tell you to just "Go away" or words to that effect !

I'm afraid that getting steel of unknown specification can be a real time waster when it comes to using it. Like SOD, I do the same test of facing and turning to see if it is usable for what I want to produce.

I did come unstuck on this subject a few weeks ago when I came to make a new slitting saw arbour. I found a bit of bar in my scrap box, just over an inch in diameter and about five inches long, I had marked it up as EN3B. Set it up in the lathe, took the first cuts, lovely bright finish, swarf tight blue curls, (very hot on the hands). No, certainly not EN3B, It was part of a batch of short pieces of EN24Y used for cylinder head studs that I had acquired many years ago for a special job at home. I can turn it and drill it with care, but there was no way I was going to be able to tap a thread in it. I had just marked it with the wrong specification at some point.

Now I only buy material that I know what the specification is, saves a lot of frustration in the end, might cost more but usually worth it.

Neil

For anyone within easy distance of Macclesfield, John Swindells is a reputable dealer, willing to buy and sell.

MichaelG.

A rockwell tester is handy for sorting metal. Most of the time you don't really care what it is, as long as it is strong enough for the job. And combined with a furnace you can even harden and temper a test piece.

I've been lucky enough to work out a swaps system with my local guy - although the first load I took in (copper HW cylinder) got me on his books with ID and the usual formalities. So now if I take in, say, a radiator, he'll swap it for some mild steel bar to save writing out a cheque.

Rob

I recently heard about a set of rockwell hardness testing files, might this be the answer to selecting suitable machinable scrap steel?

A set of Tsubosan Japenese testing files can be had for approximatly £80 off ebay.

I'm not impressed by the idea. Spending £80 on a set of files may not be smart If the idea of buying scrap is to save money. An ordinary file will indicate if a metal is too hard to machine, but not much beyond that. Hardness gives a hint about steel, but is less useful on non-ferrous metals.

I know it's painful, but I recommend coughing up for metal known to be machinable. After becoming familiar with how machinable metal cuts, it's much easier to identify whether or not scrap is suitable.

Dave

I agree, unless there is a good reason use EN1A Pb, which is now known as 230M07 PB. If a supplier tells you his steel is GCQ (good commercial quality) it means he has lost the cert, or has bought in a load of unknown steel and is trying to get rid of it.

From my point of view, yes its nice to get experience with known materials. However checking steel prices for say 5"x 1" billets from renown stockists even on eBay can be eyewateringly expensive. £100's for a few kilos of stock. I would rather go to the scrapyard or local fabricator and take a chance on a careful selection of the offcuts. Preferably finding out their identification paint codes so as to get a rough idea what the materials are.

£7 for 25 kilos of flatbar, a selection of large billets and other extrusions seems a chance worth taking.