Identifying different steels

Is there a visual or physical "touchstone" for identifying metals - specifically iron. In other words when you pick up a scrap piece of metal from say, a scrapyard, how do you know what it is - carbon steel, alloy steel, stainless steel, silver steel to name just a few

This may be one of those "you learn from experience" questions but I thought I'd ask anyway.

Colin,

Spark Testing is a good start.

MichaelG.

Thanks Michael - I would never have thought of that. Had a look at the Wikipedia entry for spark testing - the diagrams shown look more like they have come out of a floral arrangement text book - but great ides - thanks again.

The easy but unfeasibly expensive answer is to use an 'XRF Analyser' like e.g. this one - some scrapyards may even have one or an equivalent model, to identify incoming material. But you'd have to ask VERY nicely to get them to point it at your random length of scrap...

A (good) toolmaker told me that if it rusts fast in rainwater (few hours) then it's low carbon/mild steel. The higher the carbon (and other) content the less it rusts. Said toolmake sorted his scrap by said method before weighing it in.

Not a basis for a coding system, but a good rule of thumb in a scrapyard! The less rust the more expensive the material (also to carry a grinder around with you for a spark test can be a challenge)

I have a simple system like mark, look at a cut end, if dull at mild steel end the shinier it gets then it is more carbon and gets tougher ending in stainless.

Martin P

Type spark test into youtube, plenty of real life demo's, better than any picture or description.

Mike

Another way to get an idea what unknown steel is to turn it in the lathe,preferably with a HSS bit, the harder /tougher it is to machine the more carbon and other alloys will be present in the steel,but if you must buy from a scrapyard do not use the unknown steel to make parts which if stressed and break could cause injury e.g. a spindle for a motor cycle wheel,

Small file will give an idea of hardness ( easier than grinder), magnet for non-magnetic stainless. Best way is try to decide what it had been used for, eg. a bolt is likely to be a HT steel.

An old boy at the place I served my apprenticeship would pick up a piece of steel, sniff it and confidently declare it to be EN32 (or EN2, EN8 etc depending on the day)

I think I believed him at the time.

Bill D

An old boy at the place I served my apprenticeship would pick up a piece of steel, sniff it and confidently declare it to be EN32 (or EN2, EN8 etc depending on the day)

I think I believed him at the time.

Bill did he send you to the stores for a long weight (wait) aswell tee hee.

Jesse