Case Hardening

[not done it yetParticipant @notdoneityet]

If it has been open to air (oxygen), while at red heat, it will be like charcoal – after being used on the barbeque.

Edited By not done it yet on 30/01/2020 10:56:42

[SillyOldDufferModerator @sillyoldduffer]

Posted by ChrisB on 09/01/2020 09:44:57:

I emailed a local supplier and enquired about EN8 keysteel, and they quoted back for Bright mild steel. Is BMS a generic term for various grades of steel?

Some suppliers see it that way. Steel from some vendors goes entirely to structural trades rather than machinists. Although these chaps sell 'steel', they may not stock anything out of the ordinary or recognise any type of steel outside their usual remit. (There are over 2000 different steels available, many of them specialised…)

If a local stockist can't supply what you want try a bigger outfit, or the Internet, or one of the Model Engineering suppliers.

'BMS' is a low carbon steel, heated and rolled to be reasonably flat and fairly accurately dimensioned with clean edges. It's a structural steel, where being finished saves time and effort when building frameworks etc. Black steel is pretty much the same stuff, but it's left covered in black scale, has poorly defined edges, and only approximate dimensions. Being cheaper, it's used in place of Bright when appearance doesn't matter. Rolling makes Bright slightly stronger and tougher than Black, but Bright is more likely to be internally stressed such that it bends when cut. Mild steels, like BMS and Black, are very common because they're cheap, moderately strong, and easily sawn, drilled and welded. Soft and bendy, no good for knives or springs, can't be heat hardened, and not as tough as a high-carbon steel like EN8. It machines reasonably well, but EN1A is distinctly friendlier, and leaded better again. If a specification calls for EN8, mild-steel isn't a good alternative.

Dave

 

 

Edited By SillyOldDuffer on 30/01/2020 12:17:15

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