Flame Hardening

Hi

Does any body know anything about Flame Hardening mild steel if so how good is it for small parts of valve gear on 5"g models.

Stan

Hi Stan
You can only case harden mild steel .
Nobby

Stan, you can flame harden with oxy acetylene using a carburising flame but the skin is very thin, a few microns. Set the flame to oxygen week I.e. With a long centre cone, this means the carbon fuel gas is not being fully consumed thus an excess of carbon in the flame, heat the part and keep at bright cherry red for a while, several mins, then quench in water. Might work with oxy propane but never tried this . The surface will be toughened rather than glass hard but nevertheless more wear resistant.

Not a very efficient way to harden and as I said the surface is VERY thin, best way is as Nobby says to case harden with Kasnit or similar.

I know nothing of steam valves but if you want them hardened why not make them of a suitable hardening steel, EN8 or EN9 the latter hardens easier and harder but you will need to temper them as well.

Regards John

For a short while I worked for a blacksmith and he showed me how to case hardening with acetylene. You start of with no oxygen at all, which coats the steel in black soot, then you use oxygen to heat the steel to red heat, then a repeat coating of the soot and heat to red. Do this tree or four times, then quench after the last heating. Seems that the soot is pure carbon and the heating soaks into the surface. Useful to know, but I always use Kasnit!!!

Mick, more or less same thing, I was shown to use a small amount of oxygen which in turn does depost soot on the work. I'll try your method next time I have occasion to do something but in either case the hardened surface wil be extremely thin.

Hi

Thank you all for your reply when I served my time in the late 50s we had a blacksmith who gave us a file to drill a hole in alongside his already drilled hole. After several attempts and several blunted drills he showed us how it was done, he heated to red and buried it in a box of Lime for a couple of days after that he drilled a hole re heated and buried it in a box of soot and it became a file again. I think I will use a hardening compound as suggested but I don't think you can still buy Kasnit !

Thanks again Stan

Stan...

....but I don't think you can still buy Kasnit... check this out

**LINK**

George

Not genuine USA Kasenit, somebody has just left a metatag so that your search ends on their ad! I thought genuine Kasenit was no longer made or available.

Hi All

No I bought some of that Beta 1 from EBay but it didn't work for me but I don't think Kasenit is made any more because the EU banned it for containing Arsenic I think

Stan

For reference: The archived MSDS for Kasenit can be found here.

... It's probably the Cyanide that worried the EU.

MichaelG.

Although I believe that Kasenit claims that the Cyanide as used in their compounds is non toxic, I'v still got about half a tin of it, had that for around 20 years, so at that rate it might see me out.

Ian S C

The subject of cyanide in Kasenit (and probably other case hardening compounds) has been dealt with here before.

The cyanide is probably Potassium Ferricyanide which gives up its carbon to be absorbed into the steel along with the carbon already present in the case hardening compound. By itself Potassium Ferricyanide is not toxic but will produce hydrogen cyanide, very poisonous, with a strong acid.

The label on later Kasenit tins, such as the one on my shelf, clearly states that product is "non-poisonous".

JA

Edited By JA on 18/02/2015 10:40:30

Edited By JA on 18/02/2015 10:41:20

.

For what it's worth [?]

The MSDS states the ingredient to be Sodium Ferrocyanide

Edit: and apparently, that's a food additive !!

Do we have a Chemist who could advise ?

MichaelG.

Edited By Michael Gilligan on 18/02/2015 11:28:03

The MSDS mentions evolution of trace HCN in use and makes recommendations regarding ventilation.

It's all down to quantity. Heat up a spoonful of sodium ferrocyanide and it will give off a small amount of cyanide and carbon monoxide. Heat up a spoonful of table salt and I suspect the amount given off will be comparable to what you get from eating a cherry.

Neil