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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: cryogenic treatments for engines.
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Sun, 14 August 2005 03:57
 
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| Lukass wrote on Sun, 14 August 2005 13:43 |
Oldcorollas,
I'm curious about the "except for gearsets" comment.
Cryo treatment is quite popular on high end steel dirtbike sprockets. Reading through the info you posted it would seem that nitriding would be the better option for this application.
Surface hardness is measured in Rockwell? I think.
Any idea on how much each method would increase this figure.
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well... aiui, cryo is used predominantly for parts which have had heat treatments, like quench/temper etc (now that i remember more correctly...) because the point of the quench is to change the austenite (metastable high temp phase) into martensite/bainite etc, which is harder....and is a diffusionless transformation pretty much.. which is why the lower temp works.. higher driving force for a solid state transformation.
car gearbox/diff parts have surface hardening treatments, and cryo DOES work for them, giving a harder more wear resistant surface layer.
if the dirtbike sprockets have a surface hardening technique involving quenching etc, then it is very likely that this is a good thing.
surface hardness is measured by a number of different methods.. many in fact.. using either a steel ball of diamond indenter.. rockwell, brinell, vickers.. micro and nano indentation.. rockwell is popular in the US which is why you hear it often (damn loud yankees  )
nitriding is also another method that can be used but....
well, it comes down to design.. if the alloy used for the part suits a temperature only hardening technique, it will be cheaper.
if the alloy has the correct composition to be able to use nitrogen hardening, then it may work out better, you can also use carbon hardening, carburising, which just increases the surface carbon content of the steel, making for better quenching treatments 
my guess is that the metallurgy for the sprockets and their surface hardening techiques are pretty well established, and cryo was the next step.. as opposed to reinventing the sprocket...
as for which is harder/more wear resistant.. it totally depends on the base alloy... and i don't really know off the top of my head...
Cya, Stewart
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| | Subject | Poster | Date |
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cryogenic treatments for engines.
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frontspinner | Sat, 13 August 2005 09:36 |
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Re: cryogenic treatments for engines.
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draven | Sat, 13 August 2005 09:49 |
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Re: cryogenic treatments for engines.
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frontspinner | Sat, 13 August 2005 09:54 |
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Re: cryogenic treatments for engines.
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Rallystanza | Sat, 13 August 2005 09:59 |
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Re: cryogenic treatments for engines.
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oldcorollas | Sat, 13 August 2005 11:24 |
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Re: cryogenic treatments for engines.
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oldcorollas | Sat, 13 August 2005 11:12 |
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Re: cryogenic treatments for engines.
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frontspinner | Sun, 14 August 2005 00:53 |
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Re: cryogenic treatments for engines.
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Lukass | Sun, 14 August 2005 03:43 |
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Re: cryogenic treatments for engines.
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oldcorollas | Sun, 14 August 2005 03:57 |
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Re: cryogenic treatments for engines.
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draven | Sun, 14 August 2005 04:29 |
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Re: cryogenic treatments for engines.
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oldcorollas | Sun, 14 August 2005 04:39 |
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Re: cryogenic treatments for engines.
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Lukass | Sun, 14 August 2005 04:47 |
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Re: cryogenic treatments for engines.
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oldcorollas | Sun, 14 August 2005 04:58 |
