Crank steels
Turbo Mini Forums

Evening all,
Ive been lurking hereabouts for a while, soaking up the knowledge.
Does anyone know why cranks are made from EN40B? Im looking into a special project and EN24T looks at first glance to be a better steel, with higher tensile strength and smaller elongation. I know EN40 is a nitriding steel, but do cranks really need hardening?
EN40B:
http://www.kelvinsteels.com/spec_722m24.htm
EN24T:
http://www.kelvinsteels.com/spec_817m40.htm

cheers

Dave

Sanderson Precision
Specialists in Miniature and Micro Engineering

I think the early Turbo cranks were hardened and the later ones were not or vis versa.

The material would have been chosen depending on the calculated stresses of the crank. Other than that I cannot summise.

Own the day

the 24T is already tempered and thus has a higher strength than would be in untempered state,

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Yes, so the En24 is already heat treated, and presumably doesnt need a post 'hack into a crankshaft shape' heat treatment, that the EN40 does need to get the best from it?
I need a funny stroke, and as I have the tools in the garage (TOS mill, Harrison Lathe, J&S grinder etc) and I fancy having a go Im looking at it before buying metal / making swarf.
It will of course end up turbo'd 8-)

Dave

Sanderson Precision
Specialists in Miniature and Micro Engineering

the answer if there to see, why would you want to try machine an already heat treated steel , use something softer then bring it up to strength with heat tratment post machining .


carl

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