Greater heat transfer? We always wanted to slow down the heat transfer by using a thick brine (salt water) to prevent cracking. Parts of the crank are pretty massive and you can have quite a difference in outer temperature as opposed to the core temperature, which induces cracking. I'm assuming that oil and air hardening steels were not available in 1928.
Terry
Quote:
Originally Posted by MikeK
Chris,
Thank you for the additions. I do disagree with your statement #1. Although quenching is also done in case hardening treatments, the Ford process as stated does not, in any way produce any case as it does not specify any previous treatment to diffuse carbon or nitrogen into the matrix surface. No type of quench can do that. The caustic is specified simply because it has a heat transfer rate much greater than plain water. 10% caustic potash (KOH) has a 1.38 rate, 10% sodium hydroxide (NaOH) has a 2.06 rate. This is done to ensure through hardening with the relatively low alloy steel Ford used. The quench function is to rapidly form Martensitic structure from austenite before excess carbon has time to diffuse out and form cementite (Fe3C).
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