Quote Originally Posted by DrDalton View Post
I believe “lead quenching” is used in the wire industry.

Liquid salt baths and liquid metal baths are also used for Marquenching/Martempering.

Your concern about the formation of a “vapour jacket” around the hot metal is well founded and a known problem.

That is why the hot metal should be continuously moved/agitated when quenching, as it insures that the metal remains in contact with the quench medium, as the vapour rises to the surface. Of course agitating the medium helps achieve the same result.

The search for quicker quench mediums in hopes of achieving more hardness may be misguided.

My understanding is that you only need to cool the steel just fast enough to get it through the transition zone in time, any faster does not give better results.
In fact going too fast leads to the dreaded “ping” and the breakage of the steel. By way of example if you take an oil hardening steel such as O1 and quench it in a fast medium such as water you will end up with lots of broken blades.

As for quenching speed, I don’t think there is anything faster than an agitated and saturated brine solution. Not to many steels can survive such a harsh quench, especially with the thin cross sections and stress prone shapes found in blades/razors.

Additional: This reasonable discussion (Quenching Medium - Heat Treating, general discussion - I Forge Iron) is interesting and suggests that “super quench” (as outlined here Robb Gunter) is faster then brine.


Thank you for your answer, you appear to know about the process.
I've read about marquenching and salt baths. What I'm wondering about is, metals are excellent heat conductors by their nature, so, wouldn't that result in a more uniform temperature drop to the piece of steel we'll be quenching, unlike oil/water/salts? If the piece of steel cools uniformly, no matter its speed, wouldn't that reduce greatly the formation of these cracks?
Theoretically, quenching in an alloy would be a smaller shock for the piece of steel; the liquid alloy will be a lot colder, but again, since it's an alloy, the heat transfer would be a lot faster, resulting in both a faster AND gentler quench for the whole piece. IF we achieve same or higher heat conductivity with that of iron (steel should be close to that) that would mean, we will be able to achieve maximum hardness with close to zero failure rate for our quenched edge no matter it's shape-size.

Does that make sense?

I would like to find a way to achieve hardness, for low alloy steel with carbon content close to 1%, of above 65 RC (like some Japanese razors that have showed a hardness rating of 67RC, how could they do that in an age where knowledge and technology was behind) and am searching for ways to do that. If I could reduce the failure rate, that would be a big bonus since grinding a blank, at least for me, takes days.