Salt water quenching?

[Jacob s]

About salt water quenching, how does that act on the metal as in terms of hardness, does it make it brittle by cooling too rapidly or does it make it harder than normal water quenching?

[matt87]

It's a faster quench than water all other things being equal (quenchant temperature, amount etc.). It is too fast for some steels, just as water is too fast for some steels, or oil for others still. For some steels though it can be just the ticket, e.g. quenching mild steel fullers, or railroad-spike knives.

[ThomasPowers]

For very low carbon steels it has no effect at all.

For medium Carbon steels it will make them harder than an oil quench will

For high carbon and many high alloy steels it will cause them to crack or shatter when quenched

Brittlness is pretty much a direct link with hardness---you get one you get the other. Tempering after hardening is used to trade off some of the hardness for less brittleness.

[CurlyGeorge]

So, matt87, you are saying that a salt quench would be good on RR spike knives? I have made some, but never hardened or tempered them. I'm not big into bladesmithing. So I have a lot to learn on that frontier.

[Frosty]

Not much, RR spikes are too low carbon to harden.

Frosty

[tantrum86]

if you can find spikes that are marked with hc on the head you will be better off as they contain more carbon and will harden slightly i use a brine solution to harden them and then i simply leave them at full hardness.OH and remember rr spikes taken from tracks is illegal but they can be purchased very cheaply

[CurlyGeorge]

Thanks, Frosty and tantrum86. I have a can, bigger than a 5 gal bucket, of new spikes that I bought at an auction, a few years ago. They are marked HC. But I don't know what I'm gonna do with that many. I know that's enough to last me at least several lifetimes.