Another noob question: quenching

C

cybrok

Joined
Aug 7, 2005
Messages
4,741
Hi guys

Sorry again for the newbie question.

What is the difference of using oil or water for quenching. I know one will cool the steel faster than the other so it will change the was steel arranges, but can someone translate this in a practical way? How will the result be different?
 
Different steels harden at different rates.The time it takes for the Austenite to convert to Martensite is different for each steel type,depending on the elements in the alloy.The quench has to be matched to get the best results.The speed of quench is - Brine,Water,Oil,Air. (fast to slow)
The temptation is to just use the fastest quench on everything.That would maybe work if all you quenched was shallow hardening steel like the W series or 1095. O-1, however, would crack and warp if cooled that fast (and so would many 1095 and W-1 blades).The best solution for a new maker is to use a good commercial oil like Heatbath's, Park's AAA.it is a little slower than Park's #50,but will do most any steel you are likely to use.After a while you will want some #50 ,too. AAA is made for quenching tool steel,and has accelerate added to speed up the quench.
Metallurgy is an exciting science.It pays to know what is happening to the blade when it heats up and cools down.That way you can make the most from your steel.
Lots of metallurgy info and HT info at, www.knifehow.com .
Stacy
 
New way to ask:

As a beginner, why should I buy oil instead of just taking water?

And for the science thing, I'll take a material class this fall. Lot of steel in this one :)
 
It is a mistake to quench in water, at least that is what I have been told for a long time by makers using O steels and quenching. Trust the pros and get some quenching oil. While I think a lot of oils will work, I would never risk water.
 
It's good practice to use a quench that is fast enough to get full hardness but not any faster since a faster quench risks cracking ......BTW we talk about the phases of quenching , the first being the creation of a vapor layer as the ~1600 F steel hits the quenchant. Yesterday I was discussing automobile rally problems .One in PA has a creek to cross just before the finish line .If the brakes are hot [they can get red hot] they may crack as they hit the cold water, but if they are very hot a vapor layer is formed protecting the disk !.... The rate of cooling of water is higher at room temperature but many warm the water to lessen risk of cracking.
 
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