More info for steel hardenning

[Christophe Mineau]

Hi,
I read carefully this post :
Homemade Steel Tempering Method
(by the way, I'm a big fan of whatever does Derek Cohen, thanks to him)

Maybe it's a question of translation, but I have difficulties to exactly understand the terms
- quenching
- tempering
- dunking
....
Could someone help ?
Thanks,
Christophe

[kbalch]

Hi Christophe,

Quenching is simply dunking (immersing) the part in liquid (usually oil or water) to cool it.

Tempering is a heat-treating process intended to increase strength and ductility while reducing brittleness and hardness. See here:

Tempering (metallurgy) - Wikipedia, the free encyclopedia

Hope that helps!

Ken

[Christophe Mineau]

Hi Kbalch,
Got it !
With Wikipedia, I understand why it was so confusing, it's because the terms seems to be false friends between English and French.
In English : tempering is called "recuit" in French (cooked again literally)
In English : quenching is called "trempe" in French (which is literally soaking)
Tempering sounds like tremper and reading the article , I was completely lost ...
Thanks !
So to summarize :
-heat to cherry red and quench : it becomes hard but brittle
-Tempering to yellow straw (200°C/400°F) : it gives back strength, keeping hard
am I right ?

Tow questions :
-what's the difference between oil and water or salt water ?
-what about putting in a kitcheen oven while cooking a cake as suggests someone in the article's comments for tempering ?

thanks,
Christophe

[DIYer]

hi Christophe, this site might give you the info you're seeking - I Forge Iron

[kbalch]

So to summarize :
-heat to cherry red and quench : it becomes hard but brittle
-Tempering to yellow straw (200°C/400°F) : it gives back strength, keeping hard
am I right ?

Sounds right to me

Two questions :
-what's the difference between oil and water or salt water ?
-what about putting in a kitcheen oven while cooking a cake as suggests someone in the article's comments for tempering ?

- Assessing the relative merits of various quenching liquids exceeds my metalworking background. The site to which you were referred by DIYer should have lots of info on this.
- I wouldn't use the kitchen oven for tempering while baking, as the metallic compounds liberated by the process wouldn't do the cake any good. Also, if you're married (and wish to remain so), I'd keep this sort of project out of the kitchen entirely…

Ken

[Christophe Mineau]

Also, if you're married (and wish to remain so), I'd keep this sort of project out of the kitchen entirely…

Ken

Thanks for the advice Ken ! Seems to come from someone with experience

Thanks also DYier, I will check this site !

[KustomsbyKent]

Two questions :
-what's the difference between oil and water or salt water ?

thanks,
Christophe

From my experience with this, typically the top oil layer & water to quench is intended to pull the carbon atoms out of the oil and deposit them on/into the surface of the red hot metal, forming a harder layer on the outside.
The layer of oil on top of the water does not need to be much, and the water is there to quickly cool the metal. Using this method will produce a bit of a flame when it's dunked in, but as its so quick, it only flames for a split second.
I have used this method on various items around the shop and garage.

I have not used salt in the hardening process, so I can't speak intelligently on that.

Hopefully that helps!

[DIYer]

Hi Kent, how fast do you have to dunk the material being tempered, so that those carbon atoms are deposited evenly?