Does quenching a tool head in water after reaching the tempering temperature still grant the tempering bonus?

[Jacsmac]

The purpose of the tempering temperature range being lower than the quenching range in real life is to completely avoid the phase changes associated with hardening, so dunking most recently tempered parts into water or oil won't crack or warp them. 

If the tempering temperature is reached in-game, can I skip the wait and cool down the part in water, or will the shatter chance bonus not take effect unless I air-cool it?

[MKMoose]

45 minutes ago, Jacsmac said:

If the tempering temperature is reached in-game, can I skip the wait and cool down the part in water, or will the shatter chance bonus not take effect unless I air-cool it?

Generally you will need to cool the piece in air for tempering.

On a technical level, the game requires that there is sufficient delay between the piece reaching the tempering temperature and cooling to the settled state, which may mean (I haven't verified it to be certain) that you would be able to wait until that time passes and then cool in water the rest of the way through, but either way you won't be able to cool quickly in water right away.

In the real process, slow cooling is required to more effectively relieve internal stresses in the metal and form a finer microstructure through carbon attoms diffusing more evenly throughout - cooling quickly introduces internal stresses and uneven grain (just like it does when quenching, but in that case it's considered a side effect of a desirable process), causing the piece to become more brittle. Tempering or annealing can be done in a furnace so that it's even slower than in air, often done overnight in a medieval or home forge, or sometimes taking up to a few dozen hours in some highly specialized processes.

Edited April 10 by MKMoose

[LadyWYT]

1 hour ago, Jacsmac said:

If the tempering temperature is reached in-game, can I skip the wait and cool down the part in water, or will the shatter chance bonus not take effect unless I air-cool it?

Tagging on to what @MKMoose already said, to my knowledge tempering an item in the game only counts if it cools off slowly. I don't recommend dunking it, as that can snap the workpiece.

[Jacsmac]

1 hour ago, MKMoose said:

- cooling quickly introduces internal stresses and uneven grain (just like it does when quenching, but in that case it's considered a side effect of a desirable process), causing the piece to become more brittle.

I was definitely thinking about this before posting the question, but I must have had a lower temperature range in mind than the one Vintage Story uses. A workpiece would definitely not enjoy being quenched again at 700 C.
 

Letting the item cool down for a considerable time then skipping the rest of the time using water sounds like it should work fine, as I've noticed the piece is marked as tempered by the time it reaches somewhere about 200 C in still air.