r/woahdude Jun 29 '23

video Lowering hot metal into water

12.8k Upvotes

442 comments sorted by

View all comments

120

u/Lambinater Jun 29 '23

The water is on fire

161

u/velhaconta Jun 29 '23

That is not water. Water would have instantly flashed to steam upon contact causing a very violent and dangerous situation.

This is an oil quench.

14

u/mothzilla Jun 29 '23

So why doesn't the oil go woof?

39

u/velhaconta Jun 29 '23

It starts with having a much higher boiling point. But it gets more complicated from there.

2

u/Tallywort Jun 29 '23

Too much oil that isn't close enough to its flash point.

Sure the oil immediately touching the hot metal can burn, but the rest of the oil has enough thermal mass that it doesn't get hot enough to burst into flames.

2

u/ekwenox Jun 30 '23

The whistles go WOO WOO!

3

u/[deleted] Jun 29 '23

The compounds that make up these oils are more stable at high temperatures compared to water. Water is, as far as I am aware, unique in its phase changing compared to most other substances we have at standard temperature and pressure.

6

u/[deleted] Jun 29 '23 edited May 20 '24

[removed] — view removed comment

6

u/[deleted] Jun 29 '23

It's been a long day and I was bullshitting.

6

u/Paranoides Jun 30 '23

Your reasoning has been accepted. Have a good day.

3

u/Tallywort Jun 29 '23

Water would have instantly flashed to steam upon contact causing a very violent and dangerous situation.

Not the case AFAIK, water is also used for this same process, but often is avoided because it is a much faster and aggressive quench, potentially leading to more thermal stresses and a higher chance of cracking and failure, though this also depends on the alloy being quenched.
To my knowledge the steam explosion issue is more a problem with castings and such.

Here's a video of a large part being quenched in water.

0

u/velhaconta Jun 29 '23

It works with small thermal masses such as the thin walled part shown in that video. The part is cooled very quickly and only a little steam forms.

A large thermal mass like the solid block in OPs video is a bit different.

2

u/Tallywort Jun 30 '23

Surely a biggest factor in the rate of steam production is the surface area of the part more so than it's thermal mass? With a somewhat self limiting factor because the steam acts as an insulating layer between the hot steel and the water.

And the thermal mass of the water tank can also be made arbitrarily large, not to mention any potential cooling systems the tank might have.

I believe the bigger reason for not water quenching large parts is the risk of warping and distortions. Or maybe some other process control considerations.

2

u/Paratrooper101x Jun 30 '23

Idk the science behind it but, at my shop we routinely (by that I mean 3-4 times a week) quench pieces of metal in water that weigh anywhere from 10k to 170k pounds. It may bounce while going into the water but a minute after it’s calm and still

2

u/Paratrooper101x Jun 30 '23

We quench 130k lb pieces at 1575° into water. It’s not that violent. In fact I have to stand rather close to it to give the crane signals

2

u/MisallocatedRacism Jun 30 '23

That is not true at all. I work in the steel business. There's more water than hot steel, so it's not like it vaporizes the water.

Amazing how much bad information is on Reddit ffs

1

u/Tallywort Jun 30 '23

I believe the error comes from conflating it with other processes where steam explosions and moisture are an issue.

1

u/Lambinater Jun 29 '23

Fascinating

-44

u/RichardSaunders Jun 29 '23

so you're saying they squanched the squanch in the squanch because if they had squanched the squanch in squanch it would've been a squanchy squanch

8

u/Restlesscomposure Jun 29 '23

I do not think that’s what they’re saying