Heated steel in fireplace. Whats it do?

S

SanitySource

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Mar 20, 2008
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Today I took an old knife blade tang off a swith and wesson dagger (boot) and heated it up and down a couple times in my fire place. This took longer then i expected.
But basically i heated it until it got red hot and then put it in water and then heated it up real hot and then put it in ice water.

Just playing around, with intentions that it might make the crappy (420j ?) steel a bit better?

Does anyone know what this ACTUALLY did to the steel?
 
Yes.... you probably put either a whole bunch of tiny fractures in it, or some big cracks. :)

Or, at best, you made the crappy 420 steel blade more crappy. ;)

Sorry, but that's the truth. ASSuming it had a decent heat-treat on it (all things considered) getting it that hot is way hotter than its tempering temp, so you took all the hardness right out of it. If it was really just red hot, then you weren't at an austenizing heat, so you didn't have the steel in solution prior to quenching it.

I'm not trying to be mean here, but this is akin to running over a geo-metro with a D10 CAT and hoping you made it a faster car.
 
lmao hahaha oh my i really messed it up :) hah, it was fun :P

but im trying to understand this. So if i got it hotter then the actual heat treatment that was put onto the blade in the first place then it would get hotter?

and is the water a good idea in any situation?
 
In defense of the CAT, if the geo-metro got stuck in the treads and dragged along with it... it might actually go faster!

In short, you just ruined the heat treat of a previously usable knife
 
Water and brine are often used to harden steels with low carbon contents. It's very exciting to see if you have a blade after you have quenched the blade in water or brine.

Doubtful you got the steel hot enough in your fireplace to get to heat treat temps, most likely you lowered the RC of the blade by tempering at a higher temperature than the original tempering.

Course I could be totally wrong because I've never messed with stainless cept as guard/bolster material.

BTW, Nick, how do you really feel about it? ;)
 
My posts in the last few minutes do seem a little harsh... sorry. And I HAVE had my coffee too ;) :D

I should have said that what you did sounds like something I would have done (and still do in other scenarios).

MOST factory made knives are done in air hardening steels these days. For a simple stainless like that, the steel is put in a controlled temp/atmosphere furnace and brought up to its austenizing heat (or austenitizing if you look in some of the books I own). It's soaked at temp to get the steel in solution, and then the steel is cooled in air (there are many ways to speed this up, but water is not one of them).

Water is a very agressive quench medium. Putting a hot piece of steel with carbon in it into water is a very easy way to crack the steel. IF you know what you're doing and have an accurate/controllable heat source, THEN you can successfully (most of the time) quench knife steel in water. And that's a big, huge, fat IF. :)

I can understand why you did what you did... You've heard enough to know that steel needs to get hot and then be cooled quickly to harden it. The problem is there is SOOOO much more to it than that.

Wanting to experiment and understand how things work is a GREAT thing. So is doing a little reading first ;) :D
 
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no no , not harsh at all. i knew i was probably messing it up. its a crappy little piece of steel that sits around.

thats good information , thanks everyone. But like you suggested Nick, i should do some reading first.
Can anyone recomend a good link or place i can read on how to properly heat treat steel?
 
If it was 420 stainless, then all you did was ruin the HT. It has to get up to 1900+ degrees to re-austenitize and be held there for about 20-30 minutes. The 1000-1300 you heated it did nothing good.
Stacy
 
i tested to see some of its properties so i put 3/4 of tip into clamp and with pliers i bent the tang more than 180 degrees before it snapped. so i probably decreased the hardness for sure
 
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