HC taught me a lesson

[kube60]

So I don't have a ton of experience working with HC steel even though I eventually want to learn to make knives. Anyway, I have always heard how brittle hc can get when quenched in water but I didn't totally believe it. Come on, like glass? Really?

Anyway, I found a source for hay rake teeth that sells them to me for ten bucks for a dozen. I was going to make some bbq tools this morning and while I hated to waste such good steel on something like that, it's the perfect size and I'm out of regular stock in the same size.

The first step I took was to straighten it out in the forge. I figured I would leave it long and just work the end so I could use the rest as a handle. Once it was straight, I stuck it in my slack tub to make it cool enough to hang onto. I heated up the end and started pounded when I suddenly felt something give. It was the whole section behind where I was holding it. It broke into 3 pieces when it hit the concrete.

Just thought you might get a laugh out of my mistake.

The morning wasn't a total loss though. Completed my first forge weld. I have to admit that it didn't weld all the way through but when I cut off the end everything still held together so I consider it a success.

[Wesley Chambers]

Im glad you were able to learned this lesson without injury, it could have been a much more dangerously painful experience!

[Frosty]

It's more like ceramic than glass but close enough. It could've been worse, you might not've figured out what happened. Sounds like you're doing fine to me.

Frosty the Lucky.

[Alec.S]

once i thought it wsnt true.... so, i hardened a bit of coil spring set it on the anvil and hit it with a hammer......... a huge sound as fragments hit the wall!!!!!

[MattBower]

Heck, who needs to hit it? A while back I dropped a piece of orange hot leaf spring into the slack bucket and it came out all spiderwebbed.

[Larry H]

Who needs to hit it is right !!!, years ago i spent 7 hours forging a beautiful slate tool for a friend of mine , hardened it and turned around to get a temper heat and knocked it against the anvil by accident. half fell to the floor, the other half flew across the shop being closely followed by expletives

[SoCal Dave]

What went wrong? Was it quenching it in water, or working it at the wrong temperature?

[pkrankow]

There is simply a very risky time when steel is hardened, but not tempered. You can be doing everything correct and still have a break! Care must be taken, and it is recommended that you do not delay between hardening and initial tempering in the heat treat process.

I had _all_ my class heat treat projects fracture when I was in class. Happily failure of the part was not a failing grade, although I did have to re-do them. The second try worked, and I was being assisted by the lab aide, who did know what he was doing. I did nothing different from my classmates yet there were very few other failures in the class.

Phil

[cold cold steel]

knife forgings should be annealed, then hardened and tempered, especially steels with a lot of carbon

[MattBower]

Annealing doesn't really set up the ideal structure for hardening. You want a few normalizing steps between the two.

What went wrong? Was it quenching it in water, or working it at the wrong temperature?

I have the impression that hay rake tines are in the 1090ish range. Water is a risky quench for high carbon steel even if everything is done properly. Just sticking it in the slack tub, unprepared and without being sure it's at a proper temperature for hardening, has a high probability of ending badly. You can't treat high carbon like mild steel. Unless I'm trying to harden it, I don't quench high carbon until it's lost all color. (And I mean all color when I stick it up in the shade of the hood over the forge.) That's slight overkill, but it prevents problems.

[Sweany]

Hay rake tines are usually in the 1090,1095 range.

here's a discussion on the heat treat.

http://www.bladeforums.com/forums/showthread.php?t=379832

[ThomasPowers]

I usually don't keep water *close* to the anvil/forge too many times an HC piece has done it's utmost to seek out any water for the sheer joy of self destruction! All I use it for is to cool down tools and ends I'm holding in my hand---and so way under hardening temps.

Most stuff get a "desert normalizing" just toss it out onto the dirt.

For hardening I have both brine and oil tanks that have lids on them when not actively in use.

The old half whiskey barrel full of water was great for zilch carbon wrought iron but is an active hazard when forging modern materials!