truck leaf spring

[lamepro]

so i have been working with an old truck leaf spring making (or trying to make) knives and other bladed objects. i have some some dabbling with quenching in different mediums. water,motor oil (new and used). i heat them up to a tangerine orange color (a bit past non magnetic) then vertically quench in one of the aforementioned. they do get hard but i was just curious what others peoples experiences have been? what works best?

[bigfootnampa]

For that type steel oil quenching is usually most effective. It is not enough just to dip your steel when you quench... you should quickly transition to a figure eight stirring motion and continue that until flames die out. Water quench will harden the steel but is far more likely to produce cracks and/or bends that degrade the usefulness of the blade or tool. In any case hard enough is hard enough... you will want to temper back the hardness anyway... so the least violent quench that will harden the steel enough is best.

[pkrankow]

I use vegetable oil, canola specifically, because I do not like the smell of motor oil. Works about the same as motor oil.
Phil

[jimmy seale]

howdy, i use non foaming hydrolic oil that i heat up to about 140f. works well for me,jimmy

[fat pete]

I use JD hydrostatic oil..lol..I got it for free and it doesnt smell as bad as used motor oil....then i heat up a rr spke to bright red...I have a wire tied around the spike and I dip it in the 3"x 3' pipe welded to a small I beam ...nice and firm standing.. I leave the spike in and then I heat up the piece and dip it in the hot oil...when I put the spike iin, there is no flame but when I put the piece in it will flame... it does get hard...I wonder how deep???
Question I have is does the temp of the oil really matter? I have some old store bought steel that comes in a paper wrap that says the oil should be 145-165 for so many mins...the steel is a specific grade...but with a spring how critical is that oil temp...
I made a lid for when it flames...

[Mainely,Bob]

For me the thing to watch with oil is the temp that it will flame up and burn.I know there`s a technical term for it but it escapes me now so I`ll call it the Fire Factor or FF for short.

I look for an oil with as high a FF as I can find that is still thin enough to work with.Right now I`m using high FF hydraulic oil because it`s(relatively) safe and I got it free.
Before that I used peanut oil for the same reasons.I went to the hydraulic oil because it had a higher FF.Once it proved to be effective I recycled the peanut oil.
The peanut oil smelled better but the safety of the hydro oil made me switch.I use an exhaust fan to pull the fumes.

They do make special quenching oils but I`ve found them to be too expensive for what I mostly use oil for which is tool making.

BTW-Larger is better(within reason) for a quench tank just like a slack tub.

[forgemaster]

The term you were looking for was flash point, quenching oil needs to have a fairly high one.

Phil

[ThomasPowers]

One of the odd things about quenching in oil is that warm oil quenches faster than cold oil. This is due to the change in viscosity so warm less viscous oil can convect the heat away faster than cold more viscous oil.

While there is a lower limit, "enough", you don't really need more unless you are planning to heat treat multiple pieces and want to keep the rise in temp of the quench medium to a minimum.

My quench tanks are vertical metal tubes holding several gallons and mounted to a stable platform so they can get knocked over and make a mess or a fire!

Don't use plastic. I know a smith trying to eke out his quenchant in a plastic bucket by tilting it on it's side for a longer blade than he normally forges.

Oil flared up, melted through the bucket and ended up burning down his shop destroying a powerhammer he had just finished restoring.

[Mainely,Bob]

Flash point,there it is!FP,not FF.
Thanks Phil.

The point about staying with a well anchored metal tank is a really good safety point Thomas.I saw a fellow set a #10 can of oil on fire and then knock it over trying to put a lid on it.Good thing it was outside and away from anything.Still made for an exciting time though.

[Jack Evers]

A somewhat different use of truck spring, but still a heat treating question so I'll leave it here. Some years ago I used truck spring to make a barstock shear, 1/4, 5/16, 3/8 thick and up to 1-1/4 width. I merely heated above magnetic and let it air cool. It lasted for years, but what would others have done?

[gearhartironwerks]

so i have been working with an old truck leaf spring making (or trying to make) knives and other bladed objects. i have some some dabbling with quenching in different mediums. water,motor oil (new and used). i heat them up to a tangerine orange color (a bit past non magnetic) then vertically quench in one of the aforementioned. they do get hard but i was just curious what others peoples experiences have been? what works best?

So, a friend who is a master at making pointy, sharp things suggests using 1 part diesel to 4 parts atf for the quench. apparently this mixture pretty much eliminates the flash factor from quenching. haven't tried the combo and am still using atf straight and thinking i should get off my lazy ass and get some diesel.

JE
Gearhart Ironwerks

[Mainely,Bob]

So, a friend who is a master at making pointy, sharp things suggests using 1 part diesel to 4 parts atf for the quench. apparently this mixture pretty much eliminates the flash factor from quenching. haven't tried the combo and am still using atf straight and thinking i should get off my lazy ass and get some diesel.

JE
Gearhart Ironwerks

I`ll start by saying I`m no expert,just another guy that`s been doing this for years.I`ve tried many things from motor oil to hydraulic fluid and also asked people who actually do this for a living and from what they told me there are 3 things to be concerned about.
First is viscosity,generally speaking the thinner the oil the quicker the quench.The viscosity of an oil and the quickness of the quench for most commonly used oils can be most easily controlled thru heat.Warm the oil and it gets thinner which allows it to quench faster.
The second concern was flash point-Simply put,how easily will the oil catch fire,how fiercely it burns and how hard will it be to put out if it does catch fire.Gasoline is not a good choice for quenching for obvious reasons.You get the picture.
The third thing to consider is the smoke/fumes coming off the quench when you use it or even when it`s just sitting there uncovered.Many feel used motor oil has a lot of bad mojo floating around in it waiting to jump out and put a choke hold on your health insurance.
You pays your money and takes your chance.
That being said I switched from fryer oil given to me by a friend in the food service industry to marine grade hydraulic fluid with a high flash point which was also given to me by a former fisherman.The hydraulic fluid(much like ATF) does an excellent job and mice have stopped trying to sacrifice themselves in my quench tank.The down side is the shop doesn`t smell as appetizing come quench time,but I am less tempted to run for a snack after quenching and have lost rather than gained weight this winter.
There`s my silver cloud.

I would think you could bypass the diesel and lower the viscosity of your quench by using straight ATF and warming it by tossing in one or two heated scraps prior to quenching the work.
I would also look at the MSDS(available on-line) for whatever quenchant you plan to use as a safety precaution.

[pkrankow]

So, a friend who is a master at making pointy, sharp things suggests using 1 part diesel to 4 parts atf for the quench. apparently this mixture pretty much eliminates the flash factor from quenching. haven't tried the combo and am still using atf straight and thinking i should get off my lazy ass and get some diesel.

JE
Gearhart Ironwerks

I would expect the diesel to have a lower flash point than the ATF, so be careful.

Phil

[MattBower]

Flash point is certainly something to take into account (I agree that straight gasoline and diesel are not smart choices for quenchants, whatever their cooling properties may be), but as long as you're following the rule of thumb of at least one gallon of quenchant per pound of steel, and starting with your oil at an appropriate temperature, you'll have to do something dumb to get it hot enough to sustain a burn. I normally monitor my oil temp with a candy thermometer. If I were doing multiple quenches in a short period of time (which would be unusual for me), I'd make sure to let the oil cool back to the appropriate temp between quenches. But a single quench really doesn't raise the temp to anywhere near a dangerous level. And I'm using Parks/Heatbath #50, which has a flash point of "only" 285 degrees F. By all means, though, use a fireproof container with a fireproof lid!

BTW, peanut oil has a pretty high flash point -- higher than most commercial quenching oils. Canola's is nearly as high.

If your leaf springs are 5160 (many are, but I don't think you can ever take that sort of thing for granted), you don't need a terribly fast oil. For 5160 you've got almost 5 seconds to get to 900 degrees F, in order to get maximum transformation to martensite. That's not too hard.

[pkrankow]

... For 5160 you've got almost 5 seconds to get to 900 degrees F, in order to get maximum transformation to martensite. ...

Where do you find information like this? This is good stuff!

Phil

[MattBower]

Er, xxxx! I just deleted this post while trying to add another one. Quick recap:

TTT diagrams. You need to miss the nose of the left-most curve on the TTT diagram. There's another type of diagram that's even better, but they're impossible to find and TTT works well enough.

Here's the one I referred to to answer this question: http://www.britishbl...h-carbon-steels Yeah, relying on stuff you find on the Internet is always a little iffy.

Note that the scale on the bottom is logarithmic (SP?). So you have just under five seconds to get to 900 F, then another five to get to 800 F, and so on. The idea is to stay to the left of the left-most curve all the way down to Ms, if you can. That usually isn't difficult as long as you miss the "nose" of the curve.

By the way, there's a very expensive book that contains a whole bunch of TTT diagrams, or you can download them individually, here, for a price: http://www.kaker.com...aisi_index.html But I normally just rely on my Google-fu.

[Nakedanvil - Grant Sarver]

PK: they're known a TTT's or "isothermal transformation curves" nowadays.

That's not too hard.

Might not be the best wording when you're talking about hardening. Maybe "That's not too difficult"?

Oop! typing while you're posting, Matt!

[pkrankow]

Thanks Matt and Grant
Phil

[MattBower]

PK: they're known a TTT's or "isothermal transformation curves" nowadays.



Might not be the best wording when you're talking about hardening. Maybe "That's not too difficult"?

Oop! typing while you're posting, Matt!

Good point! Difficult is what I meant. :)