Grr. long cracks in oil-hardening

Cool post. :)

W1, O1, A2, D2 or an HSS drill rod? ;)

The oil is supposed to actually quench a little quicker when warm.

And consitancy of quenched parts is something I've also read as a reason to warm the oil.

I quit doing that, but I'm quenching thin knife blades so maybe I'm not a good example?

I get full hardness from un-warmed quenching oil on 3/32" thick

1095.

Why the 1 second count?

I need to find a better graph to rip-off. ;)

Depending on the alloy... that TTT graph shows a "fast one" since it's simple straight carbon steel (1080 like a cold chisel) and nothing added to slow stuff down...

Once the temperature gets below the "nose" on the graph the oil will do it's job fine. The intial quench, to get the temperature below that nose, is where water or brine is needed for certain alloys like the one shown.

If the piece is too large in diameter water won't help, it'll just crack, that's when an alloy change is needed.

Cracking can be from over heating too.

And that graph shows how important it is to get your quenching temperatures figured out. I'm still trying to do that myself! :)

Reducing my flame size has helped a bunch in that.

That slowed stuff up so it's easier to see the arrest point etc.

Sounds good to me. :)

Why a tempering oil bath tho?

Softer and cracked both? :/

(need more information like which drill rod steel)

Oooo I so want you to try to make that same tool a few more times and try different things. :)

Looks like blotches of "added" steel? :)

Those are "protected from oxygen" areas under "scale blisters" is what I've been guessing.

Just got done yesterday cleaning up and lightly-re-arching my '75 F150's leaf springs... they are covered with "looks like added steel" blotches from the heat treatment. :)

Alvin in AZ

When you say "Kingsford" do you mean charcoal briquettes?

If so, I've always been told to always forge with solid lump hardwood charcoal and never briquettes.

V

Sad, but true.

Yeah, I wish. One does what one can with what one has. :(

Just phoned the Fastenal store where I bought it. O-1.

I'd read that 140 degF was a recommended temperature. My slack tub is now a "3 lb" (2.25 lb !) coffee can. This is an improvement over my previous 1 lb can! Anyway, it seems reasonable that less viscous oil would convect better.

I've had spotty success with 1/8" thick O-1 sheet, small blades. Getting better at it. The rod under discussion is 1/4". I bought lengths of 1/8 and 3/16 at the same time. I made a couple of small pointy objects using the propane torch. One was a point for one of my shop-made marking gauges (1/8) and one was a square awl (1/8). Forged the awl to shape. Both of these small bits hardened perfectly. I even used water to quench! The aforementioned spoon gouge (3/16) hardened up just fine in a soup-can of Wesson when I re-hardened the spoon.

I didn't know at the time what alloy I had. 1095 is good for almost 5 seconds, but I don't know the "nose" time for O-1. Was just being conservative.

1. I ripped off _your_ ripped-off graph ;), and
2. I just got my eBay-used copy of MTP in the mailbox this afternoon, and
3. see my post re isothermal diagrams. :)

Yippee! "I-T diagrams" came in. Bummer! O-1 isn't even remotely represented. Carburized 1320 (1.0 C) has an A+F+C nose at 3 sec and a F+C nose at 70 sec. 1080's nose is at 5 sec. 1095 nose is at 5 sec, 1095 Modified C (1.13) is at 2 sec. I'll stand by my 1 second quench time.

Indeed? Too long, or too hot? My piddly little set-up was straining to get the nipple and contents hot. Gotta spring for some more firebricks... So I cooked for a long time. However, the rod wasn't ever red at the open end of the nipple. The rod did, however, blend into the red glow of the nipple down inside. I had allowed an inch and a half to go into a handle.

I'm just dreaming about gas until I find a local source of refractory matting. I have a notion to get one of those cylindrical charcoal starters. Wire the nipple to hang down the center, fill the cylinder and light it up. In the meantime, I have some lengths of furnace exhaust vent, 4 or 5 inch diameter...

The oil bath is there for the same reason the pizza stone is. Figure a

25 to 50 deg drop when the door opens. I have better control of the tempering temperature with these thermal buffers. Because this object was to be a burnisher, I was doing all I could to avoid oxidation damage.

O-1

Not to worry! :D This is way fun. "Ah'll be bahck."

Added from where? I've seen these warts before.

I like the "protected from oxygen" notion. I got warts on my 2" x

1/8" plane blades, on what was the top side during the heat. This rod was coated in oil (I'd put it in my oil bath to check depth) and wrapped in a half paper towel, 1) so I wouldn't drip oil all over the kitchen and 2) so there'd be combustible material in the nipple during the heat. The open end, where the warts formed, would have been exposed to oxygen. Furthermore, after the quench, the business end of the rod was mottled with black spots. The spots didn't rub off. They did come right off when the sandpaper hit the rod. Need more oxygen scavenging material in the tube. Have to find that box of activated charcoal for the fish tank...

later,

If your part got so hot that it sagged, it was overheated. To avoid the cracking you would have to normalize it to minimize internal stresses before continuing with the hardening process. Never heard of waiting before the quench.

Pete Stanaitis

--------------

Austral> Greetings,

The part never got orange. I might be wrong about the sagging, then. Maybe it was bent before I fired it, and I didn't notice. It wasn't a droop; was like ~1/32" in 7".

I think you put your finger on the problem. Will normalize a sample, see if that helps.

That's not waiting, that's getting it from the fire to the quench before it cools below ~1350F, and then when in the quench getting it down to ~400F fast so it'll turn to martensite.

Thanks for the observations.

O1 needs to get under 1100F in less than 8 seconds and under 1000F in 10 seconds and under 550F in less than 2 minutes. (page 495 4th edition Tool Steels)

Only the intial quench, the time to get the piece under about 900F is critical. You'll see where metallurgists dream of something that's as fast as brine untill it gets the steel under ~900F and then be slow like oil or even air.

"dream in one hand and shit in the other..." ;)

No need now that you've got MT&P.

Page 183 :)

Seen that. :) Don't need. :) Got 3rd and 4th editions of ASM's "Tool Steels" by Roberts and Cary. Avoid the new expensive 5th edition, it's half as thick... can hardly believe it, they took information -out- of a reference book! :/

Stand where ever you want. ;)

See page 183 and think about what that dotted line on the nose of

1095's IT (or TTT) diagram means. ;) [cracking] Too hot when all-else is right. Too severe of a quench when all-else is right.

Ripped off from MT&P page 328. :)

What you're trying to do will prob'ly be better than what I've got.

But. Sticking the steel right into the flame uses less gas and time and just about everything else.

IMO... that fancy baffle system you're trying to use, right from the start, is for later experimenting to see if you can get better results than the "easy" way.

Another handicap is the quenching oil?

I've never tried straight vegetable oil (have some rancid olive oil, I'll try it) but did use ATF at first. What I found out is-> real industrial quenching oil works better than ATF. No kidding.

They've got it worked out and additives to make it not only work better, but smoke less too.

Did use a 3 liter(?) tall-olive-oil-can and later switched to a cut-off stainless steel CokaCola can from the scrap yard.

The can size and the real quenching oil both made for better results in my case.

I'm weird (never hid that fact;) but I think of quenching's like a pitcher's windup. You pull the sucker from the fire and hit the target with no lost motion and sure as heck don't miss the quench tank... if full hardness is what you want. Otherwise you end up with a combination of pearlite and martensite.

You're a funny character. :)

I mean that in the best posible way.

Instead of doing like most people and "having to be dragged into going the extra yard" you're already on the other side of the goal. :)

The oxide layer added while drawing the temper is nothing compared to the austentizing step.

There's a decarburized layer that has to be removed unless you've protected the steel by wrapping it in stainless steel foil or other expensive measures.

It's posible that the layer instead of de-carburing slightly picks up a little carbon, either way to know what youv'e really got that layer needs to be removed.

In some cases like your burnisher a higher carbon case could be a really cool thing to have, but to make a real difference that'll take time at temperature.

But see, that's a whole nuther can of worms. :/

I leave my pocket knife blades blue colored (like a an old watch spring) when I can. That's a draw at about 650F for about 10 minutes.

Cool. :)

O1 is easy to crack. :/

Don't get it too hot and quench in un-warmed oil without hesitation.

Get it well below glowing before pulling it from the oil. Grind it and sand it, let it completely cool or even put in the frezzer, then slowly warm it until it just barily starts to turn yellow and call it good, or sand it again and "yellow it" again.

O1 done that way will be almost un-filable hard.

Betcha that'll beat your first burnisher. :)

And easier to do too. :)

You're on the far-side of the goal already! :)

Dell K Allen will get you lined up. ;)

The steel won't know if you done extra for it, only when you haven't done enough.

Exactly. ;)

Not added, just not removed from those spots, so it looks "added"?

My questions for the rest of the group is...

Will anything work to protect the surface?

If so, what have you figured out to protect the surface when "finish grinding" is to be avoided?

Alvin in AZ

BTDT when I first switched to insulated firebricks from ordinary fireplace liner-bricks. It was sooo hot and bright in there I could hardly see what was going on, next thing I knew, my O1 utility knife blade was sagging and trying to touch the bottom of the furnace. :)

It made a crummy "shop knife" ...that was made out of what was left after a "bend test". ;)

Me neither. :/

1095's IT/TTT diagram in his copy of Metallurgy Theory and Pratice will straighten that mess right-out, right-quick. :)

Alvin in AZ

The blades don't color enough to see (without real perserverence) after being drawn at (275F to) 350F for and hour.

Alvin in AZ

...

Ahhhh... Just stay under the nose. I thought I had to get all the way to M90 in the shortest time. Just get past the tip of the nose, then relax and take it slow.

...

This is a trick question, right? [For those who don't have a copy at hand, there are _two_ dashed lines on that diagram.] The leftmost line looks interpolated, like things happen too fast for the measurement technique?

...

Didn't normalize the stock beforehand.

This discussion made table 10-5, p322, grab my attention.

This _is_ "later"! :)

...

See, that's where I get my "one second." I wholly agree with your "windup" notion.

...

ah, shucks, 'tain't nuthin.

Yeah. sloppy thinking on my part.

...

Might be that I should be using W1 or 1095 instead of O1 for this application, anyway.

The hassle of the surrounding, deoxygenated tubing is worthwhile to reduce the scale. The whole oil-in-the-oven thing is for getting a reproducible temperature. I'd mentioned the pizza stone idea here a while back and figured I owed the group a real trial run.

...

Yeah, get un-fileable often. Haven't yet tried to double-temper. ...

We talkin' about steel or women? ;)

Gotcha. ...

I put together a schedule for the next experiment. I'll report when it's done, in a few days.

later,

Yep and as long as the piece's temperature doesn't stop or rise (keeps going down) more and more austenite is transforming to martensite.

"the quench" they are talking about there is quenching to lower than -300F.

Notice the graphed line starts in the lower right and goes up and to the left.

LOL :) You said it better, than I ever could! :)

Yep, it's a guess and where either dashed line really lands depends on many factors that you influence and some you don't like variations in 1095's Mn content.

That's only needed if the steel was previously forged or heat treated and so the grain may have coarsened etc.

The drill rod was provided in the best possible condition for machining and heat treating. That's part of being able to call it "O1" and not something like "1585-Modified" instead.

AISI/SAE's Tool Steel designations represent consistancy and quality.

Cool. What about it? :)

That table reminds me, I want some O7 someday. ;)

Oh. :/

"sez the guy in a big hurry" ;)

I actually pratice the "windup" a couple times before I actually heat up some metal, so there will be no delay getting the steel into the oil. You've got less than a second to get 1095 to below 1000F.

I'm wanting one fluid motion that results in a "strike;)" right in the middle of the quench tank. With no fumbling around. No delay.

I quench 1095 in un-warmed oil, cold treat it, temper at 325F and get 66+hrc.

The whole original plan was to see how good of an edge holding knife I could make, my heat treated 1095 was being compared to factory heat treated M2 at ~65hrc.

----------

I watch the steel and when I see the shadow effect from where the brighter part has gone through the arrest point, I know it's getting close to time for the quench. Just watching and waiting for the color to even out telling me it's all fully converted to austenite and ready to quench. Delay while in the fire raises the temperature and promotes coarser grain, cracks and warping. Delay getting it in the quench tank results in softer results from some pearlite formation.

All that standing around "watching grass grow" then all of a sudden like... you gotta move fast -and- sure, both.

Ok so that's overly dramatic, but there it is anyway. :)

---------

Couldn't agree with you more on that! :)

O1 is for when 1095 or W1 won't do it.

In my case O1's availability in specific thicknesses was one.

Thin, long and wide kitchen utility knives that warped to beat hell when I made them from 1/16" 1095 was another. I could have left all the grinding for after hardening and kept using the 1095. ;)

The more I -use- O1 knife blades the less I like it tho. :/

Yeah I remember the pizza stone idea and it's still a good one. :)

I believe I'm going to come up with something similar for my toaster oven. :) Been just using the steel cookie sheet that came with it.

1095, 50100-B, W1 and L6 and 8670-M all get harder than O1.

Whatever. ;)

Cool, I like stories! :)

When the huntin magazines went from true stories to "how to" articles I quit reading the dangged things. :/

Alvin in AZ

...

Tricky, but it makes sense: rate and equilibrium chemistry.

At any given temperature, it's easier to go A -> M than M -> A. Picture two vats with two one-way pipes connecting them. One pipe, MA, is bigger than the other, AM. One vat will fill up with M, one with A. We want to empty the A vat and fill the M vat. But, as the M vat gets really full and the A vat really low, even though the AM pipe is bigger, there's more M to go into the MA pipe. We get M going back to A. So, we have to close the valves to keep our M. To our good fortune, the MA valve closes a tiny bit faster than the AM valve. We keep cranking down the valves and squeeze out the very last drop of A to M.

...

OK, even if I'm a wee bit cynical about quality control in the international steel manufacturing industry. I'll look to thermal shock as a possible culprit instead of raw material quality.

1. I'm rethinking my treatment schedule, and
2. Yeah, I want some O7 too!

...

See! SEE! I told ya a second! ;) ...

Nice. Just the thing for glass-whittling...

...

I see where you went with that and it's pretty cool. :) That's how it works. A is unstable below 1330F and wants to transform back to something else.

Non-magnetic stainless steel where the austenuite (A) is stablized by so much Ni... you can hammer on the stuff and destablize some of the A and get it to transform (or decompose;) and become magnetic.

"We get M going back to A."

Prove some of that is happening and you'll be famous. ;)

Figure material quality dead last, especially when dealing with AISI/SAE designated Tool Steels.

Material choice is another matter. ;)

Cliff posted a while back that O7 and F2 are both available. I didn't respond (time restraints and never got back to it) but I've been researching buying O7 and F2 for years and years and unless they can be talked into "free samples" then it's out of reach.

One outfit advertizes selling them both on their website but when called they deny selling either one (to a peep-squeek like me!) and the other outfit has nothing set up to sell less than a truck load.

If that weren't enough, neither is sold in "sheet" form, only rounds and hex. BTW, "plate" ain't "sheet", there's a difference in thickness that, for me, might as well get hex, then slice it into "narrow" sheets. ;)

[don't want to have to re-heat that piece and coarsen its grain because I missed the friggin quench tank to first time so...;]

LOL :)

Yeah a second. ;)

The other day I drilled some 25/64" holes through some heavy 3" square tubing. How would you countersink (clean up the edges of) the other side of the holes?

My way... use a junked wornout paring knife and cut into the steel all the way around the holes.

So "steel whittling" is another use? :)

I have several of those knives and none of them have ever been given handle slabs. They have blade lengths that are about an inch, some are thin and some are thick and all of them are sharpened "flat on the stone" at least a little, to sharpen the two "back edges" too.

I'd send you some to mess with but they ain't worth sending to Oz especially since you can make your own. After all... this is a blacksmithing group. ;)

Something really cool about a knife that can cut into stuff like a hacksaw blade tooth or tap or file can.

As far as meat cutting goes the extra hard 1095 just doesn't show its real qualities there. Don't know why, guessing it has something to do with the moisture etc. HSS on the otherhand, kicks butt on meat cutting.

Extra hard 1095 is still much better than the other factory stuff for meat cutting, stainless or whatever, but when it comes to dry cutting 66+hrc 1095 acts more like a "real" cutting tool... like a file, tap or hacksaw instead of the "knife looking objects" the factories sell.

Don't just take my word for it -please-! :)

Make yourself one and see for yourself and find out what an extra hard piece of 1095 (or old file) can cut into and how cool it is to use. How cool it is to have a -real- knife for a change! :)

Alvin in AZ

In article , snipped-for-privacy@XX.com wrote: ...

I have no idea what the real products are, but any chemical reaction is reversible. Reversible in the lifetime of the universe, or in practical use, maybe no.

So with my vat analogy, maybe there are other pipes leading to perlite or something. ...

Oz? No, my handle is from rec.woodworking where a "Neander" uses hand tools instead of power tools as the "Normites" do. Australopithecus was more primitive than Neanderthalensis. "Scobis" is Latin for "sawdust." So, I'm a hand-tool woodworker who makes his own tools. I'm now in Wisconsin, but grew up in 85224 and 85941. I know your neck of the woods. ...

I have, I have. Ground a tanto-style woodcarving bench knife from one file, made the cutter for a panel gauge from the tang. Have a drop-point bench knife ground from another file.

As I write this, the oven is heating up. I'll write up the whole thing in another post, but the gist is this: Did the preheat in the pipe nipple, packed with aquarium activated charcoal. Took the rod out of the nipple so I could watch the color during the soak period. Dropped it in the veg oil and swirled the oil, not the rod, until the Schlieren disappeared. Moved it to my little foil bath, then popped that in the freezer for an hour (po' boy cryo). Put the pan with the solidified oil

• rod into the oven and turned it on to 360-ish.

You used the C word in reference to Metallurgy? :/ Good thing this ain't the metallurgy newsgroup. ;)

For sure I don't know what-all A and M can and can't do tho! :/

Get some 1080 and austenitze it then quickly cool it down to 800F and hold at 800F for 20 seconds and then quickly cool it to "room" temperature and you've got half martensite and half pearlite.

I need to rip-off a better graph that shows how you'd really end up with half bainite and half martensite there. ;)

Page 218 Fig 7-36

Notice that Mf line (martensite finish) and how they show getting below it?

Well in practice, there is no real Mf line you can get -below-.

There is a temperature limit where the return isn't worth the expense tho. Like even 5%Cr A2 doesn't get "enough" better if cooled below -120F, but for a one-up job I've been told liquid nitrogen is cheaper than dry-ice.

There is always at least a little austenite left over that quenching cooler would get more martensite and less austenite.

Fig 7-35 :)

Dell K Allen knowed;) what I just said was true, but the graphic representation was gotten from USS Corp and it's reprinted over and over again. You'll see it in every metallurgy school book even tho it's old and outdated by new knowledge.

Fig 7-36(B) is a good one (except for the line going below the "Mf" line) notice "tempered if desired". Medium carbon steels don't always need tempering after the quench. High carbon steels almost-always do need some sort of tempering.

That's why the medium to high carbon steel line is fuzzy IMO.

Because the terms low, medium and high (carbon steel) were given to us by old-time-blacksmiths not "chemists" and other egg heads.

Never read that... just figure it to be true.

That's one very real-world distinction between 1040 and 1080 steel when, with a bunch of "book learning" there's a half dozen other reasons to divide medium and low at .77%C instead of "around" .55%C.

Oh yeah... .083%C is no longer the "eutectoid" point. :/

It got revised to .80%C and then again to .77%C.

So don't let that number "bucking around" in your reading throw you, just ride it out. ;)

There's some fine print involved in the number changes that don't mean nothing as long as you know Fe+C's eutectoid point is somewhere between .83% and .77% C by weight. Mn content and other stuff moves it one way or another.

Having a chemistry background that "by weight crap" seemed pretty silly to me. There is always talk of "updating" that. After learning the "by weight numbers" I sure as heck don't want them changing it to moles, now. ;)

Are you playing with my little mind just for the fun of it? :/

Cool. :) Are you Injun or part Injun? ;)

I spent a month or so living in a tent up near Maverick one summer and another summer east of SanCarlos. My school buddie's dad was a "blade" driver and he bid on jobs near there and during the summer we'd go live with him and do whatever we wanted (we had a Honda 90 trailbike) as long as we had supper ready when he got off work. :)

Cool. :)

You ground those out without drawing the files' temper?

Cool. :)

An O1 rod, heat treated like that will be at it's -strongest- even tho, when pushed past its yeild point, it will break clean... that yeild point will be the highest that piece of steel has the offer.

Alvin in AZ

...

The "gray cobra" is the temperature and time regime where any transformation happens, right? So if the graph were extended to very low temps and really long times, would there be a cutoff, or right-pointing "nose"? If the transformation, at temps below Ac, of austenite to anything else is irreversible, we want to hold the work at low

...

Or "activity," or worse. :(

...

Nah, just another round-eye.

An artesian spring was piped to the road-cut in one place on the Maverick road. White enameled cup (with a red rim) hung from the pipe on a balin war hook. You might have seen it.

...

Very, very slowly. Much time and elbow grease on the diamond stone. The grinding wasn't so tricky back away from the edge. Did most of it with bare hands as an incentive to watch the temp.

Back to the original topic: The third rod didn't crack. I heated it slowly, right in the coals. Poked at it constantly with a telescoping magnet. Did it after dark so I could see the color easily. No fancy quench or temper. Just plopped it into the oil, stirred it around. Sanded and polished on the DP. Used 320 SiC to take off the warts then stepwise to 600x. This rod isn't as hard as the two that cracked.

No more charcoal. There is no God but Gas, and Ron Reil is its prophet. It'll take me a couple of months to accumulate the plumbing and the pricey coating stuff.

later,

"Yes" but... "almost all of it" is a more complete answer.

No, since it's never 100% complete.

No, just more of the same of that "almost all" business. :/

Not sure where you were going with that.

Below Ac1 and Ac1,3 right? (~1330F)

Theorectically it's a way-way road below that temp.

Time or temperature... one or the other will "make changes".

Was looking at Fig 7-1 P-174 and noticed right beside it on page

175...

"Austenitizing is the key to controlling hardness in quenched steels, and it also affects eventual size change and toughness. If the temperature is too low, there may be incomplete solution of the carbides and full hardness will not be attained upon quenching. If too high, large grains may develope causing brittleness or cracking during heat treatment. Steel producers generally publish data sheets showing correct austenitizing temperatures for each alloy..."

The steel will tell you when it's ready to quench. Numbers are for people without the ability to "read the steel;)" and/or have more money than me. :)

You and me, we never want to dissolve -all- the carbides. That's for industry to do (sometimes) and if the alloy has tungsten in it that'll require the same temperatures used to heat treat high speed steel for example.

O1 has just enough Cr and W in it so a guy -can- dissolve all the FeC's and the grain-size won't go crazy. The time and temperatures required to dissolve all the Cr carbides is up there with heat treating 440C or A2. Pretty bad stuff to quench O1 from.

I'm figuring you are getting the full hardness out of the O1... (because anything less would be dead soft;) I'm thinking you need to switch to W1 drill rod if you want higher hardness.

Alvin in AZ

Page 171 Fig 6-8 r = cooling in french c = heating in french "it's French, they got it backwards" ...is how I remember it. ;)

Page 180 Fig 7-4

I *DO* hope the chief domestic engineer was pleased with all of this....

There have been some domestic squabbles in our household when I have used the electric toaster over for non-food toasting jobs.....