New thread (newbie)

Charly the Bastard posted this reply to my earlier questions.
"Auto petro products usually have metallic soaps to reduce foaming,
and these can contaminate the work at quench temps. 5160, which is what most leaf springs are made of, will go to Rockwell 61-63 full hard. Draw in oven at 375 F for two hours and allow to cool in still air to ambient; Rockwell 55-57 final hardness."
"Cool in still air". Is this the same as allowing to cool in a bucket of wood ash ? Does one have to use the kitchen oven to get the 375 for 2 hours? Isn't 375 sort of hard to get and maintain in a forge ? I take it that this 'draw and cool' is after the oil quench and is the last heat related act..
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I use an electric toaster oven with an oven thermometer inside. It works quite well for small pieces.
Eide

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Same here. :)
I had and used two Taylor thermometers one coiled bi-metal and one mercury. They read the same, so finally settled on the mercury one and bolted it to the rack.
What are you using to austenitize the steel? Are you using "the magnet method"? Are you quenching in "quenching oil" or what? Eide, where you at?
How to draw the temper on my pocket knife springs to ~650F was a puzzle for a while until I realized "stuff begins to glow at 750F in the dark".
So, at night I placed the fresh quenched and sanded pocket knife springs on the "burner coil" of the electric stove, turned on the stove, turned out all the lights and when the coil barily started to glow, I shut off the stove and turned on the lights and whatched the "colors run". :) (later realized, if the dial is set just-right, the stove will turn itself off, as soon as it begins to glow;)
Works like a champ and after they get that pretty "old watch spring" blue color pick them off the stove, cool them down, sand them white again and give them a second draw.
I had one, made from O1, break on me so I went to drawing them twice. I re-drew one-half of that broken spring again and it tested-ok the second time. YMMV
Anybody on here read that crazy method in the Brownell's catalog about burning oil away with the fresh-quenched-spring in it? Not saying it won't work (don't know, but figure it does) it's just who wants to mess with that? (even if you lived out in the middle of nowhere with no neighbors, BTDT, and still didn't like the idea)
Alvin in AZ
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I have, but it's too ackward. I just go by color. I've never been able to see the "shadow" that everyone talks about, but my stuff seems to come out just fine.

I quench in peanut oil. Whenever I hear of friends deep frying a turkey I try and get the oil. I fried my own this year for Thanksgiving so I have a fresh 3 gallons.

I'm near Providence, RI.

I've done that with my peanut oil. Peanut oil smokes at about 450F and catches fire around 600F. I don't know the exact number, but it has worked for springs.
I just looked up an MSDS of peanut oil: http://www.jtbaker.com/msds/englishhtml/p0229.htm It says the flash point is 540F degrees and the autoignition temperature is 829F. Whatever that means.
How about your methods?
Eide in RI :)
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If you can't see the shadow, you can't see the shadow. BTDT too.
I guess the trick is to heat it up as slow as you can? <shrug>
I recently went down from two 3/4" to two 1/2" propane flames, just screwed in a couple 1/2" reducer bushings (with their own screens).
http://www.panix.com/~alvinj/burner.jpg
http://www.panix.com/~alvinj/burnerhead.jpg
Resorted to having to have the "sliding air control" all the way closed and adjust the gas to match that low air flow.
I believe that's improved my heat treating.

For sure that's got to smell better than my "real" quenching oil. :) The toaster oven is now for tempering-only since it smells funny.

Cool, thanks. :)
"Gadsden Purchase boy" here. ;) Even went to work for the Sufferin Pacific RR. :)

Using peanut oil wouldn't be such a problem as what I was picturing. I believe they even mention (used?) motor oil.

Yeah. All we need to know is what temperature the liquid gets to while the surface of the oil is burning. The oil's boiling point would prob'ly do it.

"arrest point method" is a phrase I started. :)
I thought "look for the shadow" was mine too but later re-read Boye and found a reference to "a shadowy look". :/
Since my knife making is -all about- edge holding, I'm after the hardest steel I can get away with.
A cold treatment directly from the quench tank (careful not to let the steel's temperature stop going down). A measly -5F in the freezer compartment of the refrigerator will make a whopping difference in hardness... "with no change in toughness" -ASM
1095 goes from filable to absolutley un-filable.
1095 blade clamped in the vise, up-close, a new Nicholson file with enough pressure to flatten all the teeth that slide over the knife blade's corner. Not a test I want to repeat often. ;)
Taps, files and hacksaw blade teeth are that way, why not knives? :)
---------------------- My latest recipe:
I use the arrest point method watching for the shadow to form in the center areas and thicker sections,
quench in quenching oil as soon as the color evens-out, (a helper wipes it off and takes it to the freezer while I heat the next piece, when I got a helper;)
after a 1/2 hour in the freezer for the last piece, wash off the oil with soap and water and put in an extra-wide junk aluminum skillet and boil them for 1/2 hour then, put them back into the freezer for 1/2 hour (or hours if needs be)
then draw in a toaster oven for an hour at... 325-335F for 1095 340-350F for O1 275-285F for 8670-M (used circular saw blade steel)
The tempering temperatures are at the peak of each steel's tortional impact test maximums.
--------------------
http://www.panix.com/~alvinj/graph1095.jpg
Notice the hardness shows about 64hrc? (minimum) That's what the cold treatment does, it "kicks" the retained austenite around;) and gets it to transform to martensite before the first temper (210F). Then I kick-it-again, by boiling and again, by re-cooling to -5F and only then, temper at about 325F.
Springs are placed in the freezer, washed and boiled with the blades, no reason to handle them separately before I'm ready to sand and temper them. The springs are sanded white and drawn on the electric stove (in the dark, drawn to about 650F) re-sand and repeat the ~650F draw.
No real reason to cold treat springs because the retained austenite transforms to secondary martensite or secondary bainite when heated above 425F anyway.
With a cold treatment my parts tested... 1095 drawn at 325-335F tested 66+hrc. 01 tested at 64+hrc. 8670-M tested at 66hrc. 1095 springs were 46-48hrc. O1 springs were 50-52hrc.
Eide, are you sorry you asked about my methods? ;)
"if you talk to someone that's not into your hobby, and you don't sound completely whacko to them, then you're not into your hobby very far" ;)
Had a non-railroader neighbor whose hobby was railroading. He sounded completely whacko to me at the time. :)
Alvin in AZ ps- had a subsitute chemistry teacher named Eide once, last class that day, he spent a couple hours with me, filling the board with equations, figuring out the gas-pressure exerted inside a 5 gallon bucket by my firecracker, best case senario = 800 atmoshperes :) we backed it down and figured ~500 atmospheres, later it turned out, the 500 we settled on, is about the same as the inside of a 30-06 cartridge :) pps- guess "how high" the can would go (when placed upside-down over that size of firecracker ;) ppps- anyone? ;)
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snipped-for-privacy@XX.com wrote:

What did the can weigh? How much area did the 'front' present to the wind? Was there any taper in the sides of the can, if so, how much and in what direction, diverging or converging? I'll get out my high speed aerodynamics book...
Charly
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<snipped all on-topic stuff;>

In an "instant" there was at least 500 calculated atmoshperes of pressure inside an ordinary steel 5 gallon bucket (that's about the same as the chamber pressure of a 30-06 cartridge (50,000 c.u.p.) (most of that is from superheated air) the way I remember it, the bucket still had its metal handle and plastic handle cover, it was a nice, like-new, freshly emptied 5 gallon bucket (black roof coating).
The firecracker was about 3" in diameter and 4" long, hard cardboard tube with 1/2" walls and 1/2" plywood end plugs glued in place with Elmer's. ;)
That was the late 60's and up'til then 5 times as big of a firecracker as I'd ever made. The smaller ones are more fun (no kidding on that) and was almost 20 years later before I made one anywhere near that big and it was double that size. Again it's been another 20 years and don't see any good reason to ever make anything bigger than the "best ones" (they have about a 1" long 1" diameter powder chamber).
I'll quit messing with you... ;)
A firecracker with a 1x1 powder chamber is about 1+1/2" in diameter and 3" long and everytime I show someone new, I make them guess "how do you think it'll go" (5 gallon steel bucket) to get them to work on a "picture" in their head. :)
Guesses have ranged from 3 feet to 60 feet and most in the 10 to 30 feet range. I'm not sure who's more correct the 3 feet or 60 feet since the 1"x1" chamber-size-firecracker blows the can to smitherenes. Pieces shower/filter down, some over 200 feet away.
"lot more energy in that stuff than you thought huh? :)" "Wanna live in the middle east? ;)" ...are my usual smart-ass comments... :/
Somehow a car bombing on the news takes on new meaning for them after that. As it should've all along, I guess?
When you switch from cardboard+wood as the casing to metal, you're switching from a firecracker to a bomb. With low explosives inside the casing, cardboard actually makes a better/stronger "bang" in my experience. The metal ones just aren't worth the risk especially considering they are basically a waste of powder compared to what can be done -much- safer with cardboard and wood and the same amount of powder.
Metal is too stretchy or something. You end up with mostly big hunks of metal. With the cardboard "when you work it out" and "get it right" you end up with "mouse nest" (cardboard fuzz).
Another favorite of everyone that sees it is, the "pressure cooker lid" it goes up 100 feet and then looks as if it gets another boost from another firecracker (because of expectations I figure). It goes-up-top-up and finally ;) when it gets as high as it'as going to go, flips over and starts-down-bottom-up (for a while).
It's hilarious! :)
"how high do you think it'll go?" is my favorite question while showing someone the object and the firecracker. :)
Anyway, "Mr Eide" stayed after class and helped me work out the pressure since that happened to be the chemistry class subject. :)
I showed Mr Eide a piece of the bucket the next day, it was less than 3/4sqi, it flittered down right in front of us, so was the first piece picked up and I saved it. :)
Not too long after that my dear brother and stepfather cleaned-out the shed, that little piece of bucket and a bunch of other really cool stuff, went to the dump, I had receits for most of my chemicals and some other stuff and made 'em pay me. They kicked and screamed but I told them "turn about is fair play :)" -"and I have a friggin pickup [you sorry bastards ;]"-
They paid. :)
Aaaa... sweet-high-school-memories huh? ;)
"Eide, as in, sodium chlro-IDE" was his introduction in class LOL :)
Eide in RI... bet you're related to him suppose? Mr Eide's son was a geologist I met him later in Bowie AZ and we talked about his (dead) dad.
Alvin in AZ
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Good stories, sounds like you had some fun, as a kid I always dreamed of opening up my own fireworks shop.

Well, my family pronounces it like, "can I see your ID." Not too many of us Eides are related it seems. I know there is a town in Norway called Eide (ay-duh), and our family name was different when my Great Grandfather came to the States. We don't know why it was changed to Eide, but it could've been where he was from.
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<a lot snipped>
Wow, thanks for your process. I mostly use W1 and O1 because that's what I have a lot of. I'm not sure of all you were saying, but your knives are tough and not brittle? Do you thinks this process would work with the O1 and W1? (I mostly make woodworking tools and have the occasional need to make extra tough/hard tools for working with very tough/hard wood like Live Oak.)
Is this your process?: Quench, freeze, boil, freeze, temper. (with wiping/cleaning between.) Can you clarify what the boiling does?
(I saw after reading again that you state 340-350F for O1)
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What shapes/thickness you got in W1? :)
Used non-carbide tipped circular saw blades are 8670-modified unless it's an Oldham and they are 1069. Not sure when they switched away from L6 to 8670-M. That's for me to learn yet. Some careful, future spark testing might be my only clue whether I've ever even had any "real L6" saw blades.

http://www.panix.com/~alvinj/graph1095.jpg
The words tough and brittle are so abused that they don't mean much by themselves. The peak on the torsional impact test is where the steel is at its strongest but when it fails it will show a brittle failure. For the usual definition of tough (not break)... my knives are -not- tough! ;)
The edge is strong and for the most part will cut into things the way a tap cuts into metal to form threads. The knives I make aren't for everything, could be thought of, to be only good for one thing, cutting. :) That's the way I see them.

Yeah the peak for 1095 and W1 is 325-335F and the peak for O1 shifts to 350F. As you can see 25F can make a big difference.
L6 and 8670's peak is around 275F and starts dropping at 300F.

I don't know. :/ ...you experiment and tell me. :)
Thickness and edge angle and "who's doing what" are such big influences that, even if I did know anything about that at all, I wouldn't know where to start anyway. Sorry. :/
"I read a metallurgy book" -alvin

Not sure if it does anything other than clean off the quenching oil.;)
The idea is to "kick the retained austenite around" and get it to "un-stabilize" and transform into some more martensite.
The transformation is mostly while the steel is cooling so I'm giving it a chance to cool again by bringing it up to 210F and back down to -5F again. The raising of the temperature stabilizes some of the retained austenite tho. :/
Something you won't see very many places is the fact that high carbon steel like 1095 will actually get harder than "as quenched" when drawn at 210F for a 1/2 hour. It's a legitimate tempering draw that toughens the steel quite a bit from "as quenched" -and- it's harder both. No kidding on that. :) I wonder if they do files that way. :)
That extra hardness created by the 210F draw prob'ly doesn't survive as an effect after it's drawn above 265F and -for sure- doesn't survive (have a lasting effect) above 425F where the retained austenite transforms to secondary (temper created) bainite or secondary martensite anyway.
Theoretically and practically, the cold treatment's gain in hardness tho, lasts throughout the entire process right up to, say a 425F draw. The cold treatment makes a real change in the microstructure.
Anyway, all I can say is, try it and see how it turns out?
And then tell us? ;)
Alvin in AZ
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Alvin,
Thanks for all of your feedback. I will definitely try your methods with my next batch of tools and let everyone know how they came out.
(I have W1 in round and square; 1/2", 3/4" and 1")
Eide ----- Original Message ----- From: snipped-for-privacy@XX.com Newsgroups: alt.crafts.blacksmithing,rec.knives Sent: Tuesday, December 13, 2005 1:57 PM Subject: Re: New thread (newbie)
> Wow, thanks for your process. I mostly use W1 and O1 because > that's what I have a lot of.
What shapes/thickness you got in W1? :)
Used non-carbide tipped circular saw blades are 8670-modified unless it's an Oldham and they are 1069. Not sure when they switched away from L6 to 8670-M. That's for me to learn yet. Some careful, future spark testing might be my only clue whether I've ever even had any "real L6" saw blades.
> ...your knives are tough and not brittle?
http://www.panix.com/~alvinj/graph1095.jpg
The words tough and brittle are so abused that they don't mean much by themselves. The peak on the torsional impact test is where the steel is at its strongest but when it fails it will show a brittle failure. For the usual definition of tough (not break)... my knives are -not- tough! ;)
The edge is strong and for the most part will cut into things the way a tap cuts into metal to form threads. The knives I make aren't for everything, could be thought of, to be only good for one thing, cutting. :) That's the way I see them.
> (I saw after reading again that you state 340-350F for O1)
Yeah the peak for 1095 and W1 is 325-335F and the peak for O1 shifts to 350F. As you can see 25F can make a big difference.
L6 and 8670's peak is around 275F and starts dropping at 300F.
> Do you thinks this process would work with the O1 and W1? (I > mostly make woodworking tools and have the occasional need to make > extra tough/hard tools for working with very tough/hard wood like > Live Oak.)
I don't know. :/ ...you experiment and tell me. :)
Thickness and edge angle and "who's doing what" are such big influences that, even if I did know anything about that at all, I wouldn't know where to start anyway. Sorry. :/
"I read a metallurgy book" -alvin
> Is this your process?: > [austenitize using "the arrest point method"], > Quench [in quenching oil], > [cool to -5F], > boil [draw the temper at 210F], > [cool again to -5F], > temper [to the steel's peak torsional toughness temperature]
> Can you clarify what the boiling does?
Not sure if it does anything other than clean off the quenching oil.;)
The idea is to "kick the retained austenite around" and get it to "un-stabilize" and transform into some more martensite.
The transformation is mostly while the steel is cooling so I'm giving it a chance to cool again by bringing it up to 210F and back down to -5F again. The raising of the temperature stabilizes some of the retained austenite tho. :/
Something you won't see very many places is the fact that high carbon steel like 1095 will actually get harder than "as quenched" when drawn at 210F for a 1/2 hour. It's a legitimate tempering draw that toughens the steel quite a bit from "as quenched" -and- it's harder both. No kidding on that. :) I wonder if they do files that way. :)
That extra hardness created by the 210F draw prob'ly doesn't survive as an effect after it's drawn above 265F and -for sure- doesn't survive (have a lasting effect) above 425F where the retained austenite transforms to secondary (temper created) bainite or secondary martensite anyway.
Theoretically and practically, the cold treatment's gain in hardness tho, lasts throughout the entire process right up to, say a 425F draw. The cold treatment makes a real change in the microstructure.
Anyway, all I can say is, try it and see how it turns out?
And then tell us? ;)
Alvin in AZ
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charles wrote:

Nope, cool in still air means cool in still air. Cool in ash takes longer as the ash acts as a refractory. Yeah, the draw is after the quench and the cleanup with a wire brush. You'd be surprized at just how accurate a 'kitchen oven' is these days. I use a computer controled oven myself, but you can get good repeatable results in the kitchen. Preheat the oven, put in the part, after two hours take it out and set it on a rack to cool. At 375, it should have a golden brown oxide color.
Charly
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as
'kitchen
get
should
Ok, now heres a question. I did a couple of large blades (5160 new material) in my oven a while back at between 350 and 400F for 1 hour soaks, two times. I used a K type meter to watch the temp in the gas oven and it swings back and forth 20 to 40 degrees either way and I set for the middle. I got that golden brown color each time. Really liked it and have been thinking on doing a blade and leaving the color... Anyway I just did another blade from the exact same material and used the same treatment to temper it. Used a thermocouple to monitor the temp. Virtually the same process on exactly the same material and got almost no color on the metal. What gives? In retrospect I'm wondering if I might have opened the oven door more times the first time around and just leaving it alone might have cut out the available oxygen - thus much less coloration? Seems like something was different but can't put my finger on it. This last blade seem springier than the one before with - roughly - similar geometry. The new one is flat ground and the one before is convex.
GA
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I don't know. :/

Sounds like they ended up with different tempering. :/
The "oxide coating color" of course depends on surface texture and a number of other things like oil on the surface, but somehow that doesn't seem like enough to explain this big of a difference.
A few months ago I re-drew the temper on a few blades I had around here some were O1 and some were 1095 and they all got the same golden color at 425F for an hour. They were all pretty much the same shiny finish to start with tho ("polished" on the fine grit deburring wheel).
My reason for drawing the temper so far was just an experiment. Retained austenite transforms to secondary martensite or secondary bainite at 400-450F. The hardess tested out to reflect what the books say they should have been also.
When I draw at 325f or 350F my blades stay white, if they were polished first, which is hardly ever.
GA, do me a favor sometime and heat treat some 5160 but only draw the temper in boiling water for an hour and see how strong it is. :)
Alvin in AZ
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By the third temper I had it shined up pretty good so no oil and no significant oxide. I'm about convinced that I did the previous batch at around 450. I was going for toughness since the blades were both "fighting" blades. This one never went more than 420 and that was just breifly while I was adjusting the oven temp. Oh yeah, I reread my last post and overstated the swing of the oven. Thirty to fourty degree was total range not plus/minus from center. I was shooting for 375ish and got from 360 to 400 in constant transition
Kind of unrelated but I did something this time that I didn't do before that might have an effect on the steel. I pulled it from the quench as soon as the color was gone from the blade for a couple seconds, then put it back for several more seconds and swirled it around a bit and pulled it out again while it was still pretty hot to the touch. I file tested at that point and the file bit when I put some good force into it but skated if used lightly. Kind of worried me till I picked it up again after it sat and cooled for a while and it had that "hard feel" to it that I was expecting. What kind of formation can you expect if you quench it over the nose curve and then let it air cool from, say, 600 degrees?

Speaking of which, I went looking for a temper graph for 5160 but didn't find anything. You got one or a reference?

Got a geometry in mind? I got some quarter by 3/8ths sticks that I cut off the tang of this last blade to play with. Does it matter if they are just kind of square?
GA
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That sounds like the explaination to me.

Oh heck. :/ You need to move up to the high quality stuff like I use... a "Toastmaster System III Toaster Oven"! It doesn't swing nearly that much (course it won't hold no sword tho;) and the dial mark was so far off, I used MEK or something and removed the mark and drew in my own. ;) (but still go by the thermometer)
Actually, now that I think about it, I use it in the house, it won't work worth anything outside with the slightest breeze. Is that what's going on?

I want to give this one more time than I have time for right now. Snap judgment sounds like you got the same products you would have gotten anyway, they were just postponed. If you got some bainite it wasn't much and it won't hurt anything anyway? :)
With 5160 you have at least 100 seconds to get down to 450F -after- having only 4 seconds to get it under 900F (glowing) and still get martensite and no bainite. To get to 600F you have 50 seconds.
I've got a book titled "Bainite In Steels" (Institute of Materials 1992, not ASM).

You betcha! :)
I made some photo copies of 8660, 5160, 9260 and L6/4370 and several others while I had the Heat Treater's Guide "checked out" from the UofA. :)
Been meaning to mention that to you guys actually.
The only real disappointment in the heat treater's guide is the fact that it doesn't address tortional impact testing -at all- and the heat treater's trouble shooting section is really lame.
It's not "an authored book(?)" it's an edited collection of free information bound up (real pretty) for $274 (used price on amazon!).
Funny but it didn't "check out" (the librarian screwed up) and when the alarm went off, he hurryedly;) and embarassedly;) killed the theft device and got me on my way. Later looking at the slip and checking it out on the internet... the UofA still thought it was on the shelf. :)
If it had been what I thought was a really-good-book that might have been a quandry(?) for me to solve. ;)
The librarians know me now and are glad to see me, even. ;) I talked to them about what happened when I brought it back.
Funny how that used-to-wouldh've been the "expected" thing to do for "a man" but not now, huh? :/

Sounds perfect, having more than one sounds really cool too. :) Do whatever it is that you need to do to get a feel for how strong one is when simply drawn in boiling water for an hour.
Hmmm... 1/2 hour in the freezer for one of them? ;)
Strength prob'ly won't be detectable but hardness will increase in the cold treated one. Done any cold treating yet?
That extra hardness generated by the cold treatment remains through the normal tempering treatment/s with no loss in "toughness". -ASM Tool Steels [paraphrased but true]
In other words, you gain 1/2 to 1+1/2 points hrc (to even 2+1/2 hrc points with something like A2 or D2) and they remain, as-in, -added to- the hardness otherwise expected... with no loss in "toughness"!
Need proof anyone? :)
Hmmm... you know, if a blacksmith doesn't understand how soft -retained austenite- is ...who the heck does? ;)
Alvin in AZ
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Yeah, I got one of those toaster ovens. They work pretty well. The last shortsword I did just fit in the gas oven lying flat from corner to courner and I said to myself "self - thats the biggest blade you can make". This time I figured if I couldn't stuff it in the oven then I would go for a quick bluing in the forge. The blade went into the oven from the far bottom corner to the top close corner after I cut an inch off the tang (made purposely long to facilitate handling while heat treating - I drill a hole in the end of the tang and bolt another piece of steel to it). So this last blade is the longest one I can make at this time....

:-) Do you know how many of your posts I skip over till later - when I have the time they require (and deserve) to respond?

Now this is the kind of thing I've been wondering about. I knew there would be some secondary critical curves to work with but haven't seen the information for it. Somewhere in "the book" that I haven't got to yet? What happens when you get below 900 and slow the cooling for more than 50 seconds? What if you get to 600 and stick the blade in a pile of ash to slow cool?

Can you send me a copy of the TT and temper graphs for 5160 and L6??? You got my email address right?

Is there info in there that would not be in the ASM book? At that price I'd be looking for an "all in one" manual - and that's just a wish list at this stage ;-)

It's a strange thing... I know human nature doesn't change much but in this respect things definately have changed. When I was about four or five a soda machine dumped a bunch of change and I was told "it's not yours to take". Now days most folks would brag about the machine giving them a bunch of free cash. And it is getting worse. People are starting to act like the only restraints that count are the enforced legal restraints. If you can't be caught then it's ok... They've put up a bunch of traffic cameras at some of the intersections in town here. Run a red light and get a ticket by photo proxy. Do you know what happens in the non-monitored intersections now?

Haven't tried it yet... I'll do that when I can get to this. Supposed to go forge weld a stack at a friends house today and I still got to clean up the metal... And here I am at the keyboard ;-).
GA
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Cool, thanks. :)

Page 180 Fig.7-4 is for 1080 instead of 5160. You have 1 second to get 1080 below 900F because there is no Cr (or Mo or hi-Mn) to slow everything down like there is in 5160.
1060 on the other hand, requires even higher speed than 1080 so the 4 seconds the 1% of Cr is giving you in 5160 is more than just 4 times the time.
Page 218 Fig.7-36(b) Sounds/looks like what you did? :)
Page 183 Fig.7-5(a) doesn't-mistakenly-show an Mf [martensite finish] line which is cool for an old book, instead shows an M90[%] line. :) It really is a good book and much better than my school book. The teacher has made up for that by handing out "topic keys" that so far total almost 2" thick. (the stuff left out of the book in his opinion) Funny thing, almost all that stuff is in MT&P. :) (and then some!:)
Page 218 Fig.7-36(abc) again. The Mf line is actually well below zero (for plain carbon steel and lower for alloy steels) so hardly ever does anyone actually do (a) or (b). So what most everybody except for me, when I leave my stuff in the feezer for a couple hours (and Ed Fowler for another guy;) are really doing instead of (a) is in reality more like (c).
MT&P strikes again, see--> Page 214 section-7.7 ;)
I have newer+more expensive books that never even mention that!
Also something I confirmed here just lately is instead of 0.83% carbon being eutectoid it's been retroactively changed to 0.77%. Weird but true. :/

In theory-> Fig.7-36(d) :)
Funny, but in two weeks (after thanksgiving break) we are going to take 11 samples of 1/8" cold rolled 1095 and do 11 different heat treatments to them one including a salt pot and lower bainite formation then test them, including clamping them in a vise and hammering the crap out of them. :)
The last sample (all austenitized one way or another) we'll leave in the furnace and simply turn it off and let the whole works cool down "furnace anneal style", that's one extreme. The other extreme we'll -water quench with no tempering- another sample. And there will be 9 others in between. :)

For sure... just haven't figured out the best way to go about it yet. :)

They used large print and large graphs, the book is huge but low on info IMO.
Like the metallurgy teacher is fond of saying "all this information used-to be given away by the steel manufactures" and has several old examples with company names on the books, with an address included to get your own "free copy".

LOL! Funny how clueless those in power can be huh? Or ...are they being "dumb like a fox"? :/

Cool. Whenever the mood strikes you, will be fine. :)

BTDT(sorta) but today it's windy as anything here. :/
Alvin in AZ
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Greyangel wrote:

Well, the fire doesn't get into the box on a gas oven, neither do combustion gasses, just the heat. I've had color variance too, usually it traces back to a particular stick of stock. Batch variance, it's an imprefekt wurld. It's the tap of the diamond that matters, and that is consistant no matter the color intensity.
On the shape difference; a little convex can make a big difference in the 'feel', compound curves are inherently stiffer to a bending force. Don't get me wrong, stiff can be a Good thing. Think about the development of plate body armor. Plate started out with simple curves and thickness, and finished highly fluted and much thinner. Why? Because compound curves are harder to deform from their shape, so you need less mass to provide the same level of protection. My bet on the difference is shape, not heat treatment.
The oxide is really thin, mere molecules deep. Leave it if you want, but it does wear off quickly.
Charly
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The shape difference makes sense on the springyness. As for the color... Same batch of material. It starts life as a 22 foot bar and they cut it in three to ship. I'm for Alvins theory on the finish of the blade at the time of temper at this point. Possibly I tempered at a higher temp the last blades too. I'd been experimenting with small stuff for strength and knew exactly what I was doing at the time. Now the details are kind of hazy... ;-) I like the diamond idea though. I'm thinking on finding a machine shop that can do hardness testing for me. Any idea how common it is for a small time local machine shop to have that equipment and what range of cost they are likely to ask?
GA
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