Heat Treatment - please help

A

andybill

Joined
Dec 29, 2008
Messages
53
So far, every one of my attempts to HT has failed, all blades and bits of scrap have failed the file test. I've been working with steel from leaf springs, mower blades, concrete punches, old chisels and files.

Okay, I've read the sticky on the principles of quenching, and everything else I've been able to find on here about how this is done, and I think I've followed it pretty accurately. My process is as follows:
After forging and stock removal, I anneal the blade in ashes. It takes a few hours to get cool. I clean up the blade and heat it to the point that it becomes non magnetic, then just a bit more, then quench tip down in warm oil. I take it out of the oil when it's cooled enough to handle, clean it off, and clamp in a vise. Every time i try the file, it bites. As far as I can tell, no change has taken place. I've been doing this for days, trying to eliminate possible sources of error, and I'm out of ideas.

I'm quenching in about 4.5 gallons of used motor oil in a metal trash can, warmed with a piece of heated steel prior to quenching. I've tried swirling the blade around, plunging it in fast, putting it in slower, everything I can think of. I know there have been lots of threads about this, but I can't seem to figure it out. Any ideas? I live in Boulder, CO if there's anyone nearby. Thanks -Andy
 
That's not surprising given that you are working with a variety of mystery steels of unknown composition. Some may be medium and even low carbon steels that have been carburized. While the heat treating method you describe may work for the most basic of high carbon steels like 1084/1080 and will even likely get you some hardness in O1, what you have to understand is that each and every steel type has its own set of heat treating guidelines that have been developed by the manufacturer of the steel.

It sounds as if you have been spending a lot of time and effort in trying to piece together a heat treatment for a number of different steel types, some of them probably not even high carbon suitable for knife blades. If you desire to continue to work with mystery steel, get a stockpile of ONE steel (and a steel very likely to be a good candidate for a knife), and vary the parameters of your heat treating until you get the results you desire.

However, for all the time and effort you have put forth into figuring out what may or may not work with a given mystery steel, you could have had multiple knives heat treated correctly using a known steel. The best advice I could give you is to choose an easily heat treated known steel (like 1080 or 1084), buy what you can afford of it, and learn to heat treat it spot on. Once you've got that steel down, you can move onto a different steel, keeping in mind that it will heat treat differently than the first.

Mystery steel can be worth it, if you have a ton of the exact same steel laying around, and if you are able to determine roughly its content (you can have it tested at Fastenal and that will give you information to determine heat treatment). However, I'd highly recommend abandoning the idea of using one heat treatment and trying to match a steel to it. Pick your known steel, order a stock of it, and learn it as best you can. Remember, each time you try a new mystery steel, you are having to reinvent the wheel as far as the heat treating goes, because it will almost certainly not be the same as the previous mystery steel. One KNOWN steel = one PROVEN heat treatment.

--nathan
 
Okay, that makes a lot of sense, thanks.
I'll try and stick with the files, I've got a bunch of those lying around. Anybody have any advice for heat treating these with the setup I have?
Maybe I'll try a different quenchant.
Thanks for your help. -Andy
 
i'm a newbie and don't know much about anything but 1/8 inch thick by 1.5 inches wide 1080 is only like 35 cents an inch it's gotta be more cost effective than spending hours making a blade that you can't harden.
 
kungfucowboy said:
i'm a newbie and don't know much about anything but 1/8 inch thick by 1.5 inches wide 1080 is only like 35 cents an inch it's gotta be more cost effective than spending hours making a blade that you can't harden.
Click to expand...

Maybe a newbie - but oh so wise!.

You are right. Recycled steel is commendable and intriguing - but it is not recommended for the newbie. It is an advanced task. How many blades did you make trying to save $10? (or less)

Having said that, it is common for a file to bite into the surface. File or grind it down a bit to get through the scale and decarb. There might be a nice blade just below the surface.

Rob!
 
Rob, Nathan, and Cowboy are telling you the right stuff.

The problems in the file test may be due to the steel being no good, the HT being wrong, or the blade having decarb due to too many heats, including your forging temps and number of forging heats. Without a lot of details, it would be impossible to say which is the problem.

Admiral steel sells 1080 for $7 per 5 foot bar. Aldo Bruno sells 1084 FG, made for forging blades. Kelly has 1080.

As to the mystery steel:
The leaf springs may be worked like 5160. They may not be that, but the HT for 5160 is a start.
The mower blades most likely won't work at all.
The concrete punch ( star drill?) could be many things, some usable some not.
The chisels and files may be good steel, or totally useless. Some are mid to high carbon steel, and some are case hardened low carbon steel.

If you are going to continue to try and learn on mystery steel, only use the leaf springs. It may not be the best steel, but at least you will have eliminated a lot of possible bad variables.

The basic HT for 5160 is:

Forge at 1600F to 2100F. Stress relieve or anneal at the end of a days forging, as 5160 has high hardenability. Do not cool in the slack bucket while forging. Working the steel too cold or cooling too fast may cause cracks ( some you see and some you don't).

Anneal ( for grinding ,after forging)- heat to 1525F and maintain that temperature for five to ten minutes, hold out in air until it becomes magnetic again ( about 1250F), cool as slowly as possible in vermiculite, ashes, or oven cool.

Stress relieve ( prior to quench, or at the end of each day's forging) - Heat to just below non-magnetic ( about 1200-1250F) and hold for five or ten minutes, cool to black heat ( below 900F), repeat two or three times. Cool to room temp in air.

Harden - Heat to 1525F and hold for three to five minutes. Quench in 130F oil. Cool to room temperature.

Temper - 450F for two hours,cool to room temperature, repeat.

Stacy
 
KnifeMaker.ca said:
Maybe a newbie - but oh so wise!.

You are right. Recycled steel is commendable and intriguing - but it is not recommended for the newbie. It is an advanced task. How many blades did you make trying to save $10? (or less)

Having said that, it is common for a file to bite into the surface. File or grind it down a bit to get through the scale and decarb. There might be a nice blade just below the surface.

Rob!
Click to expand...


This is exactly what I was going to say but now I wont have to do all the typing. Thanks Rob.
 
Thanks for the replies guys, good news. While trying to straighten a warped section of one of my "unhardened" blades, I broke one in half. At first I was bummed, but then realized that this was a good sign (I think). It broke clean in half and showed a very fine grain structure. This was a blade made from a pry-bar, which I figured would work 'cause the original piece skated a file.

Anyways, what do you think? Is this evidence of sufficient hardness?
-Andy
 
andybill said:
Thanks for the replies guys, good news. While trying to straighten a warped section of one of my "unhardened" blades, I broke one in half. At first I was bummed, but then realized that this was a good sign (I think). It broke clean in half and showed a very fine grain structure. This was a blade made from a pry-bar, which I figured would work 'cause the original piece skated a file.

Anyways, what do you think? Is this evidence of sufficient hardness?
-Andy
Click to expand...
Yes that is high carbon if it broke after quenching.

The best way to test mystery metal to see if it is high carbon steel is to heat a section of it to non-magnetic and quench it in water. Next simply put it in a vice and see if you can break it in half. If it breaks it is high carbon and most likely will make a decent blade but if it bends it is just mild steel and not suitable for a knife.
 
With all deference to Bruce, quenching a piece of 1030 mild steel in water and bending it in a vise will most likely result in a clean break just as well as a piece of 1080 would. Spark testing the steel might get you a better idea, but that requires the ability to know what you are seeing and decipher it.

The fine grained break on your blade was a good sign, but not a definitive answer.

Take the broken blade and grind/file into it. Does it get hard after a little of the surface and edge is cut away? If so, then the problem is decarb, and there is a hard blade below the soft "rind" formed in the HT. Give it a try and let us know what happens.
Stacy
 
just buy some 1084 from aldo and forget messing with mystery metal....it will be worth it...trust me!!!!!!
 
I work in a salvage yard and one of my biggest inspirations in knifemaking is to use recycled steel. If it takes longer, so be it. Hopefully I'll have some hair left by the time I get this stuff figured out.

I'll mess with it some more this afternoon. Thanks boys!
 
oldold442 said:
just buy some 1084 from aldo and forget messing with mystery metal....it will be worth it...trust me!!!!!!
Click to expand...

Exactly. It just isnt worth all the trouble unless you get the steel analyized. In my business I wouldnt even try to sell somebody a blade with unknown steel. Sooner or later it will come back to bite me.
 
Wade through this.
http://www.bladeforums.com/forums/showthread.php?t=610721

If you work at a scrap yard, there are doubtlessly hundreds of pieces of metal per day that you look at and think, "I can make a knife out of that." It's certainly appealing, but like the others said, it's not as economical of money or time to do it that way. That said, if you're making knives for fun, to "waste time," and not necessarily to make money, then dive right in the scrap heap as long as you're willing to accept the limitations of the mystery metal approach.
 
jkf96a said:
Wade through this.
http://www.bladeforums.com/forums/showthread.php?t=610721...
Click to expand...

I believe one of things to come out of that thread , and some others, was the strong encouragement of those championing scrap steel to roll up their sleeves and offer some advice on working the stuff to the people who listen to their initial recommendations and then meet with extraordinary frustration.

No offense to the folks offering advice based on known materials in this thread, but you gentlemen are enablers. Not to andybill who entirely deserves answers to his questions, answers that should be coming from the folks who would encourage using unknown steels with any available quasi-liquid to quench in.

I was really hoping to see some of the folks who can only be motivated to spew venom and vitriol in “scrap vs. known steel” or “quenchant vs. improvised mediums” , to step up with some positive and constructive contributions for somebody following their approach. If you are going to get spat at for applying the logic that knowing your materials may help with success, then would it not be logical to step back and allow your detractors to back up their position with more than angry potshots at your position?

I have said before that I don’t give a hoot what anybody uses to make their own knives, but this honestly makes me angry when a guy trying to get started meets with repeated failure following a path that so many steer him down and then vanish when it is time to walk that path, only to quickly reappear to attack anybody who may suggest a clearer way.
 
I started with scrap. I read this board ravenously. I bought some known bar stock.

That said, here are some things I've gleaned from the process regarding the use of scrap steel. I have learned these things 70% from reading, 30% from doing, so take them for what they're worth.

One, learn to judge sparks. I'm not well versed enough to tell you more. Google it.

Two, learn to try some pieces with various heat treat procedures. For example, heat to nonmagnetic and quench in your motor oil. If it doesn't "break like glass" when you whack it, and/or doesn't pass the file test, then do the same thing again but with a faster oil like mineral oil. If it still doesn't pass, try brine. If it won't pass any of those, you can try increasing the soak time. It is 100% trial and error until you figure out a heat treat procedure that will give you what you want. Without the ability (I don't have it) to do precise metallurgical testing via micrograph, or at least without a hardness tester, that's about as good as you can get.

Three, don't ever be satisfied with just "ok." "Pass the file test" doesn't mean everything worked out just right. Always try to improve your procedure. For me that meant moving away from motor oil to mineral oil, and away from scrap to bar stock.

Four, since it takes so much time to get a good HT figured out for a mystery steel, it's good to use that time on a steel you have a whole bunch of. If you can figure out a HT for files, or a specific batch of plowshares, or axles, or whatever, then use it. If you have to take each individual knife and go through a guessing game to get a HT, then it's not worth it, IMO.

Five, if you do in fact have a consistent load of steel, get some analyzed so you don't have to guess. Then it's not mystery steel anymore, and you can find HT info on the web.
 
In response to Kevin's post,
Andybill said he had tried everything and nothing worked. He said he could not figure out the information on HT and scrap steels. His profile says he tends to get over-involved with projects. He said he thought that since a piece of metal skated a file it would make a good knife ( glass will skate a file, but makes poor hunting knives). ....He needed help in learning.
If he continues his quest with so many variables and no base of knowledge to start from, he may give up and abandon his new hobby.
Getting a starter batch of known steel,following a tried and true HT regime, and making a couple of successful knives will give him far more ability and the confidence to take on that mystery steel later. Once he knows what he is trying to achieve, he will have a far better chance of getting those results with unknown steel.

I have always said that you should learn on known steel, and then experiment with unknown steel after you have mastered the procedure.

Two scenarios:
1) You go to a surgeon for a shoulder operation. He says he hasn't done that surgery before , but he went to a good med school, interned at a good hospital, and did a three year residency before he started doing things on his own. He feels he can do your shoulder some good.

2) You go to a surgeon for a shoulder operation. He says he read a bunch of online medical sites,they were confusing to him, so he experimented on a lot of people who couldn't afford a doctor, killed his first 20 or 30 patients and crippled a couple dozen more, but now he seems to be getting the hang of it and is ready to try out some new procedures, like your shoulder surgery.

WHICH ONE DO YOU WANT TO GO TO !

Stacy
 
Well I chewed on it for a while and I'm convinced. Known steel seems like the way to go.
The 50$ knife shop made it seem so simple. High carbon steel = good for knives. Quench in oil and bingo! ...obviously not so easy.
I read through that other thread, solid advice there.
I'll try 1080 or 1095. Besides, handles and everything else can still be made from recycled materials. Thanks guys
-Andy
 
I make knives as a hobby. I make them mostly from new, known steel and worn out Nicholson and Simonds files. I've never sold a knife and don't intend to. I give them away and tell the recipient that if it fails they haven't lost anything. Most say they won't use them because they don't want to mess them up. I tell them it's made to use but most say no, "I'm just going to keep it to look at". The only test data I get is what I do with a knife on my own.

I also like to play with scrap steel. lawn mower blades, cultivator sweeps, knifing slide blades, and a few other sources. I don't put the labor into making a knife before I have tested the scrap. Spark test first, then clean up a piece to where it is shiny and do the heat treat thing. If the first time doesn't work and the spark test indicated it should, I'll try something different, changing one procedure at a time. If I find a process that works in a few tries then I will make a knife. If not, it goes in the scrap pile.
 
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