annealing?!?

D

dbreeze225

Joined
Sep 12, 2014
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hey guys if the answer to my question is already posted some where i am sorry. I am in a little bit of a info overload from all the stuff i have read. i have been having trouble with type of steel i do plan to order some knife steel soon. But right now i am using a file i found it is a old nicholson says made in usa so from what i am told its possible to do it with that. Also it is one of those "4 in 1 files" so part of it has very rough teeth. last night i annealed it (or thought so). following what i have read i heated it till it was evenly red hot and NON magnetic and let it sit there for a few mins then put the fire out and let it cool slowly in the fire (just coal and ambers) all night. This morning took it out and it was still a lil hot but after a few hours sitting out side it was ok. So i am in the process of grinding all the teeth off the file and it still seems very hard. My main question is, is there any way to tell if it has been fully annealed? with out doing it all over is there any way i can check this at the point i am at now? If it isn't fully annealed i can throw it in the fire again right? Lastly i was thinking (this usually leads to trouble) when i had it red hot when annealing should i have thrown this file on a anvil and beat it with a hammer. i figure this would flatten the teeth so there wouldn't be as much to grind off. It makes sense but my sense doesnt always translate to reality well. THANKS guys appreciate any answers and again sorry if this info on how to check if its annealed is already up some where i just have read so much i cant remember everything so sorry
 
What you did should have made pearlite. However, very slow cooling can make fine pearlite, which is much harder to grind and file than coarse pearlite.

Take a good file and file on it. If the metal files away, it has been annealed suitably. If the new file just slides around, the file isn't soft enough yet.

Repeat the non-magnetic heat up and take out of the coals. Let cool until it is black and no glow is seen. Quench in water. Check with the file again, it should file OK now. You can do the heat/cool/quench a couple times in a row if you want to, but one cycle should be enough.
 
really??? i thought quench was only for hardening/tempering and a long slow cool like i did was for softening aka annealing. if that is the case whats the differnce between the 2 if you do the same thing wont you get the same results how does one way harden and same thing soften? sorry i have been doing ALOT of reading on these subjects recently maybe i got it backwards.
 
If you quench from austenite...at 1450-1500F, the steel will convert to martensite when it cools enough, which is the hard steel structure knife blades need to be. This is a hardening quench.

If you quench from 900F ( black heat) the steel will be coarse pearlite, which is soft. Thios is a quench to stop the cooling and keep the steel soft.

If you slow cool from austenite, the steel will become coarse pearlite at 900F, and then morph into fine pearlite as it slowly cools to room temperature. Fine pearlite is much harder to file and drill than coarse pearlite. It will even skate a file.

With a HT oven, you can heat to 1200F and hold for a while ( 15-120 minutes), cool to 900F, and then quench to form spheroidite, which is the softest and most machinable structure of all.

A lot of this is in the stickys under metallurgy.

The old "long slow cool" was a left-over from blacksmith days, when they were mainly working with iron and low carbon steel. They would heat up the bar and stick it in ashes or vermiculite overnight. You still see this given as a good method all the time but, metallurgically, a fast cooling from 900F is far better.

Sticking a bar of high carbon steel in a fir pit or wood stove and leaving it there overnight is often seen on YouTube and mentioned online, but I can tell you that it is a good way to ruin your bar of steel. Decarb and burning can be pretty deep in a bar treated that way. The final blade may not turn out nearly as well as if it was properly annealed.

To anneal carbon steel right, use any method you have available (forge, propane torch, welding torch, charcoal grill, fire pit) and heat the blade to non-magnetic. After a minute , remove and watch it cool. It will go from a bright red to a dull red to a barely visible red, and then rather suddenly turn black. Give it about another 15 seconds, and dunk straight in a bucket of water. That's it!
 
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ok THANKS ALOT great info! i really appreciate it... i was using a round carcoal grill with a few well placed small holes just big enough for me to stick the nozel from my air compressor to get the fire real hot. is this meathod of watching the color pritty accurate? i think i am going to buy one of those temp. gauge infrared guns if i can find one cheap enough and i think i am going to try and find it local but if not i guess ill order. if you were buying one of those what temp. range would you get .....for example home depot has one but only goes to 600 degrees so cant use that but how high do i need it ? again thanks very helpfull
 
I don't recommend buying one at all. They are pretty useless for working with steel in the 1000-1600F range. They may say that they are good for that heat, but there arfe things that makes them useless.

Judging temperature by eyeball in a shady place is probably more accurate.

Additionally, a charcoal grill with an air blast isn't a particularly good method of heating steel for knives.
 
Wow really eyeball is better than using a temp. gauge? I was looking on line some are fairly cheep and some are very expensive. I have seen $10 all the way to $2,000. I wont even bother then cause i cant afford a expensive one.

Is there a reason that the charcoal grill plus air isnt that good? I was more than able to get the steel red hot. What about this... i was in home depot the other day and got a bunch of blocks a bit thinner than a cinder block (with no hole). Also got stones that are probilly 1 and half foot to 2 feet by 3 to 4 feet and a couple inches thick. I was planning on placing these block so they form a small fire burning area similar shape to a forge. And using one or two of the big flat ones to cover the top. Plan on leaving a small hole in the front to put the steel in and out and also to blow air. Oh yeh one block has a hole in it i was planing on putting that on the back so i can blow air in there. I have a area of sand covered ground in my back yard (from where a pool used to sit ) i was going to do this there can i just burn the fire on the sand or do i need to lift it up? Long story short i was going to do this but then used the charcoal grill and air thinking it would produce the same results and be easier. But would the block work better?.....is there anywhere i can find either video or instruction of how to make a "forge" ( for lack of better word) with the blocks?

Stacy E.---- THANKS i appreciate all the input. you have been VERY helpfull.
 
The metal in a charcoal grill is pretty thin and charcoal burns away pretty quickly in forced air. A coffee can propane forge is a cheap alternative to purchasing a forge and the heat can be regulated somewhat.
Unless the bricks you are looking at are refractory bricks, they are likely to crack and crumble when heated.
 
I am guessing you haven't read the stickies. They cover a lot of what you have asked about. A simple "two-brick forge" can be made from two soft firebricks, some bailing wire, and a propane torch. Using the BF search engine (also in the stickies), will find you hundreds of threads on building everything from a one brick forge to a big welding forge.

A really good small forge is made by one of our forum members. The forge is called the Atlas Mini-Forge. It comes in a couple sizes now. All you need is a propane tank and you are up and running. He is constantly improving and updating it,

http://www.bladeforums.com/forums/showthread.php/1153039-Atlas-Mini-Forge-w-30k-BTU-Burner
 
THANKS guys.... i have read some of the stickies and alot of other stuff on the web. sorry if some questions are already answered. i have read so much recently i have a lil sensory overload i just cant remembe everything yet its too much info but thanks really you have been very helpfull
 
Sorry to butt in here, but I don't wanna start a new thread for a quick question that does relate to this thread.

Stacy, I've been doing the "redneck" sub-critical anneal that I happened to learn about from you quite a while a ago on here, by heating to critical, cooling to a black heat, then water quench and I'll repeat 3-5 times.

The only thing I've still been a little unsure of is, what exactly is a proper "black heat". I do it at night and wait till the blade has lost all of it's color while being held in basically a pitch black area, so would that be a proper "black heat"? I've seen some guys call a blade that's lost it's color in a lit up shop a "black heat", so I just wanna make sure I'm not letting it cool too far below ~900*F before I quench.

Also, can you "overdo" this, like for example if I were to repeat this step 10 times, could that be harmful, or possibly even beneficial? I do know that a blade can be over normalized where the "grain" becomes too fine, even though that is a bit different that the sub critical anneal. Anyway I'm just curious ;)

Thanks :)

~Paul
My YT Channel Lsubslimed
 
Hey guys and stacy....I have one more question for this thread. And i am sure this question is answered in the stickies some where but i would really appreciate a answer. Honestly i dont have the time right now to read everything (i know that sounds bad) but...i am so tired need to sleep and i have to wake up early (got to get a tooth pulled FUN!!!) But i want to take a trip to a couple stores on the way home and i wanna make sure i get the right stuff. So again sorry for asking but...i have been cruizin through the stickies and post's and have decided making a small propane forge from fire brick is probilly alot better than using charcoal. So finally found a place that sells fire brick near me (hence one of the stops in the morning) That part i got but i was reading some where that not all handheld propane nozles will work. But it didn't say exactly what kind i need. I already have a hand held torch it is just a standard nozel with a trigger button to light that sits on a 14oz. tank is this suitable?? It would be nice if it is cause i don't have alot of money to spend right now. If not what kind do i need? The only problem is where to get it i only have two small hardware stores and a home depot (wallmart too idk if they would have anything). Is the one i have good? if not can i find a good one in home depot? What kind? Also if i cant find a nozle (if the one i have wont work) what if i set up 2 torches blowing into brick at the same time would that work? Last thing promiss....how many bottles of propane ( the 14oz. bottle) would i need for the whole process (anneal, harden , temper). Ok thats it if anyone can help me out a lil bit by morning i would REALLY APPRECIATE IT! Now that being said time for bed i got a fun day tomorrow YAY getting tooth pulled GREAT DAY! THANKS AGAIN guys i know some one will help
 
This is a quick video of the first forge I built (over 5 years ago). I used a paint can, some ceramic wool ("kaowool") to line it and then put some refractory cement (satinite is a good one) on top of that.

[video=youtube;9yqIVpezBKs]https://www.youtube.com/watch?v=9yqIVpezBKs[/video]

Anyway, I got the torch you see in the vid from lowes (I'm sure home depot has it too) and it worked fine for getting the forge hot. I did use MAPP gas though as it burns quite a bit hotter than propane. You torch might work alright, two would be better, but it really all depends on how well your forge can absorb and even more so reflect heat off of the wall, which it what enables the forge to get hot enough and maintain that heat more evenly and efficiently

There are two different types of fire bricks, hard and soft. The hard ones (kinda of a light gold/tan color) you can buy from places like home depot and can work well for using as walls for making a smaller area to contain the charcoal or coal in those types of forges. ***These are NOT what you want when making a propane forge!!

The soft ones (white in color) are sold at specialty places. Those are the type that guys make single or two brick forges from, because they absorb and contain the heat very nicely. They can be ordered online (but shipping sucks) . But first check online or in your local phone book for a place near you that sells pottery making supplies/equipment. They have pretty much everything you need to make a good forge, including soft fire brick, ceramic wool, refractory cement for lining etc. since those are used in pottery kilns to fire and glaze, well, pottery.

That's pretty much as much info I can think of right now, you'll have to use the bladeforums search (the link is in the sticky up top) and read the stickies to get a better idea of what you really want etc.

Also the torch I used, was a BernzOmatic TS.... I forget the number.. But it produces a nice hot swirl flame and works just as good whether it's right side up of upside down, as opposed to those cheap plumbers type torches. They probably have a newer model now than the one I bought years ago but it's probably the same. ..... (I just searched and the BernzOmatic TS8000 looks exactly like the one I bought with the same, or better specifications..)

All in all, I would just slow down if I were you and do a little more research so you can save your money and do things the right way the first time around. Buy once, cry once! But that's not to say that you can't get away using some type of crudely set up forge, but you WILL end up upgrading if you choose to take that route.

Hope that helps some man, and good luck at the dentist! :)

Now, answer my question Stacy! :D lol jkjk

~Paul
My YT Channel Lsubslimed
 
THANKS...... one quick question before i go to have another tooth ripped out of my mouth.............i did a search for pottery stores as you suggested and they are very few and far between near me....i was thinking about doing something like in your video. iam sure i can find some metal cylinder to use...from what i have read your supposed to put ceramic wool or similar on the in side and then cover it in refractory cement..i cant find the wool is there anything else that i could use in its place (something that i might find at home depot or hardware store) do i absolutly need the wool what if i just put the cement right on the metal cylinder what would happen would it work . i know it wouldn't be the best but could i get away with it for now? thanks again
 
also dont know if it matters but since i have propane torches and a few people now have said mapp is hotter so i think i will add 2 torches to make up the difference
 
Yes, black heat is when it stops glowing and looses all radiance. The steel is around 900F at that point. In the dark, you will see nothing. In normal light, the steel will take on a very non-reflective black look as it reaches this point. If you let it cool in air a little lower, then dunk it in water to end the cooling time, no problem. It is the very slow cooling to below 200F over hours that causes fine pearlite.

For a sub-critical simplified anneal, my general description over the internet is:
Heat to just below non-magnetic and hold it there for a minute if you can,
Cool to black,
Count to 15,
Quench in water,
Repeat a time or two .....,
Drill and grind.
 
The thing to remember about file steel is it's going to have more carbon than even 1095, and will therefore have more carbides (iron carbide=cementite) than most any plain carbon steel you'll deal with. The carbide is what makes it hard to grind even when annealed. Judging by the posts, could it be possible you just underestimated the effort needed to grind steel in general? The pros here make it sound easy, but it does still take some effort.

I think Stacey may have accidentally gotten his times and types of pearlite mixed up. Holding at high heat, but below 1375 F, gives you coarse pearlite, which is softer and easier to grind than fine pearlite. Holding at lower heats gives finer pearlite, which gets progressively stronger as it gets finer. Air cooling will give fine pearlite, while letting a blade cool in the oven overnight gets coarse pearlite.

The trick is with these file type steels, and when cooled very slowly, they will have carbide surround each grain, as well as be present within the pearlite. Pearlite is a mixture of carbide and ferrite where the 2 are arranged in alternating layers. In coarse pearlite, the layers each are thicker, while fine pearlite has thinner layers of each. The strength of pearlite is inversely related to the thickness of the layers, in other words, the finer the layers, the stronger the pearlite. By the time the blade has cooled to black in air - 900 F or so - the pearlite reaction is mostly if not completely done in plain carbon (1095, 10xx) steels. Quenching from there just lets you get on with whatever you need to do. Once formed, pearlite is very stable, and takes long times at high temperatures, but just below 1350 F, to do anything to it. If held at say 1300 F for a long time, like hours, the carbide layers will move around and form little balls or spheres.
 
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