How do I anneal 1095 HR?

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Milt

Milt

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I bought some 1/4" 1095 to make a clamp. Not knowing much about metal, I ordered HR instead of CRA. I was able to drill holes, but it was difficult, and oddly I was unable to drill one of holes all the way through (1/4" holes).

So I heated it up until it lost it's magnetism, and let it cool overnight. This morning it was soft enough to tap threads, but not easily. I am wondering if the cooling down process was to rapid. (I simply shut the gas off and walked away). Did I get it too hot?


Could someone tell me the proper way to anneal HR 1095- in Newbie terms!


Milt
 
Your forge may not hold enough heat and it cooled too fast. You can buy perlite from wal-mart, lowe's etc in the garden section, it looks like little foam balls. Put that in a bucket and stick the steel you want to anneal into it. Would be nice to put some more on top and adding a red-hot piece of mild steel to the perlite first would help it hold heat longer. Last time I bought it, it was around $5 for a bag.
 
the last time I did it,We always have a fire in the winter we had built a fire and the it was almost gone just some coals. I spread the coals out (I did a big piece) put a layer of coals on top and waited till it got dull red (It took some time) more coals and covered with a good bit of ash. Next day when I got home from school reached a grab it drop it cussed and got some tongs it was still around 400 and I still had a few coals. I cut like butter. I have also stuck it in the forge brought it up just below temp and shut the forge off pulled the burner out and plugged it and the door with kaowool and left it over night.
 
Well one thing that would help are you using a forge for the heat treating process? Or you using a Oven to do your heat treat in? If you are using a oven then put the pick in the oven and set the temperature for 1500 degrees and hold their for two hours. :)

Do this before you go to bed, in the morning when you wake up the oven will be cooled down and the job will be done. Do not open the door til all the heat has gone. That is why I said, at bed time. Do that and check the hardness of the steel. If you do not have a hardness tester then use the file test, its better then no test at all. Hope this will answer your question. :D

But there are some out there that will do it different. Try this method and see if it works for you. And by the way welcome to the bladeforum :yawn:
 
I use a gas fired oven. It is a piece of pipeline pipe- 12" in dia. and 16" long. It is open on both ends. I think I should make doors for each end so that I can close it during the cool down phase. I do not yet have a thermometer in it, but this will happen soon. I cannot use any type of timer with this unit- at least at this point.

Once the pieces got hot enough to be non-magnetic, I only left it in the oven for about 5 minutes. Perhaps that was not long enough.


Milt
 
If I am not mistaken, to anneal steel, it probably takes several hours dropping the steel's temperature say 50 degrees per hour to around 1200 or so from say 1500 or 1600 then freely in cool air. If your gas fired oven is opened on both sides, i highly DOUBT you annealed it much if at all.

What I am saying is probably from full hard, but you probably want to heat it up and then bury it so it cools very very slowly or heat it up in a kiln like Terry said to some temperature (1500ish) and then turn off the oven and let it cool down over night.
 
Milt, the ideas of overnight cooling all work fine with 1084, 1080 and other steels with less carbon, but will give you no end of troubles with a hypereutectoid steel like 1095, and is exactly why you found it less than pleasant trying to drill your holes. Heating to above critical (or even non-magnetic) and allowing the steel to slow cool is called a lamellar anneal and it forms coarse pearlite within the metal. This state is made up of extremely hard carbide segregated out into sheets between areas of soft iron, so such a blade will bend and seem soft but will rip drill bits up! No amount of reheating (tempering type) short of a full normalization will have any effect on these sheets. But of even more concern is that leaving hypereutectoid steel that is in solution to slow cool will allow all the carbon in excess of .8% to fill the grain boundaries and cause a very weak an brittle condition that would be rather bad for a knife.

Hypereutectoid steels, and forgive me for not explaining the term which simply means steel that has more carbon than the eutectoid or .8%, really should be spheroidized if you are going to be doing any machining with them. It is best done with well controlled heat treating equipment but it can be approximated in a simpler shop as well. To accomplish this with just a forge you should heat the steel up and normalize it well to homogenize things and get any carbide our of the grain boundaries that may be there. Next reheat it a couple of times at lower temperatures to refine the grain and on the last cycle heat it to just above non-magnet and then quench it in any oil you may have.

Now for the anneal- reheat the hardened blade to red but never allowing it to lose magnetism, do this several times and it will ball all that extra carbon that you trapped in the quench up into little spheres suspended in a soft iron matrix. The steel will be soft and bendable and when a drill or mill hits those little spheres they will just move out of the way and allow you to keep cutting
.
 
Kevin R. Cashen said:
Milt, the ideas of overnight cooling all work fine with 1084, 1080 and other steels with less carbon, but will give you no end of troubles with a hypereutectoid steel like 1095, and is exactly why you found it less than pleasant trying to drill your holes. Heating to above critical (or even non-magnetic) and allowing the steel to slow cool is called a lamellar anneal and it forms coarse pearlite within the metal. This state is made up of extremely hard carbide segregated out into sheets between areas of soft iron, so such a blade will bend and seem soft but will rip drill bits up! No amount of reheating (tempering type) short of a full normalization will have any effect on these sheets. But of even more concern is that leaving hypereutectoid steel that is in solution to slow cool will allow all the carbon in excess of .8% to fill the grain boundaries and cause a very weak an brittle condition that would be rather bad for a knife.

Hypereutectoid steels, and forgive me for not explaining the term which simply means steel that has more carbon than the eutectoid or .8%, really should be spheroidized if you are going to be doing any machining with them. It is best done with well controlled heat treating equipment but it can be approximated in a simpler shop as well. To accomplish this with just a forge you should heat the steel up and normalize it well to homogenize things and get any carbide our of the grain boundaries that may be there. Next reheat it a couple of times at lower temperatures to refine the grain and on the last cycle heat it to just above non-magnet and then quench it in any oil you may have.

Now for the anneal- reheat the hardened blade to red but never allowing it to lose magnetism, do this several times and it will ball all that extra carbon that you trapped in the quench up into little spheres suspended in a soft iron matrix. The steel will be soft and bendable and when a drill or mill hits those little spheres they will just move out of the way and allow you to keep cutting
.
Click to expand...

What temperature range are you talking about, when you say red. How close to A1 is the ideal temperature to do this. Or is it a pretty broad range? Is this the same structure you get with spheroidizing?

I have a set up that allows me to spheroidize steel, but I would like to try this technique just for the sake of experiment.

Thanks Kevin. Hope your trip went well, Fred
 
If you have a kiln or oven that is controllable and capable of ramping then a proper industrial spheroidizing is best for steel that must be machined, i.e. soak at 1375F for at 30 minutes and then cool no faster than 50F/hour to below 950F, this this method your mills and drill are guaranteed to still respect you in the morning.

The other method I described is a way to fudge it in the absence of the ability to hold exact temps and ramp. The idea is that you cycle just around ac1 (just above and just below) a few times to allow the carbides to gather together instead of going into solution.
 
I see a lot of respected blade smiths anneal in ashes, and I usually see them using a fairly large container of ashes (like 10 gallons or so). Not everyone has a kiln or an enclosed oven, but most people can rustle up a big bucket of ashes. I know traditional Japanese smiths use rice straw ash, but not sure if there's a big difference in which ash you use... I would assume that only the insulative properties of the ash matters but I don't know for sure...
 
Why do you keep opening very old threads? If you have a question you are much better just starting a new thread!
 
Ian,
Please fill out all the info in your profile ( age, location, hobbies, occupation, etc.) and also look at the date of old threads you pull up in a search.
Do not resurrect threads older than a year. If in doubt, post a new thread and link the old one as the subject you are asking about.





If you don't have an oven that will do metallurgical annealing, use the forge.

1) Heat to above non-magnetic (1400-1600F) and hold it there for a few minutes. Cool to black ( below 900F) and quench in water.
2) Heat to just below non-magnetic (about 1200-1300F) and hold there for a few minutes. Cool to black and quench in water.
3) Repeat #2 a few times.

Few smiths I know slow cooling in ashes - it is actually more likely to give a harder to drill and file structure. The slow cooling in an oven with 50F/hr steps will make spheroidite, which is the softest structure to drill and file. Slow cooling in ashes will form fine pearlite that is tougher to drill and file. Quick cooling once below 900F will cerate coarse pearlite , which is easier to drill than fine pearlite.


Old thread closed.
 
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