1095 non magnetic at what temp

SteelSlaver

SteelSlaver

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Feb 17, 2007
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I want to check my home made oven at higher temps and it struck me that if I keep kicking the temp up 10 from say 1400 and checking a piece of the 1095 I got from Aldo with a magnet when it went non magnetic I would have a solid point to compare my ovens readings to. Now, I know I need to have 1095 at 1475-1525 to harden it according to several sheets I have saved but, exactly what temperature does it go non magnetic. I could use the non magnetic temp for 5160 also, or is it always the same at what 1420f?

Thank you Much Jim

PS I did a search
 
The same.
With little deviation, ferrous metals loose magnetism at or about 1413 degrees. It's the iron in the steel that is magnetic.
The austenizing temps are a little different.
Use the magnetism as an "indicator" that you are approaching your quenching temps for the given steel.
You will notice your steel go non-magnetic BEFORE you will observe the decalescence --(that shadow in the steel disappearing!) You will want to quench after you observe that decalescence, which is higher than non-magnetic.
 
As Karl pointed out the Currie point of iron is around 1414F., often designated Ac2, being above Ac1 where transformation begins, but below AcCm (Ac3 for lower carbon steel) which you do not want to exceed. The other temperatures are given the letter labels because they vary due to alloying and heating rates while the Currie point is a little more stable.
 
Remember one inch per hour:
1500 degrees at this point, it will be non-magnetic but actually it starts the process at around 1200 degrees. At 1500 degrees you will end up with a test at 65 Rockwell. At is point quenching in oil or what-ever you are using to do the job in. The steel is removed and placed back in the oven at 350 to 400 degrees for 2 hours. :)

Now the temper process softens back the hardness that you produced during heat treat. Now when you test the steel it should be about 59 to 61 on the Rockwell. Here in my shop I strive for 59 to 60 on the Rockwell. ;)

1095 is a great steel to work with and it makes great knives. Hope this can be of help to you. Have a great day in what-ever to do.:thumbup:
 
To pick up where Kvinn left off:
The curie point is reached at 1414F. It may be somewhat difficult to tell exactly when this happens as the effect is not a sudden here-it-is-there-it-went observation. Once the curie point is past, it is even more difficult to find it on the way back down during slow cooling. Many other calibration devices are far more accurate. Try a calibrated pyrometer, or temp-stix.
Stacy
 
I have temp sticks but nothing that high and a high quality probe that goes to 900 degrees, but I was looking for a way to make sure I am dialed in at around 1400 to 1500. Do they make a 1500 temp stick? Where can I get some? I have the temp adjusted correctly to ambient. and it reads close at 900. (reads less than 10f cold) I know the real stuff happens at around 1500 and want a way to check how accurate I am at those temps. I have even used the thermo couple and old analog meter from my forge and it shows about a 25 degree difference at 1500. Thats what has me wondering how close I am at 1500. If I want to harden 5160 at 1525, it would suck to be at 1550. The pieces I have hardened so far seem very hard and after tempering do the brass rod test well. I just want to be dialed in as close as I can get. The book Tool Steels Simplified has a method where you use to melting point of a certain brass, well actually the point at which it starts to solidify. I was hoping to find a method a bit easier. Just how close do I have to be and how accurate should my thermocouple be. I am using a long type K with a ceramic sheath and a pid from Auberins. I understand how to harden and temper. I just want to do it as well as I possibly can.
 
Most of the guys I know using thermocouples are able (or so they say but I trust them) to dial their forge to +/- 3 degrees or so. The consensus from these guys is that a larger forge is more controllable for temps because the extra interior volume helps to equalize the temps inside. I'm probably going to build a larger volume forge next time because I'm having a hard time getting temps to hold in my freon tank forge tank fire squirter.

Will
formerly known as badbamaump
 
Hi,

I unserstand what your going for but I'm not so sure it will work out so well. Boiling water boils at 100 celcius and is a first order phase transition when going from liquid to gas making it excellent for thermometer calibration.

However the ferromagnetic to paramagnetic (or non-magnetic) phase transition is a 2nd order transition. This means that the decrease in the magnetization of the metal is a gradual and continous thing. It's not like the the metal goes from completly ferromagnetic to paramagnetic over the course of a few degrees.

Perhaps you could find a salt with a specific melting temp and use that.

greg
 
You can use pyrometric cones to check the accuracy within about 25 degrees. Pyrometric cones
Googling "Orton Cones" will provide a host of places to purchase. I do this periodically with a 5-cone array. Set them on something like a piece of SS foil or steel, not directly on the floor of the furnace.
 
hardheart said:
maybe you could do like gregorio suggested, table salt melts at 1474
Click to expand...

Pure sodium chloride melts at 1473F, but common table salt probably melts lower, especially the iodized variety. Impurities (introduced or native) cause a phenomenon known as "melting point depression". How much lower is dependant on both the impurity and amount. I don't know what the actual depression is for iodized table salt, but sometimes a small impurity can cause significant lowering of MP.

If you use salt, use non-iodized and try to get it as pure as possible.
 
The book Tool Steels Simplified has a method where you use to melting point of a certain brass, well actually the point at which it starts to solidify.


Can't even imagine doing this to the inside if my HT'ing oven:eek:
 
I believe you melt the brass in a crucible then remove from oven and insert your thermo couple and when the metal starts to solidify the temp will remain constant for a brief period what this transformation occurs. At that point you should read the specified temp for that brass. I guess then you need to melt out the thermocouple. Pain in the kister

The salt thing does sound promising, but, I believe I will get some of the pyrometric cones. That sounds like it will work fine. I guess I should have titled the thread how to check HT oven temps. Sorry. But, hey I did learn a couple things. I do appreciate everyones help sand info. Jim


Fitzo, what cones should I use and should I use the fasted ramp scale as my oven goes to 1500 in less than 15 min? I would assume I need the 014- 016 to dial in around 1500 but you said 5 cones. Care to give me a small tutorial. Thank you
 
Jim, if you can't ramp your kiln at the rates specified, then I wouldn't use the cones. I use programmed rates.

I use 5 cones because I want to see at least one cone that stands totally unaffected by the heat. Cones are "interpretive", and you have to get used to them. So I want extra data. I "overbracket" the range. Two will puddle completely, one will slump, one droop at the very tip, one stand proud. 016-012 cones. Full ramp to 1250 then 108*F/hr after that to hold point at 1500 20 minutes. Then I open the kiln and yank the cones.

Still, the cones will only put you in range to 20-40 degrees, and it sounds like you want a really accurate number.

Personally, I use a second thermocouple/meter through a couple extra holes I drilled and periodically check with the cones as a teritary monitor. Simple paranoia. :) I got burnt a number of years ago and only discovered my controller thermocouple's performance had degraded by the HRc of the blades and was reading higher than actual. It took me three blades to figure out my furnace had drifted 100F. Since then I monitor closely, and expect two probes to match within 20*F. No two probes read the same, even in the same position. I use only Omega probes and replace them when they don't match anymore.

Added: here's a cone chart, with their example. Their cone pic is an ideal, and it seldom comes out exactly that pretty. http://www.bigceramicstore.com/Information/ConeChart.html
 
Thank you. I don't want or need perfection. I just want to be sure I am within say 20 degrees or so. I could do my own ramp by just kicking the set point up 18 degrees every 10 minutes for 108f a hour. I now have a second PID and another thermocouple. so I will also set up so I can check that way. Thanks to everyone for the info Jim
 
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