Heat treating and visual observation

AVigil

AVigil

Adam Vigil working the grind
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Feb 17, 2009
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Doing my homework and research on heat treating I am reading my "Seco/Warwick Heat Treating Data Book 9th edition" and came across this bit of information.

Pg 57 Heat For Hardening

"According to tests made by the Carpenter Steel Company in the Service Bulletin, Volume 2, the center and surface of work reach the furnace temperature at the ssame time and accordingly the best method of determining time required to heat for hardening is by visual observation of the work actually coming up to heat, observing the following precautions....."

You can read the precautions which discuss thermocouple placement, judging temperature of actual work and time.

Considering the discussion on heat treating I thought some might like to read about it.
 
I have a hard time seeing the decal. and recal. in anything with lower carbon than 1070. In Aldo's 1084FG and 1095, it might as well slap me in the face, it is so apparent. I have yet to open my kiln and "catch it in the act" yet... so for now I place my trust in the thermocouple.

Rick
 
That is the thing. If you read the precautions they say where to place the thermcouple and to look at the object, not through the peep hole but actually open the door a bit and look at the metal being hardened to determine it coming to heat.

It seems they are using the thermo couple but actually looking at it is "the best method method to determine the time required to heat to hardening". So just leaving it to the thermocouple they have found is only part of it and an actual visual determination should be made."

So does anyone here follow that recommendation from the heat treating data book?

I know the best cooks never rely solely on time and temperature and always look at the cake to see if it is done:D
 
Use all the methods you have at your disposal. I have the thermocouple for a general temperature guideline, Then I make sure the material is up to the same color as the inside of the forge hence it will be about the same as the TC and make sure it is the right color for the temp expected. Then just as an added insurance I do a magnetic test. Once in a while I will put a 1500f tempilstick tablet in the forge to verify TC temp.
 
I wonder how hard it would be puting a window in the door of a kiln. I don't like opening the door and letting air inside. It is hard on the elements. How I compensate is setting a pre-soak for a few minutes to allow the piece to equalize before ramping up to the quench temp. For instance, even my 1084FG sits at 1425F for 5 minutes before moving up to 1500F. My steels are simple enough that soaks can be ballpark. I was VERY aware of the visual aspect when using the open forge to heat treat. My room is set up such that I have complete consistent control of light.

It'll be cool to hear what the nerdy guys have to say about it.:p:thumbup:
 
A C Richards said:
..Once in a while I will put a 1500f tempilstick tablet in the forge to verify TC temp.
Click to expand...

That is exactly what I did to put my mind at ease about the accuracy of my kiln.

I set several different tabs on a plate together and would let it ramp to each and check...

1300F
1400F
1450F
1500F
1550F
1600F

One thing I learned is that radiant heat from the coils spikes the temperature faster than the thermocouple can relay to the controller.

Rick
 
Interesting, I have used the templac crayons at work before but not seen the tablets, where would one buy those.

Richard
 
IIRC I got mine from either MSC or McMaaster Carr. I will have to look and see if I can find them again.
 
i make sure to have a shield from the elements in the kiln to keep them from spiking the blades. i have also seen the steel in the kiln dec. and rec. (the steel shadow dance :) ) i now do it when HT of my clay coated blades jsut to keep it as close as i can to aust. temp

i do want to get a 2nd pryo setup even if its jsut to test now and then the kiln and whennn i need to swap elements to make sure im still hitting my temps be it 1500 or 2000f that ad i want a back up kilon and grinder (oo if only i had a real job to pay the bills )


edit to add that if you want a window it could be done like any ceramics kiln with a tapered hole and tapers firebrick plug (the hole is not more then about 1 inch on the small end) i to think you could make a 3 glass multi pane window of pyro glass
 
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I have not been able to find the tablets. Looks like they are no longer produced. The liquid does look interesting though.
 
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