Conducting Electrode Material and Pre-treatment of Electrodes Experiments

[HTwoGo]

You have to dwell them at temperature between 1060-1120 C for at least 30 mins and back down to just bellow 1000 C for 30 mins and do this cycle 4-5 times to anneal them properly. Your furnace sounds like it will do the job. Remember to let them cool inside the furnace without opening the door after the completion of the process.

?okay I have run two test pieces, of 304 S/S plate, one I ran the protocol above at 1100 C and I will know the results tomorrow morning.
The other I followed a more convention protocol i.e. quench from full heat 1100C per this link? http://www.azom.com/details.asp?ArticleID=965#_Heat_Treatment
The quenched plate suffered badly from distortion and (probably my carelessness) if it proves the better protocol I will need to somehow control this, perhaps a sandwich between some slabs of 310 S/S, this I have done before but in a production setting with controlled atmosphere.
Once I have both samples ready I will be passivating in 20% nitric acid at 50-60C for 30 min.

Best, HTwoGo

[Duranza]

Remember that they need to air cool inside the furnace without opeing the door.. You are not looking to harden them by quenching. The property of the SS has to remain unchanged...

[Davetech]

I wanted to condition some 3 inch square SS plates that I had made. I didn't have plate material, but I had SS tubes, barely noticed by a magnet, so I guess 316. I cut the tubes into 3" lengths, cut a slot down the tube, and pounded them out flat with a heavy hammer.

I knew I had introduced plenty of stresses so I wanted to do a full anneal, but I don't have a suitable furnace. The best I could do was heat them to bright orange with oxy/acetylene and then quickly stick them into a cavity in my casting sand and slap a cover over them to slowly cool.

The problem I ran into was in heating them with the torch. They badly distorted, undoubtably because of uneven heating. So I have a bunch of warped plates that need pounding again.

Thought I would post this so anyone else thinking of annealing plates in this fashion might want to think again, especially if they are nice, flat, store-bought plates.

[Gheller J]

HTwoGo>>>>>

If ur furnace cannot accommodate inert atmosphere annealin>>>dont try it!

Process>

Place tubes in furnace>>>>>purge in Pure Nitrogen / Argon gas>>>donot open furnace after dis

Have leakage gas flowing continuously through the annealin process.

Heat to required temp>>>hold for time of specific grade*

Let the furnace cool 2 atleast 100-150 deg C befor u remove d pipes

Inert gas (leak) has to run till pipes cool of & u open d furnace


Incase u get an oxide coat>>>>ur inert gas wasnt sufficient!>>>>> u'll have to sand d tubes n start all over!

* 304L >>> 1050 deg C for 70 minutes
* 316L >>> 1050 deg C for 90 minutes

d hold time varies on thickness aswell>>>for pipes upto 2mm thick above time's ok!



Gh. J.

[HTwoGo]

?I have decided to abandon this trial until I can get some sort of controlled atmosphere in place, the contrast between the exposed an protected surfaces of the slow cool sample is so much I must conclude there would be little worth knowing from going any further.

Best, HTwoGo