Piston ring heating

[Gordon]

What temperature do you use for heating piston rings? Trimble says 1400° Others say 1100° and I just read Chaddock says 950°
I have an old kiln which means that I can control the temperature. What have others been using?

 

[stevehuckss396]

I do 1100F for 3 hours. Got that information from a metallurgist who was a guest speaker at one of our metal club meetings. Explained in exact detail why it needed to be that temperature and for that long. Only understood 15% of what he said but I do it that way and have never been disappointed.

 

[Gordon]

Thanks. I have been using 1100° also. I have not paid much attention to the time but the kiln stays hot for a long time and I have always left them in the kiln to cool so it is probably close to 3 hours. I just read the Chaddock instructions and he said that 950° was ideal and anything over 1000° was too much. I just did the last set of rings at 950° and they are not fully annealed and the gap springs back. I have extra rings so I will probably put them back in the kiln at 1100°,

 

[bluejets]

Method I use is to stack a group of cast iron rings together and clamp between 2 end disc washers made of approx. 1/2" thick mild steel.
A through bolt 1/4" holds everything together.
Sit the unit on a house brick and heat to red heat with a butane torch for 15 minutes and let cool naturally.
Works just fine.

 

[kuhncw]

I've been stress relieving rings for three hours at 1100F, then letting the furnace cool overnight. The rings are bare, in a Trimble fixture
and I've seen no problems with scaling at these temperatures.

Chuck