My task to do is to generate a compression force between two plates when they rise it's temperature from ambient to 480°C
This  300 mm diameter round Sae 1010 plates 38 mm thick, will hold a stack of  about 100 each  Sae 1070 1mm thick to be flattened .
This, can be called sandwich, will be hold by a 40 mm round  SAE 4140 threaded bar  heat treated as a 12.9   grade bolt.
To build up a increasing compression , I intent to put a spacer over one plate and under the nut that will tighten all the array  , this spacer shall be of a material with a different thermal expansion from  the others components.
I thought on a aisi 304 hollow bar as it have a thermal exp coefficient about 17E-6 micro mm/meter/°c
 and the carbon and alloy steel had about 10e-6 .
My concern is about the behavior of all this array at the 480 C temperature, it will be about 4 hour since this temp is reached.  
The task to cope, is to avoid a loss on the compression, so all the 1070 plates are gathered side by side , so they will last flattened when this force is released,  of course that it will happen after the eat treatement.
Any comment will be granted.