Thermal Expansion

How can Sub-zero treatment work with this, can this minimized the thermal expansion during high temp?

Can anyone help me understand what Sub-zero treatment really is and its application?

https://b2.boc.com/catweb/CATweb.nsf/noteid/832EBF350F5C9B00802572C1004AAF48/$file/SpEd_SubZeroTreatment_steels_1.pdf

Would you specify what problems you are encountering? Can't put the part in the unit? Part expands to much causing failure?

You should consider in the dimensioning the thermal expansion so that at working temperature the function will be obtained.

The subzero is used to control retained austenite in the steel (or rather convert these into martensites)

In your case, the welded structures, you are not likely to aim for the martensitic structure, nor they are likely to be good for you.

This conversion to martensite are not likely to have any significant effect on the coefficient of thermal expansion. In fact you are not likely to get a material with zero coefficient over a long range you are aiming for ( a few become zero momentarily or over a small range)

As mentioned, design your equipment to accommodate the expansion (may be put some flexible component, work with larger clearances with some sealing ...)

We face a similar problem with a UHMWHDPE component of a biomedical implant. The component has to be machined at -25ºC to get the necessary finish and has to fit in an assembly to 10 μm accuracy at inside body temperature (Max. 40ºC). Plastic has about one order of magnitude higher expansion coefficient of thermal expansion.

We just compensate during machining and allow the component to expand to the required dimension in use.

Hi,

the subzero treatment has a minor effect on thermal expansion if there is a lot of austenite after quenching.

Austenite has a TCE of 17ppm/K and martensite,perlite, ferrite between 11 and 12ppm/K

RHABE