martensitic stainless steel spring stress at low temperature 2

[dparndt]

Hi,

I'm doing stress analysis using solidworks on a martensitic stainless steel spring that is operating cyclically at -30C ambient temperature. The analysis at room temperature results in a max stress of around 80 ksi. When I apply a temperature load to the analysis, the resulting max stress is around 100 ksi. Does this result make sense? Is this due to thermal stresses in the part?

Thanks,

-Dave

 

[israelkk]

What kind of spring?

 

[CoryPad]

Dave,

I don't think this is due to thermal stresses. Can you share the constraints and boundary conditions for the part/assembly? This may be due to higher elastic modulus at lower temperature. Can you look at the software's material property database and see what is has?

 

[EdStainless]

Do you have a martensitic stainless that has any usable ductility at -30? Wouldn't surprise if this was not well below the DBT.

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Plymouth Tube

 

[dparndt]

Its a machined spring like the ones shown here:

http://www.taylordevices.com/machined-springs.html

It is made of custom 455. There is no temperature vs. elastic modulus data defined in solidworks right now. I guess I probably posted in the wrong forum because it seems the difference is likely due to how I am simulating rather than an effect due to material properties. I have one end fixed and I'm deflecting the other end by a fixed amount.

Thanks for the help

 

[EdStainless]

C455 is not a martensitic stainless.
It is a martensitic precipitation hardening alloy.
I am still not sure that it will have usable ductility at -30.

You should get some temperature dependent properties to use.

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Plymouth Tube

 

[tbuelna]

According to MIL-HDBK-5, the Fty properties of Custom 455 H950 cond. increase about 8 percent going from RT down to -100degF. (ref. rev. J, p.2-143). Elongation rate remains fairly constant over the same range, about 10%.

Ductility would not appear to be an issue at -30degC.

There's no data for E other than RT values (28.5x10^6 psi).

Hope that helps.
Terry