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martensitic stainless steel spring stress at low temperature
2

martensitic stainless steel spring stress at low temperature

martensitic stainless steel spring stress at low temperature

(OP)
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

RE: martensitic stainless steel spring stress at low temperature

What kind of spring?
 

RE: martensitic stainless steel spring stress at low temperature

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?

RE: martensitic stainless steel spring stress at low temperature

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

RE: martensitic stainless steel spring stress at low temperature

(OP)
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

RE: martensitic stainless steel spring stress at low temperature

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

RE: martensitic stainless steel spring stress at low temperature

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

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