Affect of temperature on Steel

[beretta24]

I have an application where a 316 stainlesss part is being used to maintain a compressive load on an assembly. During manufacturing, the SS part was heated to a point where the part relaxed and no long maintained a load on the assembly.

My question is at what temperature will the steel become adversely affected by the heat? Will it begin to relax prior to the annealing temperature since it is loaded? I did a some digging and it seems to be common practice to heat steels (to temps lower than the annealing temp) to aid in forming processes. I would view heating a part that is under load to be somewhat analogous.

In the end, I need to set a maximum allowable temperature for the process.

Thanks.

 

[EdStainless]

The strength for any metal will start dropping as soon as you begin heating it. You can find tensile property vs temperature curves for most common alloys. If your load is anywhere near the yield strength then even modest heating will result in relaxation.


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[metengr]

For 316 stainless material, it appears that the allowable stress value changes at about 400 deg F (this information is from ASME B&PV Material Tables).

So, if you can limit the temperature to 300 deg F or less, and the tensile stress applied to maintain the compressive loading does not exceed the yield stregnth of the stainless, you should be ok.