Elevated heal lot mechanical properties 1

[kpl012]

Is there any data suggesting the higher heat lot properties at room temp. will parallel the curve of the mechanical properties of said material at temperatures ?

 

[EdStainless]

For what material?
Up to some temp, yes it will just be an offset.
As the temp gets higher the values will converge.


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Plymouth Tube

 

[kpl012]

The material is CRES316L.

 

[redpicker]

kpl012,
It sounds as if you are assuming that the mechanicals (say, yield strength) reported on the MTR are the same for all pieces of the (heat) lot. This is an incorrect assumption and can lead you into trouble.

The mechanical properties reported on the MRT simply demonstrate that the material has been tested and the results meet the mechanical property requirements of the specification. It is quite possible (nearly guaranteed) that some material in the lot will have higher and/or some material will have lower properties than reported. What you can be sure of, however, is that all the material in the lot meet the specification requirements they are certified to meet (provided the supplier has adequate process control).

Consider, for example, a processor has a testing practice to test the first and last of the run. Furthermore, let's say that this manufacturer knows that his process will result in +/- 2000 PSI in yield strength. If both of his tests are 5000 PSI above the minimum and/or below the maximum, he knows all the product meets the requirements. Now, in the real world, these values be different, but you can see why the manufacturer may be fully aware that some of the product in the lot is significantly below what is reported on the MTR, but not be concerned (if, as in the hypothetical above, he knows it will all meet the requirements of the specification it is certified to meet). There really is no way for the manufacturer to test and report the lowest (or highest) test result in the lot.

rp

 

[kpl012]

In my case these were certs for flanges made to ASME A182. Wouldn't the flanges retain the elevated properties on the certification papers ?

 

[EdStainless]

It depends on why the properties are higher.
If it is because of the composition (C or N) then it will be higher at elevated temp.
If the properties are higher because it is under annealed then it will drop as the temp gets higher.

Never bet on having anything higher than the minimums, unless failure has no risk of injury and no cost.

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Plymouth Tube

 

[kpl012]

Great. Thanks Edstainless.