Dear Santosh,

In case of solution heat treated AISI 316L yield point at room temperature is ~220 MPa and tensile strength is ~620 MPa. To calculate maximum permissible stress you need to define Factor of Safety.

In case of solution heat treated AISI 316L yield point at room temperature is ~300 MPa and tensile strength is ~650 MPa. To calculate maximum permissible stress you need to define Factor of Safety

Look at attached stress-strain curve. Red is stress.

Yes dear

You asked what the maximum permissible stress is,

Maximum permissible stress is a design practice, this means it is a relative value depend on three factors;

•         The production and treatment condition of the 316L to be used (i.e. annealed, cold work, cast…),

•         Environment parameters ( temperature and type of exposed environment), and

•         You, as the design engineer who going to estimate the value of permissible stress 

Maximum permissible stress = Yield strength / factor of safety

Now, Stainless Steels do not typically show Yield strength Point, and the change from elastic behavior to permanent plastic deformation is not usually easy to detect. Thus , the yield strength for stainless steels is usually taken as the stress which will produce a 0.2% permanent strain (offset). This value must extracted in terms of the design temperature and for specified treated type of SS316L. 

Depend on your experience as engineer you should estimate the factor of safety which defined as how far your design away from the yield strength Point. The safety factor in some critical design reach 4 but in most cases 1.25

When you estimate the permissible stress care should be taken whether the SS316L is subjected to stress corrosion cracking induced environment, if so you should consider a comparison between the estimated permissible stress and the threshold value for stress corrosion cracking so you should do farther increase in safety factor to bring the permissible stress below the stress corrosion cracking threshold value.

Finally it is difficult to see on value for the permissible stress of SS316L done by two engineers.

Thank you a lot

Yers, you need to define a factor of safety. Same if the question is also for temperatures above room temperature (Tr). Then creep appears (and also creep-fatigue interactions depending on the working conditions) and you have to take a safety factor on the minimum stress giving 1% deformation or rupture in e.g. 100,000 hours. There are materials standards for the stresses (yield, tensile strength at Tr / for creep rupture in x hours at high temepratures, etc...). Also, design codes give safety factors.       

 dear prof Guibert Crevecoeur, thank you for your addition that completed the idea 

my great respect