NGH
Mechanical
- Mar 3, 2005
- 3
Hello fellow members,
I don't post here very often, but I have a question that I would like to ask regarding the elastic behaviour of austentic materials, and in particular their yield point, and their place within the pressure vessel design codes.
In the ISO EN 13445-3 and or the PD 5500 (formerly BS 5500) the calculations utilise a material factor 's' which is 1.1 for austenitic materials and which is 1.4 for carbon steels.
The PD 5500 generally covers the 304, 316, 321 and 347 austenitic materials, but would it be correct to assume that other austentics could also be calculated for from the given formulas?
And more precisely, I am assuming that the 's' factor of 1.1 for austentics is for those materials in their annealed conditions?, but what are the implications for an austenitic material that has has a level of cold working imparted during its mill manufacture, to achieve higher value mechanical properties. In the case of such cold worked austenitics, surely the yield point shifts and the plastic range reduces, and in that case could a different material factor 's' for such a material be implied, i.e. a factor somewhere above the current 1.1 but still most probably below the 1.4 (for carbon steels)?
Other than carrying out exhaustive testing and validation, does anyone know of any papers, or research that has been carried out to ascertain such a revised figure.
Thanks in advance and regards
NGH
PS The intended application is for a cylindrical pressure vessel that is only loaded with external pressure, it does not contain any fluids, gases, nor does it feature as part of any permanent installation. The reference to and use of the PD 5500 is a 'best practice' attitude and not a legal requirement in this case.
I don't post here very often, but I have a question that I would like to ask regarding the elastic behaviour of austentic materials, and in particular their yield point, and their place within the pressure vessel design codes.
In the ISO EN 13445-3 and or the PD 5500 (formerly BS 5500) the calculations utilise a material factor 's' which is 1.1 for austenitic materials and which is 1.4 for carbon steels.
The PD 5500 generally covers the 304, 316, 321 and 347 austenitic materials, but would it be correct to assume that other austentics could also be calculated for from the given formulas?
And more precisely, I am assuming that the 's' factor of 1.1 for austentics is for those materials in their annealed conditions?, but what are the implications for an austenitic material that has has a level of cold working imparted during its mill manufacture, to achieve higher value mechanical properties. In the case of such cold worked austenitics, surely the yield point shifts and the plastic range reduces, and in that case could a different material factor 's' for such a material be implied, i.e. a factor somewhere above the current 1.1 but still most probably below the 1.4 (for carbon steels)?
Other than carrying out exhaustive testing and validation, does anyone know of any papers, or research that has been carried out to ascertain such a revised figure.
Thanks in advance and regards
NGH
PS The intended application is for a cylindrical pressure vessel that is only loaded with external pressure, it does not contain any fluids, gases, nor does it feature as part of any permanent installation. The reference to and use of the PD 5500 is a 'best practice' attitude and not a legal requirement in this case.
