astm a447 vs. astm a297 grade hh

[49078]

Hello all,

I am still learning my nomenclature for stainless steels, especially castings, but can anyone tell me the difference between ASTM A447 Grade HH-2 and ASTM A297 Grade HH-2?

Our current line uses the 297, but on older drawings we have the material labelled as A447, and on some other drawing just labeled as Grade HH.

Thanks in advance.

 

[andyenergy]

http://www.key-to-steel.com/Articles/Art25.htm

http://www.astm.org/cgi-bin/SoftCart.exe/DATABASE.CART/REDLINE_PAGES/A297A297M.htm?E+mystore

http://www.astm.org/cgi-bin/SoftCar...org/DATABASE.CART/REDLINE_PAGES/A447A447M.htm

Seems to relate to whether the castings are to be used in high temp service or not.

 

[arunmrao]

Nominally both the specifications are for 25%Cr and 12% Ni class of materials.

ASTM A447 Grade HH 2 refers to alloy having high high limiting creep stress but which may develop low ductility at ordinary temperatures when aged for short periods at temperatures between 1350 and 1500°F [730 and 815°C].

Grade HH normally refers to ASTM A297 standards.