CF8M stainless steel is the most widely used US standard austenitic stainless steel casting grade. Its equivalent type is cast 316. From the name CF8M, the letter "C" means the alloy is mainly for the purpose of corrosion resistance. The letter "F" is the approximate location on the iron-chromium-nickel (FeCrNi) ternary diagram.
ASTM A351-2018. ： 600. ： Designation: A351/A351M − 18Standard Specif i cation forCastings, Austenitic, for Pressure-Containing Parts 1This standard is issued under the f i xed designation A351/A351M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision
SS316 is defined in ASTM A240 and ASTM A276, it's for plate, sheet, strip or stainless steel bars. Another grade is named as F316, which is from ASTM A182 for Forged parts only. TP316 will be found in ATSTM A376 for pipe only. If you want to buy castings, Pls indicate CF8M as material, otherwise you can adopt SS316.