Intergranular corrosion of CN7M (Alloy 20)
Intergranular corrosion of CN7M (Alloy 20)
(OP)
We have been asked to supply some castings in ASME SA351 CN7M (cast Alloy 20), with the following additional requirement:
"Intergranular corrosion test in accordance with ASTM G28A or equivalent"
We have supplied plenty of castings in this material over the years, but never before with a corrosion test requirement.
Is G28A a suitable test for this alloy? If so, what results would you expect? If not, what would you suggest as an equivalent alternative? Would one of the tests in ASTM A262 be suitable?
"Intergranular corrosion test in accordance with ASTM G28A or equivalent"
We have supplied plenty of castings in this material over the years, but never before with a corrosion test requirement.
Is G28A a suitable test for this alloy? If so, what results would you expect? If not, what would you suggest as an equivalent alternative? Would one of the tests in ASTM A262 be suitable?





RE: Intergranular corrosion of CN7M (Alloy 20)
Steve Jones
Materials & Corrosion Engineer
http://www.linkedin.com/pub/8/83b/b04
RE: Intergranular corrosion of CN7M (Alloy 20)
RE: Intergranular corrosion of CN7M (Alloy 20)
TVP: shortly after reading SJones post I reviewed G28 more carefully and discovered N08020.
We are being asked more and more often to supply castings with G28A corrosion testing, presumably because there is no equivalent test for cast material. Our clients have, so far, set different maximum allowable corrosion rates for wrought and cast materials on their spec sheets.
RE: Intergranular corrosion of CN7M (Alloy 20)