T/P 23 & ASME Code Case 2199
T/P 23 & ASME Code Case 2199
(OP)
I have managed to virtually purloin a copy of the original code case, but I know there have been a series of successive versions, up to 2199-5 if I am correct.
My question is whether these revisions are merely renewals or revisions; and if the latter, what was the nature of the changes? I saw a murmuring in CCJ that chemistry was revised.
My question is whether these revisions are merely renewals or revisions; and if the latter, what was the nature of the changes? I saw a murmuring in CCJ that chemistry was revised.





RE: T/P 23 & ASME Code Case 2199
RE: T/P 23 & ASME Code Case 2199
(1) Boron activity is predicted from the Ellingham diagram for nitrides (if anyone has a good sample I would love to get it).
(2) Boron is known to have a powerful effect in lowering free energy at grain boundaries. In the case of CSEF steels, it controls M23C6 carbide growth and coarsening, which is detrimental to creep properties.
(3) Ti would be added to T23 because of its greater affinity for N. Some N is unavoidable in any steel, sometimes it is added intentionally. Only free B is 'effective', so it needs to be protected from N.
(4) I suspect B also acts in T23 to suppress ferrite formation (as in HSLA steels), thereby promoting bainite. This would be consistent with your comments re: low hardness in T23.
RE: T/P 23 & ASME Code Case 2199
RE: T/P 23 & ASME Code Case 2199