High temp creep 1.25Cr-.5Mo

[MTRandCo]

I need to know what limits to place on contaminants for 1.25Cr-.5Mo steel at 965F operating to limit or prevent long term high temp. creep. I found a thread Thd367-58995 by "Maui"
providing limits for 2.25Cr-1Mo. See the following excerpt:

To ensure that the steels resist such embrittlement, restrictions are placed on above elements for both base metals and weld metals. For e.g. to qualify a LA steel plate like say SA387 Gr22 Cl 2 for such service, very stringent requirements on the material chemistry are to be met. These are defined as the J and X Embrittlement factors with
J Factor= (Si+Mn) x (P+SN) x 10^4 </=160(elemnts expressed in wt%)
and
X factor=(10P+5Sb+4Sn+As) </=15 (elements expressed in ppm)

I have since been told that the J factor typically applies to base metal and the X factor applies to weld metal. Weld metal meeting X factor is attainable but getting flanges meeting J factor is next to impossible within the time frame I have and is very expensive since each heat must be &quot;wet tested&quot; to determine the Sn content. Any help on this subject would be greatly appreciated.

 

[sayee1]

Typically the J and X factors are used for 2.25 Cr 1Mo and not 1.25 Cr 0.5 Mo. This I am inclined to believe is because of the 1%Mo as against the 0.5 % Mo in your case. These factors are typically used to predict the temper embrittlement charactersitics of a 2.25Cr 1Mo steel. I wouldn't use J and X factors for the type you mentioned unless there is a client requirement for the same. In the same lines note that to study long term creep, step cooling and study of the shift in impact values are also used for the 2.25Cr 1Mo steels.

Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
email: sayee_prasad@yahoo.com
The black holes of nature are the most perfect macroscopic objects there are in the universe: the only elements in their construction are our concepts of space and time.

 

[Maui]

MTRandCo, I believe that the excerpt you posted should be credited to sayeeprasadr, not myself. I did post in the thread you mentioned, but I made no mention of chemistry limits for 2.25Cr-1Mo. I will take credit when I have earned it, but in this case I must defer to sayeeprasadr.


Maui

 

[MTRandCo]

Thank you Sayee Prasad R. My customer has only asked us to pay particular attention to contaminants. Do you know of any guidelines for 1.25Cr-.5Mo to avoid temper embrittlement? I need some literature to present to my customer which will address his concerns.

MTR