Hardness of P91 Material weld

By shivar80 Date 02-12-2008 11:32

1)What should be the hardness of P91 Material weld & its heat affected zone?If mentioned in any code please let me know the code & clause no.
2)What is effect of Arsenic,Tin & Antimony content on physical properties of P91 Material & what should be its percentage value? if any reference please let me know.

By chall

Date 02-12-2008 13:08

ASME B31.3, Table 331.1.1 (Requirements for Heat Treatment) specifies a maximum Brinell Hardness value of 241 for P5B materials (which P91 grade material is) following PWHT. PWHT is required for all P5B materials if your code of construction is any of the ASME codes.

I don't know what the matallurgical effects of the elements you listed are; however, the composition limits, from ASME Section IID, SA335-P91 are not specified.

Charles

By js55

Date 02-12-2008 14:24

Those are typical J Factor(base metals) X Factor (filler metals) elements that determine a materials susceptibility to reheat cracking or temper embrittlement. typical of CrMo type, and other low alloy type materials.
If you google X Factor, J Factor, Watanabe, or Bruscato (the developers of the formulas) you will find much information.
These Factors are formulas that result in a number that can be limited by specification. Often in the neighborhood of 15.
Also, the WRC Welding Research council has a really informative bulletin on Temper Embrittlement, discussing what metllurgically takes place with these elements and the suceptible temperature ranges.

By js55

Date 02-12-2008 14:26

Temper embrittlement begun as more of a concern with vessels since the longer heat treat times left the materials in the susceptible ranges for the phenomenon. In the last decade or so the Watanabe/Bruscato formulas have found its way into piping specifications as well.