Bolting with X6NiCrTiMoVB25-15-2 1

[Garlik]

Hi all,

Has anyone experience with bolting material X6NiCrTiMoVB25-15-2 (austenitic)? This is used for tightening pressure boundary parts of a valve.
Up to which temperature is possible to use this material and for how long?
I am afraid about the possibility of having intergranular corrosion and then a failure.

Thanks and regards,

 

[CoryPad]

EN 10269 shows creep rupture strength of 132 MPa for 100 000 hours exposure at 650 [°]C.

 

[Garlik]

Thanks CoryPad.
I knew that... and I also know about values of 200.000 hours according a VdTÜV.
But what happens with the embrittelment of the material after a long exposure at this high temperatures? If there is a load cycle, bolts might break, right?
What materials are used for bolting at high temperatures (more than 600°C)? Inconel might be an option. What else?
Thanks.

 

[CoryPad]

I cannot speculate on your environment and potential embrittlement.

For high temperature bolting materials, options include the following from the ASME Boiler and Pressure Vessel Code:

UNS S31600 (SA193 B5) 650 [°]C
UNS S33000 (SA193 B8M) 825 [°]C
UNS S34700 (SA193 B8C) 825 [°]C
UNS S32100 (SA193 B8T) 825 [°]C
UNS S30500 (SA193 B8P) 825 [°]C
UNS N02201(SB160) 650 [°]C
UNS N06002(SB572) 900 [°]C
UNS N06600(SB166) 650 [°]C
UNS N08810 (SB408) 900 [°]C
UNS R30556 (SB572) 900 [°]C
UNS N06625 (SB446) 650 [°]C
UNS N08800 (SB408) 825 [°]C
UNS N10003 (SB573) 725 [°]C
UNS N10276 (SB574) 700 [°]C

A few options from the aircraft engine industry, SAE AIR4923:

UNS N07718 (AS7467) 650 [°]C
UNS N07001 (AS7471) 815 [°]C
UNS S07041 (AS7469) 870 [°]C
UNS S66286 (AS7477) 650 [°]C

 

[Guest102023]

Good heavens, what is X6NiCrTiMoVB25-15-2? Sounds obscene ...

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[CoryPad]

You may know it as A286 or UNS S66286.

 

[XL83NL]

Wouldnt that be the equivalent of ASTM A453 Gr 660

 

[CoryPad]

Yes