MAXIMUM VANADIUM CONTENT IN ASTM A333 Gr.6

[GabrieleB]

Vanadium(V) with Niobium(Nb) is usually used to have fine grane and solubilization properties on carbon steel. The common limit used for both is 0,15%. I need to be compliant with a specification that limits the Vanadium content belove 0,05% while a Vendor offer me a Carbon steel ASTM A 333 Gr.6 with Vanadium at 0.07%. Is that acceptable for a low temperature carbon steel. Why the specification asking for such low limit?

 

[GabrieleB]

P.S. Sorry for the missing information. The material shall be also NACE compliant (Sour Service application).

 

[SJones]

End user specification restrictions are usually aimed at achieving good weldability such that issues with installation contractors do not arise. Even more so when weld zone hardness maxima will apply as in ISO 15156-2.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[GabrieleB]

For my experience since the thickness to weld is 12.7mm, welding I think is not critical. Moreover Vanadium below 0.15% is not an issue for welding execution as far as I know. Vanadium give fine grane, solubilization and also beneficial effects on thoughness. I have seen also that on ASTM A 333 there is not maximum limit for Vanadium content, so I think that is not considered critical far that material. If anyone has other experiences with that material let me know. Thanks!

 

[SJones]

If that is your view, try putting it to the owner of the specification and see if they concur.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[metengr]

Notch toughness acceptance is the main concern with this material, especially after PWHT, and so is meeting the minimum tensile strength. ASME SA 333 Grade 6 provides no stated maximum value for vanadium or other microalloy additions. This means the Purchaser can set maximum limits for these other alloy additions to ensure meeting strength and notch toughness requirements.

Since vanadium is a potent strengthener and will affect low temperature notch toughness behavior, the Purchaser is purposely limiting this content and other microalloy additions. Grain refinement is provided by aluminum, per specification.

 

[stanweld]

If the 333-6 has not also been made to fine grain practice through additions of Aluiminum, notch toughness in the HAZ, when subject to PWHT, will be adversely affected.

 

[Guest102023]

In addition to Stanweld's point, my only potential concern is stress relief cracking in situations of high residual stress and/or restraint. Thicker sections (>>12.7mm) are at greatest risk.

This could be a case of the specification writer trying to anticipate every potential metallurgical issue by writing such a tight specification that he shrinks the cost/availability window.