Carbon Equivalent Formula

[Dinosaur]

I recently learned that there are more than one carbon equivalent (C.E.) formulas out there. The formulas I am interested in understanding are the AWS and the ASTM versions.

The AWS version includes a term Si/6. The ASTM version includes a term V/5. Can anyone explain the difference? I noticed that ASTM A709 steels contain up to 0.40% Si (some grades even more). The Vanadium content is limited to a much smaller level, typically 0.06% for example. If the silicon content of steel is frequently higher than the limit for Vanadium, then the AWS formula appears more strict.

Is this warranted?

 

[metengr]

Please do not cross post. Thank you

 

[henri2]

Preheat in D1.1 is usually determined from Table 3.2 or Annex M (A514, A517, A709, and A710). Another option is to use equations for CE in Annex XI. In Annex XI there two methods; one method based on HAZ hardness, and the other based on hydrogen control.

One draw back about using Annex XI for determining preheat is that if the preheat/interpass temp is lower than that required for prequalified WPSs, qualification testing must be performed. Ref: D1.1 Section 3.5.2