Need help w/carbon equivalency determination 1

[KernOily]

OK here's a dumb question from someone who usually works in the oil patch, not metallurgy.

I need to calculate a carbon equivalent so that I can show that a steel proposed for use in a tank will meet UL 142.

There are several formulae one can use to calc the carbon equivalent %. Which is the one to use? None of my references have this info (Marks dropped the ball on this one... at least I can't find it in there!) and a web search produces at least five different eqns for carbon equiv %.

Thanks for your help guys! Pete

Thanks!
Pete

 

[metengr]

The most common CE formulas to evaluate weldability for fabrication depends if the metal is an alloy steel or modern carbon steel. Here are both common CE equations;

for low alloy steel, elements are w% amounts;

Ceq = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15


for modern low carbon steels, elements are expressed in weight percent amounts;

Ceq = C + Si/25 + (Mn+Cr)/16 + (Cr+Ni+Mo)/20 + V/15

 

[KernOily]

Thanks for your reply. The steels in question are are SA36 and SA516-70. Which category would these steels fall into, in your post? Thanks! Pete

Thanks!
Pete

 

[KernOily]

Also - the first eqn you presented is the IIW eqn. What is the name or reference for the second one? Thanks! ! !

Thanks!
Pete

 

[metengr]

74ELsinsore;
Use IIW for comparison with SA 36 to SA 516 Grade 70. These are considered C-Mn low alloy steels, and the IIW is used by AWS and ASME B&PV code for base metal weldability comparisons.

The second CE equation was referenced from a Welding Research Council Bulletin.

 

[KernOily]

Thanks metengr - you're a stud Exactly what I needed to know. Nice timely response. You get two stars THanks ! ! !

Thanks!
Pete