How this calculator works
Each empirical index weights alloy elements differently. IIW and its silicon modification are not interchangeable with Japanese Ceq or Pcm. Pcm is commonly used for low-carbon steels. Select the formula specified for the material and procedure; hydrogen, thickness, restraint and heat input also affect cracking.
Formula
IIW=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15; modified IIW=IIW+Si/6; Japanese Ceq=C+Si/24+Mn/6+Ni/40+Cr/5+Mo/4+V/14; Pcm=C+Si/30+(Mn+Cu+Cr)/20+Ni/60+Mo/15+V/10+5B.
Worked example
For C=0.20, Mn=1.20 and Si=0.30 wt%, with all other inputs zero, IIW=0.40, modified IIW=0.45, Japanese Ceq=0.4125 and Pcm=0.27.
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Frequently asked questions
Should I enter 0.002 or 0.20 for 0.20% carbon?
Enter 0.20. All fields and indices use the mass-percentage basis of the published formulas.
Does a lower value guarantee crack-free welding?
No. These indices only describe part of the susceptibility. A qualified welding procedure must address the full joint and process.
Why can I not solve boron using IIW?
IIW has no boron term, so its value does not determine boron content. Pcm includes boron.