KEVOS® MAKEOS · Fabrication
Carbon Equivalent and Weldability
What carbon equivalent does this steel have, and does it suggest preheat?
Carbon equivalent (IIW) and Pcm (Ito–Bessyo) from a steel’s chemical composition, with commonly cited weldability guidance.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Carbon | % | Carbon content from the mill test certificate (weight %). |
| Manganese | % | Manganese from the certificate. |
| Silicon | % | Silicon from the certificate (used in Pcm only). |
| Chromium | % | Chromium from the certificate. |
| Molybdenum | % | Molybdenum from the certificate. |
| Vanadium | % | Vanadium from the certificate. |
| Nickel | % | Nickel from the certificate. |
| Copper | % | Copper from the certificate. |
| Boron | % | Boron from the certificate (used in Pcm only). |
Method and formulas
- CE(IIW) = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15.
- Pcm = C + Si/30 + (Mn + Cu + Cr)/20 + Ni/60 + Mo/15 + V/10 + 5B.
- Example: the default chemistry gives CE = 0.43933 and Pcm = 0.2715.
Limitations
- Preheat also depends on thickness, heat input, hydrogen level and restraint; the bands are screening guidance, not a procedure.
- Pcm is intended for low-carbon steels (C below about 0.18%).
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Screen a steel for welding preheat
- Compare mill certificate chemistry
- Choose a welding procedure category
Who it is for
- Welding engineers
- Welding supervisors
- Quality inspectors
What you get
- Carbon equivalent CE (IIW)
- Pcm
- Weldability band
Interpreting the result
- Commonly cited guidance: CE up to about 0.40 is readily weldable; 0.40–0.60 usually needs preheat and low-hydrogen practice; above about 0.60 needs careful procedures. Determine preheat with AS/NZS 1554.1 or your welding procedure.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1431–1449. Topic reference; no source tables or recommended settings are reproduced.
- AS/NZS 1554.1 Structural steel welding (preheat determination); International Institute of Welding carbon equivalent
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