Carbon Equivalent of ABS Grade A Shipbuilding Steel Plates
- Apr 20, 2026
Knowledge
Carbon Equivalent of ABS Grade A Shipbuilding Steel Plates
1. Chemical Composition (wt %)
| C | Mn | Si | P | S | Cu | Cr | Ni |
|---|---|---|---|---|---|---|---|
| ≤ 0.21 | ≤ 0.50 | ≥ 0.50 | ≤ 0.035 | ≤ 0.035 | ≤ 0.35 | ≤ 0.30 | ≤ 0.30 |
2. Carbon Equivalent Calculation Formula
Using the IIW formula: Ceq = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15 (%)
3. Typical Calculation Examples
Upper limit values:
C = 0.21%, Mn = 0.50%, with the content of other alloying elements (Cr, Mo, V, Ni, Cu) approximating 0.
Carbon equivalent calculation: Ceq ≈ 0.293%.
Additional notes:
For ABS Grade A standard-strength shipbuilding steel plates, the carbon equivalent (Ceq) is not typically a mandatory requirement in ABS classification society specifications. However, taking into account common practice in the shipbuilding industry, welding processability requirements, and the actual test data provided in the steel mill’s certificate of quality, the typical control range for the carbon equivalent of this steel grade (calculated using the formula recommended by the International Institute of Welding (IIW)) is 0.30%–0.38%.
4. Cold Cracking Sensitivity Coefficient (Pcm)
ABS also commonly uses Pcm to assess the weldability of standard-strength ship plates: Pcm = C + Si/30 + Mn/20 + Cu/20 + Ni/60 + Cr/20 + Mo/15 + V/10 + 5B (%)
ABS Grade A generally requires Pcm ≤ 0.26% to 0.28%.
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