What is carbon equivalent (CE)?

Carbon equivalent is a single number that represents the combined effect of alloying elements on steel hardenability and weldability. The IIW formula: CE = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15. Higher CE means harder HAZ and greater cracking risk during welding.

How does CE affect weldability?

CE 0.60: Very poor, special procedures needed.

Are steel grade equivalents exact?

No, equivalents are approximate. While chemical compositions are similar between standards, exact ranges differ. Always verify specific composition requirements from the material test certificate for critical applications.

How is preheat temperature determined per AWS D1.1?

AWS D1.1 Table 3.3 provides minimum preheat based on steel category, thickness, and hydrogen level. Simplified: CE < 0.35 → none; CE 0.35-0.45 → 10-75°C thin, 75-150°C thick; CE 0.45-0.60 → 150-250°C.

What is the difference between CE(IIW) and Pcm?

CE(IIW) works best for medium/high carbon steels (C > 0.18%). Pcm (Ito-Bessyo) is better for low-carbon microalloyed steels (C < 0.18%): Pcm = C + Si/30 + (Mn+Cu+Cr)/20 + Ni/60 + Mo/15 + V/10 + 5B.

Free Engineering Tool

Steel Grade Equivalent & CE Calculator

Cross-reference steel grades across EN, AISI, DIN, JIS standards. Calculate carbon equivalent (CE), weldability, and preheat temperature.

EN / W.Nr. AISI / SAE CE IIW AWS D1.1

Results

Carbon Equivalent CE (IIW)

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Weldability Assessment

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Preheat Recommendation

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Pcm (Ito-Bessyo)

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Grade Equivalents

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Typical Yield / UTS

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EN	W.Nr.	AISI	DIN	JIS	Type	CE

Carbon Equivalent — IIW Formula

Carbon Equivalent — Pcm (Ito-Bessyo)

Better for low-carbon microalloyed steels (C < 0.18%):

Weldability Classification

CE Range	Weldability	Preheat
< 0.35	Good	None / optional
0.35 – 0.40	Good–Fair	50–100 °C for t > 25 mm
0.40 – 0.45	Fair	100–150 °C
0.45 – 0.50	Fair–Poor	150–200 °C
0.50 – 0.60	Poor	200–250 °C
> 0.60	Very Poor	250–300 °C, special procedures

Practical Example

Example — S355J2 (1.0577)

Typical composition: C=0.18, Mn=1.50, Cr=0, Mo=0, V=0.05, Ni=0, Cu=0

CE = 0.18 + 1.50/6 + (0+0+0.05)/5 + (0+0)/15 = 0.18 + 0.25 + 0.01 = 0.44

Weldability: Fair → Preheat 100–150 °C recommended for t > 20 mm

Steel Grade Equivalent & Carbon Equivalent Calculator

Published by Nikolai Shelkovenko on February 15, 2026 March 5, 2026

Results

Carbon Equivalent — IIW Formula

Carbon Equivalent — Pcm (Ito-Bessyo)

Weldability Classification

Practical Example