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. This calculator assumes B = 0 (no boron input); for boron-treated steels add 5×B manually.

免費工程工具

鋼材等級對照與 CE 計算器

跨 EN、AISI、DIN、JIS 標準對照鋼材等級。計算碳當量 (CE)、可焊性及預熱溫度。

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

結果

碳當量 CE (IIW)

—

可焊性評估

—

預熱建議

—

Pcm (Ito-Bessyo)

—

等級對照

—

典型屈服強度 / 抗拉強度

—

EN	W.Nr.	AISI	DIN	JIS	類型	CE

碳當量 — IIW 公式

碳當量 — Pcm (Ito-Bessyo)

適用於低碳微合金鋼 (C < 0.18%)：

注意：此計算機無硼輸入項，並假設 B = 0 計算 Pcm（適用於無硼鋼）。對於含硼鋼，請將 5×B（質量 %）加至結果中。

可焊性分類

CE 範圍	可焊性	預熱
< 0.35	良好	無 / 選配
0.35 – 0.40	良好–尚可	t > 25 mm 時為 50–100 °C
0.40 – 0.45	尚可	100–150 °C
0.45 – 0.50	普通–不良	150–200 °C
0.50 – 0.60	差	200–250 °C
> 0.60	非常不良	250–300 °C，需特殊程序

實務範例

範例 — S355J2 (1.0577)

典型成分： 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

可焊性：尚可 → 建議 t > 20 mm 時預熱 100–150 °C