Carbon Equivalent Calculator

Formula Type:

Carbon (\( C \)) (%):

Manganese (\( Mn \)) (%):

Silicon (\( Si \)) (%):

Copper (\( Cu \)) (%):

Nickel (\( Ni \)) (%):

Chromium (\( Cr \)) (%):

Molybdenum (\( Mo \)) (%):

Vanadium (\( V \)) (%):

1. What is Carbon Equivalent Calculator?

Definition: This calculator determines the carbon equivalent (CE) or critical metal parameter (Pcm) of steel based on the weight percentages of alloying elements, aiding in assessing the steel's weldability.

Purpose: It is used in metallurgy and welding to predict the likelihood of hydrogen-induced cold cracking, helping engineers and welders decide on preheating requirements and welding techniques.

2. How Does the Calculator Work?

The calculator uses the following equations:

\( \text{CE (IIW)} = C + \frac{Mn}{6} + \frac{Cu + Ni}{15} + \frac{Cr + Mo + V}{5} \)
\( \text{CE (AWS)} = C + \frac{Mn + Si}{6} + \frac{Cr + Mo + V}{5} + \frac{Cu + Ni}{15} \)
\( \text{Pcm (JWES)} = C + \frac{Si}{30} + \frac{Mn + Cu + Cr}{20} + \frac{Ni}{60} + \frac{Mo}{15} + \frac{V}{10} + 5B \)
\( \text{CE (JWES)} = C + \frac{Si}{24} + \frac{Mn}{6} + \frac{Ni}{40} + \frac{Cr}{5} + \frac{Mo}{4} + \frac{V}{14} \)

Where:

\( C \): Carbon percentage (%);
\( Mn \): Manganese percentage (%);
\( Si \): Silicon percentage (%);
\( Cu \): Copper percentage (%);
\( Ni \): Nickel percentage (%);
\( Cr \): Chromium percentage (%);
\( Mo \): Molybdenum percentage (%);
\( V \): Vanadium percentage (%);
\( B \): Boron percentage (%).

Steps:

Select the formula type (IIW, AWS, JWES Pcm, or JWES CE).
Enter the weight percentages of alloying elements (\( C \), \( Mn \), \( Si \), \( Cu \), \( Ni \), \( Cr \), \( Mo \), \( V \)).
If JWES Pcm is selected, enter the Boron percentage (\( B \)).
Validate inputs: Ensure \( C \leq 2.14\% \) and all percentages are non-negative.
Calculate CE or Pcm using the selected formula.
Assess weldability:
- For CE formulas (IIW, AWS, JWES CE):
  - CE ≤ 0.40%: Very Good (No preheating).
  - 0.40% < CE ≤ 0.60%: Moderate (Preheating may be required).
  - CE > 0.60%: Poor (Preheating compulsory).
- For Pcm (JWES Pcm):
  - Pcm ≤ 0.30%: Very Good (No preheating).
  - 0.30% < Pcm ≤ 0.50%: Moderate (Preheating may be required).
  - Pcm > 0.50%: Poor (Preheating compulsory).
Display results: CE or Pcm value and weldability assessment.

3. Importance of Carbon Equivalent Calculation

Calculating carbon equivalent or Pcm is crucial for:

Weldability Prediction: Determines the risk of cold cracking, guiding welding procedures.
Material Selection: Helps choose steels with suitable properties for specific applications.
Cost Efficiency: Avoids unnecessary preheating or overly conservative welding practices.

4. Using the Calculator

Example 1 (JWES Pcm Formula): Calculate Pcm for a steel alloy:

Composition: \( C = 0.18\% \), \( Si = 0.30\% \), \( Mn = 1.0\% \), \( Cu = 0.02\% \), \( Ni = 0.01\% \), \( Cr = 0.05\% \), \( Mo = 0.01\% \), \( V = 0.01\% \), \( B = 0.0005\% \);
Formula: \( \text{Pcm} = C + \frac{Si}{30} + \frac{Mn + Cu + Cr}{20} + \frac{Ni}{60} + \frac{Mo}{15} + \frac{V}{10} + 5B \);
Calculation: \( \text{Pcm} = 0.18 + \frac{0.30}{30} + \frac{1.0 + 0.02 + 0.05}{20} + \frac{0.01}{60} + \frac{0.01}{15} + \frac{0.01}{10} + 5 \times 0.0005 \);
\( \text{Pcm} = 0.18 + 0.01 + \frac{1.07}{20} + \frac{0.01}{60} + \frac{0.01}{15} + \frac{0.01}{10} + 0.0025 \);
\( \text{Pcm} = 0.18 + 0.01 + 0.0535 + 0.0001667 + 0.0006667 + 0.001 + 0.0025 \approx 0.2478 \);
Weldability: Pcm ≈ 0.2478% (Very Good, no preheating required);
Result: Pcm = 0.2478%, Weldability: Very Good.

Example 2 (JWES CE Formula): Calculate CE for AISI 1018 steel:

Composition: \( C = 0.20\% \), \( Si = 0.25\% \), \( Mn = 0.90\% \), \( Ni = 0\% \), \( Cr = 0\% \), \( Mo = 0\% \), \( V = 0\% \);
Formula: \( \text{CE} = C + \frac{Si}{24} + \frac{Mn}{6} + \frac{Ni}{40} + \frac{Cr}{5} + \frac{Mo}{4} + \frac{V}{14} \);
Calculation: \( \text{CE} = 0.20 + \frac{0.25}{24} + \frac{0.90}{6} + \frac{0}{40} + \frac{0}{5} + \frac{0}{4} + \frac{0}{14} \);
\( \text{CE} = 0.20 + 0.0104167 + 0.15 + 0 \approx 0.3604 \);
Weldability: CE ≈ 0.3604% (Very Good, no preheating required);
Result: CE = 0.3604%, Weldability: Very Good.

5. Frequently Asked Questions (FAQ)

Q: What is the difference between Pcm and CE formulas?
A: Pcm (JWES) focuses on critical metal parameters for high-strength steels, including Boron, with lower thresholds for weldability. CE formulas (IIW, AWS, JWES CE) are more general and assess overall hardenability.

Q: Why are Boron percentages typically very small?
A: Boron is a potent hardenability agent; even small amounts (e.g., 0.0005%) significantly affect steel properties, which is why the Pcm formula multiplies it by 5.

Q: Can this calculator be used for all steel types?
A: It is designed for carbon and low-alloy steels. High-alloy or stainless steels may require different formulas not covered here.