Welding Heat Input Calculator
kJ/mm — voltage × current ÷ travel speed
📚 Learn more — how it works, FAQ & guide Click to expand
Learn more — how it works, FAQ & guide
Click to expand
Welding Heat Input Calculator (kJ/mm)
Heat input = (Voltage × Current × η) ÷ Travel speed. Critical for welding procedure qualification (WPQ), distortion control, microstructure prediction. Per AWS D1.1.
How to use this tool
- 1
Process + voltage
SMAW / GMAW / GTAW / SAW.
- 2
Current + travel speed
Amps × travel mm/min.
- 3
See heat input
kJ/mm or kJ/in. Compare to spec.
Frequently Asked Questions
What is heat input used for?
Welding procedure qualification, microstructure prediction, distortion control. Too low: lack of fusion. Too high: HAZ damage, distortion, brittleness.
Process efficiency factors?
SMAW (stick): 0.75 · GMAW (MIG): 0.85 · FCAW: 0.85 · GTAW (TIG): 0.65 · SAW: 1.00. From AWS D1.1 standard.
Typical limits?
Carbon steel structural: 0.5-3.0 kJ/mm. Stainless 304: max 1.5-2.0 kJ/mm to avoid sensitization. Aluminum: limited by heat distortion.
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