Heat Input Calculator
Calculate welding heat input using the AWS D1.1 formula.
Thermal Efficiency by Process
| Process | Efficiency | Notes |
|---|---|---|
| SAW | 0.90-0.99 | Highest efficiency |
| SMAW | 0.70-0.85 | Common stick welding |
| GMAW/FCAW | 0.75-0.90 | MIG and flux-cored |
| GTAW | 0.50-0.80 | TIG welding |
| PAW | 0.60-0.80 | Plasma arc |
Understanding Heat Input
AWS D1.1 Heat Input Formula
Heat Input (J/mm) = (Voltage x Amperage x 60) / (Travel Speed in mm/min) x Efficiency
Why Heat Input Matters
- Metallurgy: Controls grain size, HAZ width, and mechanical properties
- Distortion: Higher heat input = more distortion potential
- Cracking: Some materials require heat input limits to prevent cracking
- Code Compliance: Many codes specify max heat input for qualified procedures
Typical Heat Input Ranges
- Low Heat Input: < 1.0 kJ/mm - For thin materials, low-alloy steels
- Medium Heat Input: 1.0 - 2.5 kJ/mm - General fabrication
- High Heat Input: > 2.5 kJ/mm - Heavy sections, SAW