Welding Heat Input
Arc heat input Q = V·I·60 / (v·1000) - a key control parameter for thick-plate steel welding and hardness prevention.
Heat input
0.986kJ/mm
Formula, assumptions, and limits
$$Q = \eta \cdot \frac{V \cdot I \cdot 60}{v \cdot 1000}$$
Typical shipyard range 1–3 kJ/mm for 20–50 mm plate. Too low → fast cooling → hard HAZ and cracking; too high → coarse grain → low toughness. IACS UR W11/W22 require a Welding Procedure Qualification Record at specified heat input.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $V$ | Arc voltage | V | meter |
| $I$ | Welding current | A | meter |
| $v$ | Travel speed | mm/min | WPS |
| $η$ | Arc-process efficiency | - | AWS D1.1 / ISO 15614 |
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