Laser Welding Heat Input Calculator
Calculate linear heat input (J/mm, kJ/cm), keyhole depth penetration, and thermal distortion parameters for handheld and automated fiber laser welders (1kW - 3kW).
Welding Setup Parameters
Low thermal conductivity traps heat locally. Prone to thermal buckling if heat input exceeds 90 J/mm on thin sheet.
HAZ Integrity: Optimal Narrow HAZ
High energy concentration minimizes heat affected zone width. Negligible thermal distortion and minimal post-weld straightening needed.
Thermal & Penetration Metrics
Heat Input Comparison (3mm Stainless)
Laser welding delivers 5x to 10x lower heat input than arc welding, virtually eliminating angular distortion and burn-through on sheet metal.
The Physics of Keyhole Laser Heat Input
1. Heat Input Formulation (ISO 1011-1)
The linear thermal energy transferred to the joint per unit length is defined as:
Where $P$ is laser power in Watts, $v$ is travel speed in mm/s, and $\eta$ is thermal efficiency. In fiber laser welding, multi-reflection within the vapor keyhole raises thermal coupling efficiency $\eta$ to 0.80 - 0.90, compared to only 0.25 for conduction-mode surface melting.
2. Cooling Rates & Microstructural Cracking
Because the surrounding cold metal acts as an immense heat sink, laser weld pools solidify rapidly (cooling times $t_1.6 < 1.5$ seconds). While this prevents sensitization in stainless steels, high-carbon steels ($C > 0.20\%$) may form brittle martensite without preheat.