Welding & Joining
Welding Heat Input
Calculate heat input per unit length for arc welding processes (MIG, MAG, TIG, SMAW). Heat input affects microstructure, heat-affected zone (HAZ) size and mechanical properties.
Units:
Heat input controls HAZ size and cooling rate. Too high → coarse grain HAZ, reduced toughness. Too low → lack of fusion, rapid cooling, risk of hydrogen cracking. EN 1011 specifies max heat input per material/thickness.
Q [kJ/mm] = (U [V] × I [A] × 60) / (v [mm/min] × 1000) × k
Input
Arc voltage U iMeasured arc voltage in Volts. Typical: MIG/MAG 18–32V, TIG 10–20V, SMAW 22–28V.
V
Welding current I iWelding current in Ampères. Typical: MIG/MAG 100–350A, TIG 50–250A.
A
Travel speed v iWeld travel speed in mm/min. Typical: MIG/MAG 200–600, TIG 100–300 mm/min.
mm/min
Thermal efficiency k iProcess thermal efficiency factor k per EN 1011. MIG/MAG: 0.8, TIG: 0.6, SAW: 1.0, SMAW: 0.8.
Result
Heat input Q [kJ/mm]
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Heat input Q [kJ/m]
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Assessment
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