Arc energy and heat input

Formulas

E = U · I / v · 10⁻³  [kJ/mm], v in mm/s

Q = k · E

1 kJ/mm = 10 kJ/cm

Calculation rules

• Thermal efficiency factor k per ISO/TR 17671-1 (EN 1011-1): MMA (111) 0.8 · SAW (121) 1.0 · MIG/MAG (131, 135, 136, 138) 0.8 · TIG (141) 0.6.
• Speed: mm/min ÷ 60, m/min × 1000 ÷ 60 → mm/s. Changing the unit does not convert the entered number.
• Min–max range: minimum from I min, U min and v max; maximum from I max, U max and v min; mean = (min + max) / 2.
• ±25% band (× 0.75 / 1.25): heat input range of qualification per ISO 15614-1 (level 2 – upper limit where impact requirements apply, lower limit where hardness requirements apply).
• ±15% band (× 0.85 / 1.15): permitted deviation for aluminium alloys of group 23 per ISO/TR 15608 (precipitation-hardenable alloys) according to EN ISO 15614-2:2025.
• Tolerance check: deviation = (Q − Q₀) / Q₀ · 100%; ±15% and ±25% limits inclusive. Check detailed requirements in the standard for your material and in the WPQR.
• Rounding: kJ/mm – 3 decimal places, kJ/cm – 2 decimal places, deviation in % – 1 decimal place.