Weld Heat Input
Arc energy is what the power source delivers: U × I / travel speed. Heat input is the part of it that reaches the work, after the process's thermal efficiency k from EN 1011-1.
Heat input sets how fast the joint cools. Too little and the heat-affected zone hardens and can crack; too much and it loses toughness and distorts. That is why a procedure qualifies a window for it — and why it matters which of the two numbers the procedure wrote down.
Welding parameters
Travel speed
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Arc energy
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Thermal efficiency k
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Heat input
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Heat input
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Check against the WPS
Heat input per pass from nominal settings. Pulsed and waveform-controlled processes need instantaneous power rather than U × I, and a procedure qualification governs over any calculated value. A helper, not a substitute for engineering judgment or the governing code.