Write the standard heat‑input formula used for GMAW and explain what higher heat input does to the weld.

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Multiple Choice

Write the standard heat‑input formula used for GMAW and explain what higher heat input does to the weld.

Heat input in GMAW is the energy delivered to the weld per unit length, controlled by voltage, amperage, and how fast you move the torch. The standard formula to quantify it is HI = (Volts × Amps × 60) / (Travel speed in mm/min × 1000) in kJ/mm. Here Volts × Amps gives power (watts); multiplying by 60 converts to joules per minute; dividing by travel speed (mm/min) yields energy per millimeter, and the 1000 converts joules to kilojoules per millimeter. Higher heat input means more energy per unit length, which generally increases penetration and bead size and enlarges the heat-affected zone. The weld cools more slowly, which can cause distortion and residual stresses, and it can raise the risk of hydrogen cracking if the weld environment has moisture or inadequate preheating. Controlling heat input helps achieve the desired bead geometry and mechanical properties. The form that omits the speed division or multiplies by speed would not correctly represent energy per length.

Heat input in GMAW is the energy delivered to the weld per unit length, controlled by voltage, amperage, and how fast you move the torch. The standard formula to quantify it is HI = (Volts × Amps × 60) / (Travel speed in mm/min × 1000) in kJ/mm. Here Volts × Amps gives power (watts); multiplying by 60 converts to joules per minute; dividing by travel speed (mm/min) yields energy per millimeter, and the 1000 converts joules to kilojoules per millimeter.

Higher heat input means more energy per unit length, which generally increases penetration and bead size and enlarges the heat-affected zone. The weld cools more slowly, which can cause distortion and residual stresses, and it can raise the risk of hydrogen cracking if the weld environment has moisture or inadequate preheating. Controlling heat input helps achieve the desired bead geometry and mechanical properties. The form that omits the speed division or multiplies by speed would not correctly represent energy per length.

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