Spray Arc Transition Current Intensity
The spray arc transition current is the point where the arc shifts from a short-circuit or globular arc to a fine-droplet spray arc during welding. This transition depends heavily on wire diameter and gas composition.
Physicochemical Mechanism of Action
The spray arc transition current is the current value at which the arc changes from an unsteady short-circuit or globular arc to a fine-droplet spray arc. This transition happens through changes in the gas composition and pressure that influence the arc type.
Metallurgical Relevance & Welding Risks
Too low a transition current can lead to irregular droplet formation and an unsteady arc, which causes poor welding results and a higher defect rate. Too high a current, on the other hand, can lead to excessive heat and a strong spray arc, which causes grain coarsening and reduced weld volume.
Workshop Practice & Instructions
The transition current should be set so the arc changes into a fine-droplet spray arc without being too high or too low. This can be done by adjusting the wire diameter and gas composition. For an all-round wire with a diameter of 1.6 mm and a gas composition of argon and carbon dioxide (75/25), the transition current typically lies between 300 and 400 amperes.