Active fluxes:
Active fluxes are those fluxes that add manganese and silicon to the weld deposit in proportion to the arc voltage. As voltage increases, the amount of flux consumed during the welding process also increases, which leads to more Mn and Si added to the weldment. The addition of Mn and Si make active fluxes well suited to welding over rust, mill scale and light oil. They also provide excellent welder appeal. However, due to the alloying tendency of active fluxes, they can add excessive amounts of Mn and Si, which can lead to weld embrittlement and/or cracking. As a result, active fluxes are recommended only for use below 36 volts and for single or multiple pass welds up to 1-inch thickness.
Advantages of Active Fluxes:
+ Good for use over rust, mill scale, even light rust
+ Excellent slag peeling characteristics
+ High speed capability
+ Improved weld metal wetting
