Author(s): B M PATCHETT
The effect of simple fluxes on heat transfer and arc stabil- ity has been investigated for both nonconsumable and consumable electrode arc processes using mild steel plate material. One and two component fluxes were made by sin- tering chemicals in the solid state to avoid composition alterations due to agglomeration or fusion. Weld bead penetration and surface condition were used as the criteria to assess heat transfer and arc stability characteristics, and the performance of each flux was judged by com- parison with a weld pass made with argon gas shielding. Chemical compounds used in flux formulations have individual effects on heat transfer and heat balance which depend on electrode polarity and electrode emission character- istics. Arc instability is also greatly affected by flux composition, and in extreme cases can lead to individual "spots" of molten metal rather than a weld bead. The time spent on one weld area is therefore variable, and affects penetration consistency and possibly ripple formation and weld bead uniformity. There are indica- tions that these effects are linked with the nature of electron emission of coated substrates, and with the effect of ion additions from fluxes to the anode and cathode fall areas, but the pattern is only consistent over a narrow range of simple materials.