The hysteresis reason of the critical current when welding on direct polarity with the coated wire from the easily ionized substances.

When welding on small currents on direct polarity in carbon dioxide the Св-08Г2С the wire with coverings from the Cs and K or Cs and Na salts taken in a certain ratio observes the globular metal transfer. At gradual increase in wire speed Vw, the welding current increases also at its certain value equal critical, the globular metal transfer in steps passes into jet at the welding current equal to Ikp1 and the wire feed of Vw1.

If on the same wire to make welding on the droplet transfer in the beginning and to gradually reduce current, then spasmodic transition from the droplet transfer to the globular metal transfer takes place at Ikp2 and Vw2 which size is there been less by Ikp1 and V1. At the same time the difference between the sizes Ikp1 and Ikp2 makes 20 … 30 A. Such phenomenon when welding in argon or helium wasn’t noted by usual wires in welding literature. Therefore, this phenomenon is caused by existence on the wire surface the salts of the easily ionized substances.

The salts of the easily ionized substances decomposition temperature is lower than the melting temperature significantly steel wires used in welding in carbon dioxide. The salt decomposition temperatures КNO3, NaNO3 and Cs2CO3 are respectively ~ 680 К, ~ 650 К and ~ 880 К.

Therefore, these salts decay and evaporate from the wire surface when welding without approaching border of its melting and in the form of the cloudlet are near border of the wire melting.

When welding on small currents, there is less critical, globular transfer is observed. In this case, the large drop together with the arch burning under a drop chaotically moves in space. It complicates access to the arch of the salts which have evaporated from a surface of the wire and demands their bigger quantity from the drop, i.e. the larger speed the wire feed  Vp (larger current) for transition from the globular transfer to the droplet gradual increase in welding current (increase in Vw).

The transition from the globular transfer to droplet transfer when welding by the coated wire with EIS comes from the certain size of force caused by excess charges in a cathode spot. The size of this force at the set EIS depends on amount of the EIS atoms getting to the arch. Therefore, the transition from the globular transfer to the droplet, as well as transition from the droplet transfer to the globular, happens at the same size of this force, so, at the same amount of the EIS atoms getting to the arch in unit of time.

When welding at high currents, high critical current, i.e. on spray metal transfer the  approach of the evaporated salts from the wire surface to the arch is complicated by nothing and it is better than a condition of their hit in the arch, than when welding on globular metal transfer. Therefore, at reduction of welding current (reduction of Vw) the same amount of EIS atoms will get to the arch at smaller Vw, so, and smaller current, than when welding on the globular transfer. Therefore, transition to the globular in this case has to come from droplet transfer at the smaller size Vw and smaller size of current, i.e. Ikr2 has to be less Ikr1, and Vw2 is less than Vw1, as is observed experimentally.

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