(4)variousmetallurgicalreacti***,suchasdeoxidation,sulfurremoval,phosphorusremovalandsoon,willbecarriedoutaftermelting,soastoimprovetheweldqualityandreducetheburninglossofalloyingelements;(5)addingtheneededalloyelementstotheweldmetalthroughthecoatingtoimproveandcontrolthechemicalcompositionoftheweldmetaltoobtainthedesiredproperties;(6)thecasingisformedintheprocessofwelding,thearcblowingforceisincreased,thearcheatisconcentrated,thedropletistransferredtothemoltenpool,andtheworkingprincipleoftheweldingprocessisaccomplished,thecurrentandvoltagearereducedbythethree-phasemaintransformer.TheoutputcurrentiscontrolledbychangingthephaseoftheSCRtriggerangle.Rectifierstraightening)