Kotel'chuk O. Development of flux-cored wire for welding of butt joints of low-alloyed steels in vertical plane with a forced formation of weld

A new self-shielding low-slag flux-cored wire has been developed for welding of butt joints of low-alloyed steels in vertical plane using forced formation of weld. Having applied the proposed experimental-computation method for prediction of the evolution degree of gas generation reactions during heating of the core of flux-cored wire with the rates corresponding to welding process, the composition of gas- and slag-generating part of the wire core was put forward. It was found that the increase in efficiency of gas shielding of molten metal during welding with low-slag generating self-shielding flux-cored wire can be achieved by use of the found combination of oxides, fluorides and mixtures of alkaline and alkali-earth metals. On the basis of numeric modeling of microstructure formation of one-pass weld metal and experimental investigation of the system "composition - microstructure - properties" the rational C-Mn-Si-Ni-Mo system and range of allowing were determined to provide the specified properties of the welds under conditions of thermal cycle of welding with forced-formation of the weld. The developed flux-cored wire has found its application in welding of bridge structures and reservoirs.