No abstract

Currently, there is a steady upward trend in the consumption of flux-cored wires in the global market of welding consumables. One of the rapidly developing technologies for the manufacture of metal structures is shielded gas arc welding with flux-cored wire with a metal core. According to the technology of use, metal cored wires do not differ from solid wires, and even surpass them in some technological characteristics. Taking into account global trends in the development of mechanized welding and the lack of domestic analogues, LLC TM.VELTEK has developed and mastered the manufacturing of high-performance metal cored wire TMB5-MK for welding in mixtures of 82% Ar + 18% CO2, 90% Ar + 10% CO2. The research aimed to study the features of the process of welding with metal cored wire compared to welding with solid wire. It has been established that metal cored wire provides high stability of arc burning in a wide range of welding modes. When welding at the same conditions in the optimal range, the index of stability of arc burning when using solid wire Sv-08G2S is 3 times lower. At the same time, the TMV5-MK wire provides a reduction in spatter losses, an increase in welding productivity and high mechanical properties of the weld metal. It is shown that the stability of the welding process is significantly affected by the electrodynamic properties of the power source and this factor must be taken into account when evaluating the welding and technological properties of welding wires and developing recommendations for their use.

The surfacing using flux-cored wire finds a wide application in many branches of industry and, first of all, in the repair works. At the present time the largest manufacturer of flux-cored wires for surfacing in Ukraine is the enterprise «TM. VELTEK». In the present work the developments of this enterprise and the experience of their use in repair surfacing of rolls of rolling stands, CCM rollers, wheel cranes and also the rollers of straightening machines and critical parts of hydraulic supports of mining equipment are described. 20 Ref., 3 Tables, 7 Figures. K e y w o r d s : arc surfacing, flux-cored wires, repair works, wear resistance, hardness, microstructure, increase in service llife Received 28.07.2016 Figure 7. Macrosection of plunger fragment after surfacing

Cored wires are used in numerous welding processes with or without external gas or flux shielding. Submerged arc welding (SAW) with cored wires, seamed or seamless, for joining mild and low alloyed steel grades is a technique that has demonstrated clear advantages during the three last decades. Ever since its invention, the SAW process has evolved with one main goal: to combine quality with productivity. With low alloy wires, the benefits have already been clearly demonstrated and widely exploited. However, little has been written on SAW and cladding with cored wires for corrosion or heat resisting applications. Its extension to high alloy compositions brings corresponding benefits and adds some specific and unique features. This paper focuses on consumable specificities and on the quality and productivity features of SAW with CRA (corrosion resistant alloy) cored wires. It describes the potential as well as the limitations of this technique. Cored wires are now used for submerged arc welding of almost all stainless steels ranging from soft martensitic to super-duplex, and for a series of nickel base compositions as well as for cladding cobalt base alloys. Examples of industrial applications with austenitic, duplex, martensitic and heat resisting stainless steels are given to illustrate the potential of the cored wire solution. 13 Ref., 4 Tables , 25 Figures.

Current aspects of the developing of modern self-shielding flux-cored wires composition for arc welding of low-alloyed steels are considered. Advantages and disadvantages of flux-cored wires of carbonate-fluorite, oxide and oxide-fluoride types of are shown in comparison. The effectiveness of gas shielding of molten metal at welding with self-shielding flux-cored wires of carbonate-fluorite type is analyzed considering the thermal properties of their cores. It is shown that to improve reliability of gas shielding at welding using the wires of this type it is important not only to ensure generation of sufficiently large volume of shielding gases at thermal destruction of the wire core, but also to control this process, providing gas evolution at all stages of heating and melting of the wire. The results of complex thermal analysis of the wire core mixtures containing, for example, lithium carbonate show substantially large heat losses for heating and melting of the wire core, which are accompanied by the development of energy-intensive processes of thermal destruction of core components. It is shown that the limitation of lithium carbonate content in the wire at the level of not more than 2 wt. % allows not only to preserve welding arc burning stability at the acceptable level but also to provide effective gas shielding of molten metal and easy separation of slag crust. The control of thermochemical reactions in the core is achieved by selection of its proper composition to ensure favorable melting of flux-cored wire and electrode metal transfer to the welding pool. Results of metallographic examinations of distribution and composition of non-metallic inclusions in metal of the welds made with wires of the oxide and oxide-fluoride types are presented. Main properties of the developed self-shielding flux-cored wires and recommendations on welding are given in conjunction with prospective fields of their application.