Arc welding with flux cored wire
Submerged arc welding, especially semi-automatic, is difficult because of the impossibility of precise direction of the electrode in a breaker and monitor formation of the joint. When welding in protective gases reliability of protection can be violated because of the drafts, splashing gas nozzles, etc. In these circumstances, the use of flux-cored wires, which combine the positive properties of open steel electrodes (protection, alloying and deoxidation of molten metal), and mechanized welding solid wire (high performance) is the big advantage of manufacturing, especially assembling conditions. This is facilitated by the absence of gas equipment (cylinders, hoses, gas motors), flux and flux instrumentation, complicating the process of welding or increase its complexity (filling and cleaning of flux, etc.).
Possibility of observing in the direction of semi-automatic welding electrode in a breaker, especially when welding, with its transverse vibrations, as well as the formation of the seam - the main pre-welding flux cored wire of the property. Changes in the composition of the core flux-cored wire filler can influence the chemical composition of the weld and the technological characteristics of the arc.
Summary of the method. Design powder wire defines certain features of its arc melting. The core wire for 50-70% consists of non-metallic materials, and therefore its electrical resistance is large - several hundred times larger than the metal shell. Therefore, almost all of the welding current is passed through a metal shell, melting it. The melting of the core is placed inside a metal shell is mainly due to teploizluche-of heat transfer from the arc and molten metal shell. Therefore, the core can protrude from the membrane, the bath of molten metal to touch or move it partially unmelted state. This increases the contamination of the weld metal by nonmetallic inclusions.
Welding technique. Usually cored wires used for welding hose semiautomatic. Due to the possibility of observing the formation of the seam welding technique butt and fillet welds in various compounds does not differ from that of their gas-shielded welding consumable electrode. However, the formation on the surface of molten pool of slag, fall asleep under certain conditions, the gap between the edges of the front of the weld pool, hinders root penetration weld. In multilayer welding surface of the previous layers should be thoroughly cleaned of slag. welding with flux cored wire has its drawbacks. Low stiffness of tubular cored wire feeders require the use of limited force of compression in the wire feed rollers. Release the wire in the main diameter of 2.6 mm or more, requiring the application of sustainable arc welding of high currents, making them suitable for welding only in the lower and rarely in an upright position. This is because the weld pool formed high-volume, covered with flowable slag is not kept in vertical and overhead positions of the force of surface tension and the pressure of the arc. presence on the surface of the molten pool of slag, slowing down the crystallization of the molten metal also affects the conditions of formation of the seam in the spatial positions, than the lower. A significant drawback of flux-cored wires, constraining their widespread commercial use - increased the probability of formation in the joints has caused the presence of voids in the wire. In addition, the core components nerasplavivshiesya, going into the molten pool, contribute to the appearance of gaseous products. Dissociation of marble, oxidation and reduction of carbon by heating and melting ferromanganese in combination with marble and other processes may also lead to the formation of a metal welding bath gas phase. As a result, there are seams and internal surface pores. Under these conditions, welding conditions (current, voltage, offset electrode) has a great influence on the possibility of a long seam. Increases the probability of formation of pores and the moisture that gets into the filler wire during storage, and in addition, grease and rust, traces of which are available on a metal tape. cored wire can be used for welding in carbon dioxide. The probability of formation of porosity in the joints, in this case is reduced. Depending on the composition of the filler for welding using DC straight or reverse polarity of the source with hard or characteristics of steep-falling.
See also:
Automatic Arc Welding
Automatic ADS
Machines with a Constant Feed Rate of Electrode
Flux Equipment
Settings for Automatic Arc Welding
Automatic Submerged Arc Welding Introduction
Fluxes for Automatic Arc Welding
Processed Fluxes
Ceramic Fused Fluxes
Semi-Automatic Arc Welding
Arc Welding with Flux Cored Wire
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