Electroslag welding is widely used for metal compounds increased thicknesses of steel and iron of different composition, copper, aluminum, titanium and their alloys. The advantages of method is the possibility of a single pass welding of virtually any thickness of metal that does not require the removal of slag and appropriate adjustment of welding installation before welding the subsequent passage, as in other methods of welding. At the same time carry out welding without bevelling on the edges. For welding can use one or more wire electrodes or other electrodes enlarged cross-section. As a result, achieved high productivity and efficiency of the process increases with the thickness of the base metal.
Disadvantages include ways that the electro-slag welding is technically possible with the metal thickness exceeding 16 mm and with rare exceptions, is economically beneficial when welding metal thickness exceeding 40 mm. The method allows only vertical weld seams. When welding of certain metals in the formation of the weld metal and heat affected zone of unfavorable structures requires subsequent heat treatment to obtain the required properties of welded joints.
Electroslag Welding Technology. It is known that molten fluxes form slag, which are conductors of electricity. At the same time in the volume of the molten slag in the flow of the heat of the welding current is allocated. This principle underlies the electroslag welding. Electrode and the base metal is electrically connected through the molten slag (slag bath). Released in the heat of the slag bath overheats it above the melting temperature of the ground and the electrode metal. Used by the metal electrode and the edge of the base metal and fused because of the greater density of the metal than the slag flow down to the bottom of the melt, forming a molten metal bath. electrode metal in the form of individual droplets passing through the liquid slag, interacts with it, thus changing its composition. Slag bath, while the surface of molten metal, preventing its interaction with the air. When properly selected feed rate of the electrode gap between the end of the electrode and the surface of the metal bath is kept constant. welded metal, slag and metal bath kept from flowing normally forming a special device - mobile or fixed copper sliders 5, 6 water-cooled, and the remaining plates. The upper edge of the slide is slightly above the slag bath mirrors. Crystallizing in the bottom of the metal forms a molten metal bath seam 7. Slag bath, while the surface of the metal bath, cooled by contact with the sliders, which forms a thin crust of slag, thereby eliminating direct contact with the surface of the molten metal cooled slide and preventing the formation of the weld metal solidification cracking. consumption flux by this method of welding is small and usually does not exceed 5% by weight of weld metal. Due to the small amount of slag deposited metal doping is mainly due to the electrode wire. The share of the base metal in the weld can be reduced to 10-20%. The vertical position of the metal bath, fever, and the upper part of the large residence time of metal in the molten state, contribute to improving the conditions of removal of gases and nonmetallic inclusions in the weld metal. Compared with arc welding slag bath - less concentrated heat source. Therefore, the thermal cycle of electroslag welding is characterized by slow heating and cooling of the base metal. The deviation of the axis of the welded seam of the vertical may not be more than 15 ° in the plane of a sheet of bone and 30-45 ° from the horizontal. Since the release of heat in the slag bath is I mainly in the area of the electrode, the maximum thickness of the base metal, weld using a single electrode wire is usually limited to 60 mm. When welding thicker metal electrode in the gap between the edges of the com-schayut reciprocating (up to 150 mm) or use multiple fixed or movable electrodes. In this case, it is possible to weld metal of arbitrarily large thickness.
Electroslag Welding Technology
Electroslag Welding
Electroslag Welding Technique
No comments:
Post a Comment