Submerged arc welding

Brief explanation on submerged arc welding

1. Shri S’ad Vidhya Mandal Institute Of Technology Presented by Singh Lav 150450119159 Singh Pranjul 150450119160 Sojitra Samarth 150450119161 Presentation on Submerged arc welding

2. Welding is a process of joining similar metals by application of heat with or without application of pressure and additional of filler material.

3. Submerged-Arc Welding

4. The fluxed used in the process include lime, silica, manganese oxide, calcium fluoride and other compounds free from gas producing substances. They available in many different grades. The filler wire used may be bare or slightly copper coated. The welding action is initiated by one of the many methods available depending upon the equipment used. In some cases the welding is started by striking an arc in the conventional way by letting the electrode touch the workpiece under the flux layer and slightly withdrawing it. In others, the welding action can be initiated by introducing a piece of high resistance conducting material like steel wool or carbon between the electrode and the workpiece . Once the welding action has been initiated the intense heat produced by the flow of current in the high resistance path melts a part of the flux around the electrode forming a conducting pool. The end of the electrode dipping in the fluid flux and the base metal melt under the liquid flux pool. The molten filler displaces the liquid flux and fuses with the molten base metal forming the weld.    

5. The molten flux coating over the molten metal pool forms a blanket that eliminates spatter losses and protects the welded joint from oxidation. As welding proceeds, the molten weld metal and the liquid flux cool and solidify under a layer of unused flux. The molten flux on solidification forms a brittle slag layer which can be easily removed. Unused granular flux material can be reclaimed and reused. The molten flux layer above the weld provides conditions most suitable for the use of large currents which make possible rapid generation of intense heat. The molten flux and the granulated flux covering provide excellent insulation concentrating the heat generated in a small region making possible thorough fusion of the base metal and the flux metal. The concentrated heat permits high welding speeds and deep penetration. The flux can also be used as a carrier of alloying elements to be introduced into the weld metal. The intense heat and deep penetration permit use of narrow grooves in the base metal for edge preparation requiring smaller quantities of filler metal.  

6. Thin plates can be easily welded in one pass without any edge preparation while only a slight bevelling is necessary in most other cases. The quality of welds produced in submerged arc welding is very high with good toughness, ductility and uniformity of properties. Submerged arc welding is most suitable for welding in the downhand or flat position although welds can be made on a straight slope. The high speed of welding with the associated large quantities of flux filler metal melted require the weld to be in a near horizontal position to avoid the flowing out of the liquid weld metal and the flux. Materials successfully welded by the process include low carbon steel, medium carbon steel, heat resistant steel, corrosion resistant steel. high strength steels and non ferrule metals like monel metal, nickel and others. Submerged arc welding can also be easily adaptable to semi-or fully mechanized operation.

7. Basic equipments and its function. Wire feeder:- It is used to drive the electrode to the work through the contact tube of a welding gun welding head. Welding power source : To supply electric current to electrode. An arrangement for holding the flux and feeding of the arc.

8. To get optimum results they are depends on certain parameters; Welding current Arc voltage Arc travel speed Electrode size Heat Input rate

9. Advantages High deposition rates No arc flash or glare Minimal smoke and fumes Flux and wire added separately - extra dimension of control Easily automated Joints can be prepared with narrow grooves Can be used to weld carbon steels, low alloy steels, stainless steels, chromium-molybdenum steels, nickel base alloys

10. Limitations Flux obstructs view of joint during welding Flux is subject to contamination Þ porosity Normally not suitable for thin material Restricted to the flat position for grooves - flat and horizontal for fillets Slag removal required Flux handling equipment

11. Application Automotive, Aviation, Ship Building and Nuclear power industry. Fabrication of Pipes, Pressure Vessels Boilers, Rail road, Railways coaches. In heavy fabrication industry. Rebuilding of worm out parts.

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