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What are the classification of welding welding?
May 27, 2016

What are the classification of welding?


According to the characteristics of the metal welding process with fusion welding, pressure welding and braze welding in three categories.


Fushion welding is the workpiece interface to be heated to molten state in welding process, and plus-pressure is not accomplished the method for welding.During melting welding, thermal source forms the molten bath with the rapid heat fused of two workpiece interfaces to be welded.The molten bath moves forward with thermal source, and the cooling back forms continuous weld and two workpiece are connected in one.


In the fushion welding process, if direct contact with the atmosphere and high temperature of the molten pool, atmospheric oxygen will be oxidized metal and alloy elements. Air nitrogen, water vapor and other into the molten pool, but also in the subsequent cooling process in the formation of pores in the weld, slag, cracks and other defects, the deterioration of the quality and performance of the weld.


In order to improve the welding quality, various kinds of protection methods have been studied. For example, gas shielded arc welding is to use argon, carbon dioxide and other gases isolated from the atmosphere to protect the welding arc and weld pool rate; and as the steel welding, join in the electrode on the oxygen affinity of titanium iron deoxidation, you can protect the electrode in the beneficial elements manganese, silicon from oxidation and into the pool and cooling after obtain high quality welds.


Pressure welding is under pressure, so that two of the workpiece in the solid state to achieve the combination of atoms, also known as the solid state welding. Pressure welding process is commonly used in resistance welding, when an electric current passes through two workpiece end connection, the registry for a high resistance and temperature rise, when heated to a plastic state, under the action of axial pressure connected into a whole. The common characteristic of all kinds of pressure welding methods of table type cold welding machine is that the pressure is applied in the welding process and not filled with the filling material. Most welding processes such as diffusion welding, high frequency welding, cold pressure welding are not melting process, so there is no useful like welding that burning loss of alloy elements, and the harmful elements penetrated weld, in order to simplify the welding process, but also improve the welding safety and health conditions. At the same time as the heating temperature is lower than welding, heating time is short, so the small heat affected zone. Many materials, which are difficult to be welded with fusion welding, can often be welded into a high quality joint with the same strength as the base material.


Braze welding is the use of lower melting point than the workpiece metal for brazing, will to the workpiece and a solder heating is higher than the melting point of the solder, below the melting point of the workpiece temperature, the use of solder wetting liquid workpiece, filling gap interface and with the workpiece to achieve interdiffusion of atoms, so as to realize the welding method.


Welding is formed by connecting the joints of the two joints called the weld seam. The two sides of the weld will be affected by the welding heat, and the structure and the performance change, this area is called the heat affected zone. Welding materials, welding materials, welding current, welding and heat affected zone in the weld and heat affected zone may produce overheating, embrittlement, hardening or softening phenomenon, but also to the performance of the welding parts decreased, the deterioration of the welding properties. The need to adjust the welding conditions, welding preheating before welding pieces of the interface, welding heat and post weld heat treatment can improve the welding quality of welding.