Three Types of Metal Welding Methods

There are more than 40 kinds of metal welding methods of wire cage welding machine, which can be mainly divided into three categories: fusion welding, pressure welding and brazing.

Fusion welding is the method of heating the workpiece joints to the melting state with adding no pressure to complete the process of welding by wire cage welding machine. During welding, the heat source will be rapidly welded to the two workpiece interface to form molten pool. The molten pool moves forward with the heat source, forming a continuous welding after cooling and connecting the two workpieces into one.

During welding, if the atmosphere is in direct contact with a high temperature pool, the oxygen in the atmosphere oxidizes metals and various alloying elements. Nitrogen and water vapor in the atmosphere enter the molten pool and form defects such as porosity, slag inclusion and cracks in the weld during subsequent cooling, which will deteriorate the quality and performance of the weld seam.

In order to improve welding quality, various protection methods have been developed. For example, gas shielded arc welding means to use argon, carbon dioxide and other gases to insulate the atmosphere to protect the welding arc and molten pool rate; and for example, when welding rebar, adding titanium iron powder with high oxygen affinity to the electrode coating for deoxidation, it can protect the beneficial elements such as manganese, silicon from oxidation and entering the molten pool, After cooling,  weld seam of high quality can be got.

Pressure welding is the combination of atoms between two workpieces in solid state under pressure, also known as solid state welding. Resistance butt welding by wire cage welding machine is commonly used in pressure welding. When the current passes through the joint of two workpieces, the temperature rises because of the large resistance. When heated to the plastic state, the connection becomes an integral whole under the action of axial pressure.

The common feature of all kinds of pressure welding methods is to apply pressure while welding without adding filler material. Most pressure welding methods, such as diffusion welding, high frequency welding, cold pressure welding and so on, all of them have no melting process, so there is no burning loss of beneficial alloy elements as in fusion welding and the problem of harmful elements invading the weld seam, thus simplifying the welding process and improving the welding safety and conditions. At the same time, because the heating temperature is lower than the fusion welding and the heating time is short, the heat affected zone is small. Many materials that are difficult to weld by melt welding can often be welded into joints of the same strength as the base metal by pressure welding.

Brazing is to use metal materials with lower melting point than the workpiece to be the solder, heating the workpiece and solder to a temperature higher than the melting point of the solder, lower than the melting point of the workpiece, wetting the workpiece with liquid solder, filling the gap between the interface and atoms with the workpiece to achieve mutual diffusion, so as to achieve welding method.