Connection methods include hot welding and cold welding. Hot welding is to melt the welding part into a molten pool by heating, and the molten pool will join after cooling and solidification. Specific methods include electric welding, gas welding, brazing, laser welding, electron beam welding, induction welding and friction welding. Cold welding is to combine atoms or molecules between parts by pressure or mechanical means, such as pressure welding and riveting welding. Each welding method is specified as follows:
Electric welding-heating the workpiece to be connected by electric arc to partially melt it to form a molten pool, then connecting it after cooling and solidification, and adding welding materials when heating, which is suitable for welding various metals and alloys. Electric welding can be subdivided into ordinary electric welding, argon arc welding, submerged arc welding and resistance welding.
Gas welding-combustion gas heats the joined workpiece to partially melt it to form a molten pool, and the molten pool cools and solidifies before joining. If necessary, fillers can be added to assist. It is suitable for welding all kinds of metals, alloys and nonmetals. Different flame temperatures are suitable for different welding. For example, a gas torch can weld plastic, while an oxyacetylene flame can weld steel.
Brazing-using metal materials with melting point lower than that of the base metal as brazing filler metal, wetting the base metal with liquid brazing filler metal, filling the joint gap, and diffusing with the base metal to realize connection welding. Suitable for welding of various materials and different metals or heterogeneous materials. Brazing is widely used in electronic industry.
Laser welding-heating the material to be welded by laser to partially melt it to form a molten pool, and then cooling and solidifying the molten pool to join. When necessary, filler can be added to assist, because the laser temperature is very high, which is suitable for welding between various metals, nonmetals and even different materials. For example, metals can be welded to ceramics.
Electron beam welding-heating the workpiece to be connected by electron beam to partially melt it to form a molten pool, and then connecting it after cooling and solidification, and adding filler for assistance if necessary. It is suitable for welding various metals and alloys.
Induction welding —— The workpieces to be connected are locally melted by induction heating to form a molten pool, which is connected after cooling and solidification, and fillers can be added for assistance if necessary. It is suitable for welding various metals and alloys.
Friction welding-heating the workpiece to be connected by friction, so that the contact part melts to form a molten pool, and then connecting after cooling and solidification. It is suitable for welding various metals and alloys.
Pressure welding-the welding process must exert pressure on the weldment, which belongs to the processing of various metal materials and some metal materials.
Riveting welding-the welded workpieces are connected by other materials, and like mechanical connection, various metallic materials and nonmetallic materials can be connected.
With the development of science and technology, more welding methods have been developed, such as plasma welding and micro-current welding.
Welding methods are widely used, but most of them may bring danger to operators, so appropriate protective measures must be taken during welding. Welding may cause harm to human body, including burns, electric shock, visual impairment, inhalation of toxic gases, excessive ultraviolet radiation, etc.