Welding, also known as welding, is a manufacturing process and technology for joining metals or other thermoplastic materials such as plastics by heating, high temperature, or high pressure.
There are many energy sources for modern welding, including gas flames, electric arcs, lasers, electron beams, friction and ultrasonic waves. In addition to being used in factories, welding can also be carried out in a variety of environments, such as the field, underwater and space. No matter where it is, welding may bring danger to the operator, so appropriate protective measures must be taken when welding. The possible harm to the human body caused by welding includes burns, electric shock, visual impairment, inhalation of toxic gases, excessive ultraviolet radiation, etc.
Welding achieves the purpose of joining through the following three ways:
Fusion welding-heating the workpiece to be joined to partially melt it to form a molten pool. The molten pool will be joined after cooling and solidification. If necessary, a filler can be added to assist. It is suitable for welding of various metals and alloys. pressure.
2. Pressure welding-the welding process must apply pressure to the weldment, which belongs to the processing of various metal materials and some metal materials.
3. Brazing-use a metal material with a lower melting point than the base material as the brazing filler metal, use the liquid brazing filler metal to wet the base metal, fill the joint gap, and mutually diffuse with the base metal to realize the connection of the weldment. It is suitable for welding processing of various materials, and also suitable for welding processing of different metals or dissimilar materials.
Penetration type (small hole type) plasma arc welding: using the characteristics of small plasma arc diameter, high temperature, high energy density, and strong penetrating power, under appropriate process parameters (larger welding current 100A～500A) It is a plasma arc welding method in which the weldment is completely penetrated, and under the action of the plasma flow, a small hole is formed through the weldment, and part of the plasma arc is sprayed from the back of the weldment. It can be welded on one side and on both sides. It is most suitable for welding 3-8mm stainless steel, 12mm titanium alloys, 2-6mm low carbon steel or low alloy structural steel, and butt welding of copper, brass, nickel and nickel alloys. (The plate is too thick, limited by the energy density of the plasma arc, it is difficult to form small holes; the plate is too thin, the small holes cannot be completely closed by liquid metal, and the small hole welding method cannot be realized.)
Penetration type (melting type) plasma arc welding: using a smaller welding current (30A ~ 100A) and a lower plasma gas flow, using a hybrid plasma arc welding method. No pinhole effect is formed. Mainly used for the welding of thin plates (0.5～2.5mm or less), the welding of all layers after the bottom welding bead of multi-layer welding, and the welding of fillet welds.
Micro-beam plasma arc: plasma arc welding with welding current below 30A. The diameter of the nozzle is very small (Φ0.5～Φ1.5mm), and a needle-like fine plasma arc is obtained. Mainly used for welding ultra-thin, ultra-small and precise weldments below 1 mm.