Welding is a kind of processing technology which combines the weldment by heating or pressurizing, or using both, using or not using filler materials.
Classification of welding
The method of heating the weldment joint to the melting state and then cooling and crystallizing it into a whole.
Method of applying pressure (heated or unheated) to a weldment to complete welding. (forging welding, resistance welding, friction welding and gas pressure welding, cold pressure welding, explosive welding, etc.)
The solder with melting point lower than the weldment (base metal) is heated together with the weldment to make the solder melt (the weldment does not melt), then the flow of solder is used to fill the reserved space of the joint, and the solder is diffused and dissolved with the solid base metal, and the welding is realized after cooling.
Advantages of welding
1.Welding can save metal materials. Compared with riveting, welding can save metal materials, thus reducing the weight of the structure. Compared with bonding, welding has higher strength, and the bearing capacity of the welded joint can reach the same level as the weldment material.
2.The welding process is relatively simple, high productivity welding does not need a series of processes such as making wood mold, sand mold, smelting and casting like casting, nor does it need to open holes, make rivets and heat like riveting, so the production cycle is shortened.
3.Good welding joint quality
The welded joint not only has high strength, but also other properties (physical properties, heat resistance, corrosion resistance and sealing) can match with the weldment material.
4.High utilization of welding
Welding can be changed from big to small, and different materials can be connected to form a whole bimetal structure; different kinds of blanks can also be connected to form a cast weld, cast forge weld composite structure, so as to give full play to the potential of materials, improve the utilization rate of equipment, and make large-scale products with smaller equipment.
Disadvantages of welding
(1) Due to the poor construction and management, it is easy to produce various welding defects.
(2) There are large residual deformation and stress in the welded components without heat treatment after welding.
(3) In the process of welding, a lot of light radiation, harmful gases and smoke are often produced, which is not conducive to the health of welders.
Saying the screen as an example.
The stainless steel screen is welded by several units. The overlapping interfaces are welded by argon arc welding, so that each unit is firmly connected together, and then polished, polished, brushed and plated. It becomes the finished stainless steel screen we usually see.
Most stainless steel screens are made of tube, plate and flat steel. The most welding technology is made of tube and flat steel. The amount of welding technology is less when plate is used as the screen with hollow effect. Spot welding and full welding are commonly used. Electric welding workload is relatively small, full welding workload is large and relative price is much more expensive.