1》 argon tungsten arc welding:

① Argon can effectively isolate air, is insoluble in metal and does not react with metal. During welding, the arc can also automatically remove the oxide film on the surface of the molten pool. Therefore, it can successfully weld non-ferrous metals, stainless steel and various alloys that are easy to oxidize, nitride and chemically active.

② Tungsten electrode arc is stable, and dozens of it can still burn stably under a small welding current (less than 10a), which is especially suitable for the welding of thin plates and ultra-thin materials.

③ The heat source and filler wire can be controlled separately, so the heat input is easy to adjust, and welding at various positions can be carried out. It is also an ideal method to realize single-sided welding and double-sided forming.

④ Since the droplet of filler wire does not pass through the arc, no spatter will occur, and the weld formation is beautiful.

2》 MIG welding:

① Inert gases have little chemical interaction with any metal.

② There is no coating layer on the surface of the welding wire, and the welding current can be increased. Therefore, the penetration of the base metal is large, the welding wire melting speed is fast, and the deposition rate is high. Compared with TIG (tungsten insert gas arc welding) welding, its production efficiency is high.

③ Droplet transfer mainly adopts jet transfer. Short circuit transition is only used in thin plate welding, while drop transition is rarely used in production. When welding aluminum, magnesium and their alloys, sub jet transition is usually used. Because the cathode atomization area is large, the molten pool protection effect is good, and the weld formation is good with few defects.

④ If short-circuit transition or pulse welding method is adopted, all position welding can be carried out, but its welding efficiency is lower than that of flat welding and horizontal welding.

⑤ Generally, DC reverse connection is adopted, so that the arc is stable, the droplet transfer is uniform, the splash is less, and the weld formation is good.

3》 CO2 welding:

① CO2 arc has strong penetration, which can increase the blunt edge of the groove and reduce the groove during thick plate welding; High welding current density and high welding wire melting rate; Generally, slag cleaning is not required after welding, so the productivity of CO2 welding is about 1 ~ 3 times higher than that of electrode arc welding.

② Pure CO2 welding can not achieve jet transfer within the general process range. It is commonly used: short-circuit transfer and drop transfer. Jet transfer can be obtained only after mixed gas is added.

③ Short circuit transfer can be used for all position welding, and the welding quality of thin-walled components is high and the welding deformation is small.

④ It has strong rust resistance, low hydrogen content in weld, and little tendency to cold crack when welding low alloy high strength steel.

⑤ CO2 gas is cheap, and the cleaning of weldments before welding can be simplified. Its welding cost is only 40% ~ 50% of that of submerged arc welding and electrode arc welding.

4》 submerged arc welding:

① High welding productivity

② Good weld quality

③ Low welding cost

④ Good working conditions

⑤ Wide welding range

5》 resistance welding: 

① the two metals are heated internally under pressure to complete the welding. Whether it is the formation process of the welding joint or the formation process of the joint surface, its metallurgical problems are very simple.

② Due to heat concentration and short heating time, the heat affected zone is small, and the deformation and stress are small. Generally, it is not necessary to consider the correction or heat treatment process after welding.

③ Simple operation, easy to realize mechanized and automated production, no noise and smoke, good working conditions.

④ With high productivity, it can be incorporated into the assembly line together with other manufacturing processes in mass production.

6》 manual electrode arc welding:

① The equipment used is relatively simple, relatively cheap and portable.

② Gas protection is not required.

③ Flexible operation and strong adaptability.

④ It has a wide range of applications and is suitable for the welding of most industrial metals and alloys