1. Advantages and disadvantages of tungsten inert gas welding.
1. Advantages of tungsten inert gas welding
(1) Argon gas effectively isolates air and is insoluble in metal, does not react with metal, and during the welding process, the arc can automatically clean the oxide film on the surface of the molten pool. Therefore, it can successfully weld easily oxidized, nitrified and chemically active non-ferrous metals, stainless steel and various alloys.
(2) The tungsten electrode arc is stable and can still burn stably at very low welding currents (less than 10A), making it particularly suitable for welding thin sheets and ultra-thin materials.
(3) The heat source and filler wire can be controlled separately, so the heat input is easy to adjust and multi-position welding can be realized. It is also an ideal method to achieve one-sided welding and two-sided forming.
(4) Because the filler wire drops do not pass through the arc, there is no spatter and the welding seam is beautiful.
2. Disadvantages of tungsten inert gas welding
(1) The depth of the weld seam is shallow, the deposition rate is low, and the productivity is relatively low.
(2) The tungsten electrode has low current-carrying capacity. Excessive current can cause melting and evaporation of tungsten, and tungsten particles can enter the molten pool, causing contamination (tungsten inclusion).
(3) Inert gases (argon, nitrogen) are relatively expensive, and compared with other arc welding methods (such as manual arc welding, submerged arc welding, carbon dioxide gas shielded welding, etc.), the production cost is higher.
Note: Pulsed tungsten inert gas welding is suitable for thin plate welding, especially full position butt welding. Tungsten inert gas welding is generally only suitable for welding parts with a thickness of less than 6 mm.
2. Characteristics of argon arc welding with consumable electrode:
(1) Just like TIG welding, it can weld almost all metals, especially suitable for welding materials such as aluminum and aluminum alloys, copper and copper alloys, and stainless steel.
(2) Because the welding wire acts as an electrode, a high-density current can be used, so that the base metal has a large penetration depth and the filler metal has a fast deposition rate. When used to weld thick plates of aluminum, copper and other metals, the productivity is higher than that of TIG welding and the welding deformation is lower than that of TIG welding.
(3) Argon arc welding with consumable electrode can have DC reverse connection, which has a good sputtering effect when welding aluminum and its alloys.
(4) The inherent regulation effect of subsonic arc is more significant when welding aluminum and its alloys with argon arc welding with consumable electrode.
3. Advantages and disadvantages of MIG welding
MIG welding generally uses inert gas (argon, helium or their mixture) as a shielding gas in the welding zone.
1. Advantages of MIG welding
(1) Inert gas almost does not react with any metal and is insoluble in metal, so it can weld almost all metals.
(2) The welding wire has no coating layer, and the welding current can be increased, so the base metal has a large penetration depth, the welding wire has a fast melting speed, and the deposition rate is high. Compared with TIG (tungsten inert gas arc welding), its production efficiency is high.
(3) Jet transition is mainly used for droplet transition. The short circuit transition is only used in thin plate welding, while the droplet transition is rarely used in production. When welding aluminum, magnesium and their alloys, subsonic arc transition is generally used because the sputtering region is large, the shielding effect of the molten pool is good, and the weld seam is well formed with fewer defects.
(4) If the short-circuit transition method or pulse welding is used, full-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 used, so the arc is stable, the droplet transition is uniform, the spatter is small, and the weld seam is well formed.
2. Disadvantages of MIG welding
(1) Inert gas is expensive and the cost is high.
(2) It is sensitive to oil and rust on the base metal and welding wire and has a tendency to generate pores.
(3) Compared with CO 2, its penetration depth is shallower and its wind resistance is poor, so it is not suitable for outdoor welding.
4. Advantages and disadvantages of CO 2 Welding:
Advantages of CO 2 Welding
(1) The CO2 arc has strong penetration and can increase the blunt edge of the groove and reduce it when welding thick plates; the welding current density is large and the welding wire melting rate is high. Generally, there is no need to clean the slag after welding, so the productivity of CO2 welding is about 1-3 times that of electric arc welding.
(2) Pure CO 2 welding cannot achieve jet transition within the general process range. Short-circuit transition and droplet transition are commonly used. It is possible to obtain jet transition only after adding a gas mixture.
(3) Short-circuit transition can be used for full-position welding and has high welding quality for thin-walled components with small welding deformation. Because the arc heat is concentrated, the heated area is small, the welding speed is fast, and the CO2 airflow plays a certain cooling role in welding, which can avoid burning the welded parts and reduce the deformation of the welding part. welding.
(4) It has strong rust resistance, low hydrogen content in the weld seam, and less tendency to cold cracking when welding high-strength low-alloy steel.
(5) The price of CO2 gas is cheap, welding cleaning before welding can be simplified, and its welding cost is only 40%-50% of submerged arc welding and electric arc welding.
Disadvantages of CO 2 Welding
(1) During the welding process, there is more metal spatter, especially when the welding process parameters do not match properly, which may be more serious.
(2) The arc atmosphere has strong oxidizing properties and cannot weld easily oxidizable metal materials. Its wind resistance is poor and outdoor operations require wind protection measures.
(3) The welding arc is strong, especially when welding at high current, attention should be paid to protecting operators from arc radiation.
5. Advantages and disadvantages of submerged arc welding
Advantages of submerged arc welding
(1) High welding productivity
The. There is no limit to the decomposition of coating components, so much higher currents can be used compared to electric arc welding;
B. Due to the insulating effect of flux and slag, the speed of submerged arc welding is greatly improved.
(2) Good quality of welding seam
The. Protected by flux and slag;
B. Gas has reducing properties;
w. More time for metallurgical reactions reduces the possibility of defects such as porosity and cracks in the weld bead; d. Welding parameters can be kept stable through automatic adjustment.
(3) Lower welding cost
The. The large welding current used in submerged arc welding can cause the welding to have a greater depth of penetration;
B. Very few metallic splashes; w. The heat from submerged arc welding is concentrated, with high thermal efficiency.
(4) Good working conditions
The. Mechanization;
B. Better working conditions for welders.
(5) Wide range of welding applications.
Disadvantages of submerged arc welding
(1) Difficult to weld in spatial positions.
(2) High requirements for the assembly quality of welded parts.
(3) Not suitable for welding thin plates and short welds.
6. Advantages and disadvantages of resistance welding
Advantages of resistance welding
(1) The two metals are welded from the inside under pressure in resistance welding, and the metallurgical problems in the welding spot formation process or joint surface formation process are simple. Therefore, there is no need for flux or gas protection during welding, nor is it necessary to use filler metals such as welding wire or electrodes to obtain a good quality welded joint and low welding cost.
(2) Due to the concentrated heat and short heating time, the heat-affected zone is small, and the deformation and stress are also small. There is usually no need to consider correction or heat treatment after welding.
(3) Simple operation, easy to achieve mechanization and automated production, no noise or dust, and good working conditions.
(4) High productivity, can be combined with other manufacturing processes in large-scale production assembly production lines. Only butt-to-butt flash welding requires adequate insulation due to spark spatter.
Disadvantages of Resistance Welding
(1) Currently, there is a lack of reliable non-destructive testing methods, and welding quality can only be verified by process sampling and destructive testing, as well as various monitoring techniques to ensure it.
(2) Spot welding and seam welding require overlapping joints, which increases the weight of the components, and the tensile and fatigue strength of the joints is relatively low.
(3) The equipment has high power and a higher degree of mechanization and automation. Therefore, investment in equipment is large and maintenance is more difficult. High power welding machines have difficulty powering the mains load. If it is a single-phase AC welding machine, it will have an adverse effect on the normal operation of the electrical grid.
Note: Resistance welding is suitable for a wide variety of materials. It can weld not only low carbon steel but also various alloy steels as well as non-ferrous metals such as aluminum, copper and their alloys.
7. Advantages and disadvantages of manual shielded metal arc welding
Advantages of manual shielded metal arc welding
(1) Relatively simple equipment is used for manual shielded metal arc welding, which is relatively cheap and light. AC and DC welding machines used in shielded metal arc welding are relatively simple, and no complex auxiliary equipment is required during welding operations, only simple tools are required. Therefore, the investment in equipment for purchasing welding rods is small and maintenance is easy, which is one of the reasons for its wide application.
(2) No gas protection is required. The welding rod not only supplies filler metal, but also produces gas to protect the weld pool and prevent oxidation during the welding process, and has strong wind resistance.
(3) Flexible operation and strong adaptability. Shielded metal arc welding is suitable for welding single parts or small batches of products, short or irregular welds, spatial positions and other welds that are not easy to achieve mechanized welding. Welding can be carried out wherever the welding rod reaches.
(4) Wide range of applications, suitable for welding most industrial metals and alloys. Appropriate welding rods can not only weld carbon steel and low-alloy steel, but also high-alloy steel and non-ferrous metals. It can not only weld the same metal but also different metals, as well as repair cast iron and various metal materials such as coatings.
Disadvantages of manual shielded metal arc welding
(1) High welding operator skill requirements and high training costs. The quality of shielded metal arc welding mainly depends on the skills and operational experience of the welding operator, as well as the use of welding rods, welding process parameters and appropriate welding equipment. Therefore, regular training of welding operators is necessary, which entails significant training costs.
(2) Poor working conditions. Shielded metal arc welding mainly relies on manual operation and visual observation, which can lead to high labor intensity for welding operators. Furthermore, the welding process involves high-temperature cooking and toxic fumes, leading to poor working conditions that require stricter labor protection measures.
(3) Low production efficiency. Shielded metal arc welding mainly relies on manual operation, and welding rods need to be replaced frequently during welding. Furthermore, slag cleaning needs to be carried out regularly, resulting in a lower welding production rate than automatic welding processes.
(4) Suitable for special metals and thin plates. For highly reactive metals (such as Ti, Nb, Zr, etc.) and refractory metals (such as Ta, Mo, etc.), the protection of welding electrodes is not sufficient to prevent oxidation of these metals, which may result in poor welding quality. Furthermore, low melting point metals such as Pb, Sn, Zn and their alloys are not suitable for shielded metal arc welding due to the high arc temperature. In addition, the thickness of the welded part for shielded metal arc welding is generally more than 1.5mm and is not suitable for welding thin plates below 1mm using this method.
