What kinds of welding are there?

Question 1: What are the current welding methods? There are many kinds of five-point welding methods, but according to their different technological characteristics, they can be divided into three categories: fusion welding, pressure welding and brazing. Fusion welding is to heat the joint of two weldments to a molten state, and then cool and solidify into a whole without pressure, thus completing the welding. Pressure welding means that in the process of welding, pressure must be applied to the welded parts while heating (or not heating) to complete the welding. Brazing is to melt the solder with low melting point and make it diffuse with the weldment metal (still heated, but still in solid state) to realize the connection.

Separate fusion welding, pressure welding and brazing. Fusion welding is divided into arc welding, electroslag welding, plasma arc welding and gas welding; Arc welding is divided into manual arc welding, automatic or semi-automatic submerged arc welding and gas shielded arc welding; Pressure welding is divided into forging welding, resistance welding, friction welding and cold pressure welding; Resistance welding is divided into butt welding, spot welding and seam welding; Brazing is divided into soldering iron brazing, flame brazing and salt bath brazing.

The answer has been supplemented and modified according to the question!

Question 2: What are the forms of welding? The above answer is only the welding method code, not the welding form, but actually the welding method.

Welding is the process of forming an integral joint through the connection between atoms and the diffusion between protons. It can also be considered that welding is a method to connect two or more workpieces together with filler materials by using thermal energy or mechanical pressure, or both, and become an inseparable and firm joint.

1, welding method

First, fusion welding

In the welding process, the weldment joint is heated to a molten state, and the welding is completed without pressure. Under the heating condition, the atomic kinetic energy of metal is enhanced, which promotes the mutual diffusion between atoms. When the welded metal is heated to a molten state to form a liquid molten pool, atoms can fully diffuse and closely contact, so after cooling and solidification, a solid welded joint is formed (ice can be used as an analogy). Common gas welding, arc welding, electroslag welding and gas shielded welding are all fusion welding methods.

Second, pressure welding.

This is a welding method in which pressure (heating or not) must be applied to the weldment to complete welding. There are two forms of this welding. One is to heat the contact part of the welded metal to a plastic state or a local melting state, and then apply a certain pressure to combine the metal atoms to form a firm welded joint, such as forging welding, contact welding, friction welding, gas pressure welding, etc. Secondly, under the condition of no heating, only enough pressure is applied to the contact surface of the welded metal to make the atoms approach each other by plastic deformation caused by pressure, and a firm joint can be obtained. This method includes cold pressure welding, explosive welding, etc. (mainly used for composite steel plates).

Third, brazing.

It is a method to connect weldments by using metal materials with melting point lower than that of base metal, heating weldments and solders to a temperature higher than that of solder but lower than that of base metal, wetting base metal with liquid solder, filling gaps between joints and diffusing with base metal. Common brazing methods are soldering iron and flame brazing.

2. Detailed description of welding method

First, fusion welding

1, gas welding:

Use oxyacetylene or other gas flame to heat the base metal and solder to achieve the purpose of welding. The flame temperature is about 3000℃. Suitable for thin workpieces, small diameter pipes, non-ferrous cast iron and brazing.

2, manual arc welding:

Manual welding method using arc as heat source to melt covered electrode and base metal to form weld. The arc temperature is about 6000-8000℃. Suitable for welding ferrous metals and some non-ferrous metals, with a wide range of applications, especially for short welds and irregular welds.

3, submerged arc welding:

The (automatic and semi-braking) arc burns under the flux zone, and the granular flux is used as the covering layer of the metal molten pool to isolate the air from entering the molten pool. The welding wire is continuously fed into the arc area by the wire feeder, and the welding direction and moving speed of the arc are completed manually or mechanically.

Suitable for welding straight and regular welds of carbon steel, low alloy steel, stainless steel and copper of medium and heavy plate.

4 gas welding:

(Gas shielded welding) Arc welding in which shielding gas is used to protect the welding area. Protective gas is used as a protective layer of metal bath to isolate air. The gases used are inert gas, reducing gas and oxidizing gas, which are suitable for welding carbon steel, alloy steel, copper, aluminum and other non-ferrous metals and their alloys. Oxidizing gas is suitable for carbon steel and alloy steel alloys.

5, ion arc welding:

The ultra-high temperature heat source generated by thermal contraction effect, mechanical contraction effect and magnetic contraction effect after gas ionization in arc is used for welding, and the temperature can reach about 20000℃.

Second, pressure welding.

1, friction welding:

Welded joints are formed by using the heat energy generated by mutual friction between welded parts and the rotation of contact end faces, and applying certain pressure. Suitable for welding aluminum, copper, steel and dissimilar metal materials.

2, resistance welding:

The weldment (or base metal) is heated to a plastic state or a partially melted state by using the resistance heat generated by current passing through the weldment, and then pressure is applied to connect the weldments together. Suitable for welding thin plates, pipes and bars.

Third, brazing.

1, soldering iron welding:

Use an electric soldering iron or flame to heat the heat of the soldering iron. Heat part of the base metal to melt the solder into the gap, so as to achieve the purpose of connection. Suitable for solder with melting point of 300℃. Generally used for welding wires, circuit boards and original parts.

2, flame brazing:

The gas flame is used as a heating source to heat the base material and melt the filled metal material into the gap to achieve the purpose of connection. Suitable for small-size weldments such as stainless steel, cemented carbide and non-ferrous metals.

3. Classification of welding methods

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Question 3: What are the types of electric welding and how to distinguish them? Take structural steel as an example: brand and compilation method. Knot XXX, structural steel covered electrode, No.3, represents coating type and welding current requirements, 1 No.2 and No.2 represent tensile strength of welding metal.

(2) covered electrode model

Covered electrode model is determined according to relevant national standards and international standards. EXXX, taking structural steel as an example, the model compilation method is that the letter "E" indicates covered electrode, the first and second digits indicate the minimum tensile strength of deposited metal, the third digit indicates the welding position of covered electrode, and the third and fourth digits indicate the welding current and coating type.

4. Classification of covered electrode

According to different situations, there are three kinds of classification methods for welding electrodes: classification according to the usage of covered electrode, classification according to the main chemical components of the coating, and classification according to the slag characteristics after the coating is melted.

According to the purpose of covered electrode, there are two expressions. One is compiled by the former Ministry of Machinery Industry. The welding covered electrode can be divided into: structural steel covered electrode, heat-resistant steel covered electrode, stainless steel covered electrode, surfacing covered electrode, low-temperature steel covered electrode, cast iron welding rod, nickel and nickel alloy covered electrode, copper and copper alloy electrodes, aluminum and aluminum alloy electrodes and special purpose electrodes. Second, according to national standards, it is carbon steel covered electrode, low alloy covered electrode, stainless steel covered electrode, surfacing covered electrode, cast iron welding rod, copper and copper alloy covered electrode, aluminum and aluminum alloy covered electrode. There is no principle difference between the two. The former is expressed by commercial brand, while the latter is expressed by mode.

According to the main chemical composition of covered electrode coating, covered electrode can be divided into: titanium oxide covered electrode, titanium oxide calcium covered electrode, ilmenite covered electrode, iron oxide covered electrode, cellulose covered electrode, low hydrogen covered electrode, graphite electrode and salt-based electrode.

According to the characteristics of molten slag of covered electrode coating, covered electrode can be divided into acidic covered electrode and alkaline covered electrode. The main components of acidic covered electrode coating are acidic oxides, such as silicon dioxide, titanium dioxide and iron oxide. The basic coating covered electrode coating is mainly composed of basic oxides, such as marble, fluorite and other flux-cored wires. The metal core in the coated covered electrode is called flux-cored wire. Cores are generally steel wires with a certain length and diameter. When welding, the welding core has two functions: one is to conduct welding current and generate electric arc to convert electric energy into heat energy, and the other is to melt the welding core itself as filler metal and fuse with liquid parent metal to form a weld.

In covered electrode welding process, the core metal accounts for a part of the whole weld metal. Therefore, the chemical composition of the core directly affects the quality of the weld. Therefore, the steel wire used as covered electrode core has its own brand and composition. If it is used as filler metal in submerged arc welding, electroslag welding, gas shielded welding, gas welding and other fusion welding methods, it is called welding wire. Effect of alloying elements in (1) core on welding

1) carbon (c) carbon is the main alloying element in steel. When the carbon content increases, the strength and hardness of steel increase obviously, while the plasticity decreases. In the welding process, carbon plays a certain deoxidation role, and combines with oxygen to generate carbon monoxide and carbon dioxide gas under the high temperature of the arc, which can eliminate the air around the arc zone and the molten pool, prevent the harmful gases of oxygen and nitrogen in the air from adversely affecting the molten pool, and reduce the contents of oxygen and nitrogen in the weld metal. If the carbon content is too high, the reduction will be severe, which will cause large splashes and pores. Considering the influence of carbon on the hardening ability and crack sensitivity of steel, the carbon content of low carbon steel core is generally 0. 1%.

2) Manganese (Mn) is a good alloying agent in steel, and its strength and toughness will increase with the increase of manganese content. In the welding process, manganese is also a good deoxidizer, which can reduce the oxygen content in the weld. Manganese and sulfide combine to form manganese sulfide floating in slag, thus reducing the tendency of weld hot cracking. Therefore, the manganese content of carbon structural steel core is 0. 30% ~ 0.55%, and the manganese content of some special steel wires is as high as 1.70%-2. 10%.

3) Si is also a good alloying agent. Adding proper amount of silicon to steel can improve the yield strength, elasticity and acid resistance of steel. If the content is too high, the plasticity and toughness will be reduced. In the welding process, silicon also has a good deoxidation ability, and forms silicon dioxide with oxygen, but it will increase the viscosity of slag and easily promote the formation of non-metallic inclusions.

4) Chromium (Cr) can improve the hardness, wear resistance and corrosion resistance of steel. For low carbon steel, chromium is an accidental impurity. The main metallurgical characteristic of chromium is that it is easy to be oxidized rapidly to form refractory oxide chromium trioxide (Cr203), which increases the possibility of weld metal inclusions. After chromium trioxide is transferred to slag, the viscosity of slag can be increased and the fluidity can be reduced.

5) Nickel (nickel-free has a significant effect on the toughness of steel, and generally requires a high low-temperature impact value ... >; & gt

Question 4: What kinds of electric welding can be divided into? The basic working principle of electric welding is that we reduce the voltage of the commonly used 220V voltage or 380V industrial power supply through the voltage reducer in the electric welding machine, enhance the current, and use the huge heat generated by electric energy to melt steel. The integration of coated covered electrode makes the fusion between steel higher. In addition, the coating on the outer layer of the electrode plays a very important role. Do you believe you can knock powder to see if you can weld it? Of course, this explanation is popular.

When welding an object, pay attention to that the included angle between the welding gun and the plane of the object to be welded is preferably 40-45 degrees. Of course, different thicknesses of objects require different currents and different covering electrodes!

I mainly want to explain the influence of electric welding on human body through the above principles: the factors harmful to human body in the process of electric welding will be different due to different types of electric welding, but in general, the following toxic and harmful substances will be produced: welding dust, carbon monoxide, manganese and its compounds, nitrogen oxides, ozone and ultraviolet rays.

1, welder's pneumoconiosis. Welding smoke can enter human body through respiratory tract, which mainly damages respiratory system. There are no clinical symptoms and signs in the early stage, and the onset length of service is generally more than 10 years.

2. Acute carbon monoxide poisoning. Carbon monoxide can enter the human body through the respiratory tract. It mainly damages the nervous system. It is characterized by severe headache, dizziness, palpitation, nausea, vomiting, weakness, rapid pulse, irritability, unsteady gait, unconsciousness, coma, convulsion, incontinence and shock. In severe cases, they will die immediately.

3. Chronic manganese poisoning. Can enter the human body through the respiratory tract. The onset of chronic manganese poisoning is generally slow, with neurosis and autonomic dysfunction in the early stage. After the disease continues to develop, there may be symptoms and signs of extrapyramidal nerve disorder.

4. Acute nitrogen oxide poisoning. Can enter the human body through the respiratory tract. It mainly damages the respiratory system. It is characterized by sore throat, chest tightness, cough and expectoration. There may be mild dizziness, headache, weakness, palpitation and nausea. , and then dyspnea, chest tightness, coughing up white or pink foam sputum, cyanosis of the mouth and lips, and even coma or suffocation.

5. Acute ozone poisoning. Can enter the human body through the respiratory tract. It mainly damages the respiratory system. Short-term low-concentration inhalation shows symptoms such as dry mouth and throat, sternal tightness, chest tightness, cough and expectoration, as well as drowsiness, headache, decreased analytical ability and abnormal taste. Inhalation of high concentration can gradually cause mucosal symptoms and pulmonary edema.

6. Occupational electro-optic ophthalmia and occupational electro-optic dermatitis. Long-term repeated ultraviolet irradiation can cause chronic blepharitis and keratitis; Exposure of the skin to intense ultraviolet radiation can cause dermatitis, manifested as erythema, sometimes accompanied by blisters and edema. After long-term exposure, the skin will shrink and age due to connective tissue damage and loss of elasticity, and more seriously, it will induce skin cancer.

Question 5: What are the welding types of steel bars? Single-sided lap welding, double-sided lap welding, groove welding, groove welding, resistance spot welding and flash butt welding. Welded steel bar. Keywords sleeve connection, cold lap joint,

Question 6: What are the forms of welding? The above answer is only the welding method code, not the welding form, but actually the welding method. Welding is the process of forming an integral joint through the connection between atoms and the diffusion between protons. It can also be considered that welding is a method to connect two or more workpieces together with filler materials by using thermal energy or mechanical pressure, or both, and become an inseparable and firm joint. 1, welding mode 1. Fusion welding is a method of heating welded joints to a molten state without pressure during welding. Under the heating condition, the atomic kinetic energy of metal is enhanced, which promotes the mutual diffusion between atoms. When the welded metal is heated to a molten state to form a liquid molten pool, atoms can fully diffuse and closely contact, so after cooling and solidification, a solid welded joint is formed (ice can be used as an analogy). Common gas welding, arc welding, electroslag welding and gas shielded welding are all fusion welding methods. Second, pressure welding is a welding method which can only be completed by applying pressure (heating or not) to the weldment during the welding process. There are two forms of this welding. One is to heat the contact part of the welded metal to a plastic state or a local melting state, and then apply a certain pressure to combine the metal atoms to form a firm welded joint, such as forging welding, contact welding, friction welding, gas pressure welding, etc. Secondly, under the condition of no heating, only enough pressure is applied to the contact surface of the welded metal to make the atoms approach each other by plastic deformation caused by pressure, and a firm joint can be obtained. This method includes cold pressure welding, explosive welding, etc. (mainly used for composite steel plates). 3. Brazing is a method of connecting weldments. By using a metal material with a melting point lower than that of the base metal, the weldments and solders are heated to a temperature higher than that of the solder and lower than that of the base metal, and the base metal is wetted with liquid solder to fill the gap between joints and diffused with the base metal. Common brazing methods are soldering iron and flame brazing. 2. Detailed description of welding method 1. Fusion welding 1. Gas welding: the parent metal and filler metal are heated by oxyacetylene or other gas flame to achieve the purpose of welding. The flame temperature is about 3000℃. Suitable for thin workpieces, small diameter pipes, non-ferrous cast iron and brazing. 2. Manual arc welding: A manual welding method that uses an electric arc as a heat source to melt covered electrode and form a weld with the base metal. The arc temperature is about 6000-8000℃. Suitable for welding ferrous metals and some non-ferrous metals, with a wide range of applications, especially for short welds and irregular welds. 3. Submerged arc welding: (automatic and semi-braking) the arc burns under the flux area, and the granular flux is used as the covering layer of the metal molten pool to isolate the air from entering the molten pool. The welding wire is continuously fed into the arc area by the wire feeder, and the welding direction and moving speed of the arc are completed manually or mechanically. Suitable for welding straight and regular welds of carbon steel, low alloy steel, stainless steel and copper of medium and heavy plate. Gas welding: (gas shielded welding) Arc welding using shielding gas to protect the welding area. Protective gas is used as a protective layer of metal bath to isolate air. The gases used are inert gas, reducing gas and oxidizing gas, which are suitable for welding carbon steel, alloy steel, copper, aluminum and other non-ferrous metals and their alloys. The oxidizing gas is suitable for the alloy of carbon steel and alloy steel. 5. Ion arc welding: after the gas is ionized in the arc, it is welded by the ultra-high temperature heat source generated by thermal contraction effect, mechanical contraction effect and magnetic contraction effect, and the temperature can reach about 20,000℃. 2. Pressure welding 1, friction welding: using the heat energy generated by mutual friction between weldments and rotation of contact end faces, a certain pressure is applied to form a welded joint. Suitable for welding aluminum, copper, steel and dissimilar metal materials. 2. Resistance welding: The weldment (or parent metal) is heated to a plastic state or a partially melted state by using the resistance heat generated by the current passing through the weldment, and then pressure is applied to connect the weldments together. Suitable for welding thin plates, pipes and bars. Third, brazing 1, soldering iron brazing: using electric soldering iron or flame to heat the heat of soldering iron. Heat part of the base metal to melt the solder into the gap, so as to achieve the purpose of connection. Suitable for solder with melting point of 300℃. Generally used for welding wires, circuit boards and original parts. 2. Flame brazing: gas flame is used as a heating source to heat the base metal, so that the solder melts into the gap to achieve the purpose of connection. Suitable for small-sized weldments, such as stainless steel, cemented carbide and non-ferrous metals. 3. Classification of welding methods

Question 7: There are several types of welding, including electric welding, gas welding, laser welding, brazing, hot melt welding, electron beam welding, explosive welding and so on.

2 welding: welding, which can also be written as "welding" or "welding" or F- joint, is a processing technology and connection method that two or more materials (the same or different) are heated and pressurized, or both are used to produce atomic bonding between two workpieces. Welding is widely used, which can be used for both metals and nonmetals.

Question 8: What are the types of welding and how to distinguish the welding forms? There are mainly the following types: (1) gas welding. The so-called gas welding is to use the high-temperature flame produced by the mixed combustion of oxygen and acetylene gas to weld the base, so gas welding is also called oxygen acetylene welding or gas welding. (2) Arc welding. Electric arc is used to convert electric energy into heat energy, so that covered electrode metal and base metal can be melted to form a weld. Welding machines used in arc welding are divided into AC welding machines and DC welding machines, and AC welding machines are mostly used to weld carbon copper pipes. DC welder is mainly used for welding stainless acid-resistant steel and low alloy steel pipes. (3) argon arc welding. This is a welding method using argon as shielding gas. In the welding process, argon gas forms a gas protective layer around the arc, so that the welding position, tungsten electrode gap and welding wire are not in contact with air. Because argon is an inert gas, it does not react chemically with metals, so the alloy elements in weldments and welding wires are not easy to be destroyed during welding, and because argon does not melt in metals, there will be no pores. (4) argon arc welding. There are two different welding methods for the bottom and upper part of the weld, namely argon arc welding is used for backing the bottom of the weld and arc welding is used for covering the upper part of the weld. This welding method can not only ensure the weld quality, but also save money.