Welding material (welding wire)
1. Submerged arc welding wire
In submerged arc welding, the flux plays a role of protection and metallurgical treatment for weld metal. The welding wire is mainly used as filler metal, and alloy elements are added to the weld, and participate in metallurgical reaction.
(1) Welding wires for low carbon steel and low alloy steel there are three kinds of welding wires commonly used for submerged arc welding of low carbon steel and low alloy steel.
A. Low manganese welding wire (such as H08A): often used with high manganese flux for welding low carbon steel and low alloy steel with low strength.
B. Medium manganese welding wire (such as H08MnA, h10mns): mainly used for low alloy steel welding, can also be used with low manganese flux for low carbon steel welding.
C. High manganese welding wire (such as H10Mn2 h08mn2si): used for welding low alloy steel
(2) High strength steel wire
This kind of welding wire contains more than 1% Mn and 0.3% ~ 0.8% Mo, such as H08MnMoA and h08mn2moa, which is used for welding high strength low alloy steel. In addition, Ni, Cr, V and re can be added into the welding wire according to the composition and performance requirements of high strength steel to improve the weld performance. MN-MO welding wire, such as H08MnMoA, is mostly used for weld metal with tensile strength of 590MPa.
(3) Welding wire for stainless steel
The composition of welding wire used shall be basically consistent with that of stainless steel to be welded. When welding chromium stainless steel, hocr14 h1cr13 h1cr17 welding wire shall be used; when welding chromium nickel stainless steel, h0cr19ni9 hocr19ni9 welding wire shall be used Hocr19ni9ti and other welding wires; when welding ultra-low carbon stainless steel, the corresponding ultra-low carbon welding wire, such as hoocr19ni9, should be used, and the flux can be melting type or sintering type, which requires small oxidation of flux to reduce the burning loss of alloy elements. At present, sintered flux is mainly used to weld stainless steel in foreign countries, while smelting flux is still the main method in China.
2. Welding wire for gas shielded welding
Gas shielded welding is divided into inert gas shielded welding (TIG welding and MIG welding), active gas shielded welding (MAG welding) and self shielded welding. Pure AR is used in TIG welding and Ar + 2% O2 or Ar + 5% CO2 is generally used in MIG welding. CO2 gas is mainly used in MAG welding. In order to improve the technological performance of CO2 welding, CO2 + Ar or Co2 + Ar + O2 gas mixture or flux cored wire can also be used.
(1) TIG welding wire
TIG welding sometimes does not add filler wire, which is directly connected after the base metal is heated and melted. Sometimes, filler wire is added. Because the shielding gas is pure AR, which has no oxidation, the composition of the welding wire does not change after melting, so the composition of the welding wire is the composition of the weld. Some use base metal composition as welding wire composition to make weld composition consistent with base metal. TIG welding has the advantages of small welding energy, good weld strength, plasticity and toughness, and can easily meet the performance requirements.
(2) MIG and MAG welding wires
MIG method is mainly used for welding high alloy steel such as stainless steel. In order to improve the arc characteristics, the MAG method is to add appropriate amount of O2 or CO2 into Ar gas. When welding alloy steel, using Ar + 5% CO2 can improve the anti porosity ability of weld. However, Ar + 5% CO2 gas mixture can not be used in welding ultra-low carbon stainless steel, only Ar + 2% O2 gas mixture can be used to prevent weld carburization. At present, MIG welding of low alloy steel is gradually replaced by MAG welding of Ar + 20% CO2. In MAG welding, the content of Si, Mn and other deoxidizing elements in welding wire should be appropriately increased due to the oxidation of shielding gas. Other components can be consistent with or different from base metal. When welding high strength steel, the content of C in the weld is usually lower than that of the base metal, while the content of Mn should be higher than that of the base metal. This is not for deoxidation, but also the requirement of the alloy composition of the weld. In order to improve the low temperature toughness, the content of Si in the weld should not be too high.
(3) CO2 welding wire
CO2 is an active gas with strong oxidizability, so the welding wire for CO2 welding must contain high deoxidation elements such as Mn and Si. CO2 welding usually uses C-Mn-Si welding wire, such as h08mnsia, H08Mn2SiA, h04mn2sia, etc. The diameter of CO2 welding wire is generally 0.891.01.21.62.0mm. Wire diameter ≤ 1.2mm belongs to fine wire CO2 welding, wire diameter ≥ 1.6mm belongs to thick wire CO2 welding.
H08Mn2SiA welding wire is a kind of widely used CO2 welding wire. It has good process performance and is suitable for welding low alloy steel below 500MPa. For the steel with higher strength grade requirements, h10mnsimo and other brands of welding wire containing Mo element should be used.
3. Electroslag welding wire
Electroslag welding is suitable for medium plate and thick plate welding. Electroslag welding wire is mainly used as filler metal and alloying.
4. Welding wire for nonferrous metals and cast iron
The first two letters "HS" in the brand name indicate non-ferrous metal and cast iron welding wire; the first digit in the brand name indicates the type of welding wire, and the second and third digits in the brand name indicate different brands of the same type of welding wire.
(1) Surfacing welding wire
At present, there are mainly two kinds of hard alloy welding wires for surfacing: high chromium alloy cast iron (solmait) and cobalt base (Stellite). High chromium alloy cast iron has good oxidation resistance and cavitation resistance, high hardness and good wear resistance. However, cobalt based alloy can maintain high hardness and good corrosion resistance at 650 ℃. Among them, the toughness of low carbon and low tungsten is good; the hardness of high carbon and high tungsten is high, but the impact resistance is poor.
Although the production efficiency of oxygen acetylene surfacing is low, the equipment is simple, the melting depth is shallow, the melting amount of base metal is small, and the surfacing quality is high, because it is widely used.
(2) Copper and copper alloy welding wire
Copper and copper alloy welding wire is commonly used for welding copper and copper alloy, and brass welding wire is also widely used for brazing carbon steel, cast iron and cemented carbide tools. Many welding methods can be used in the welding of copper and copper alloy. The correct selection of filler metal is the necessary condition to obtain high quality weld. Oxygen acetylene gas welding should be used together with gas welding flux.
(3) Aluminum and aluminum alloy welding wire
Aluminum and aluminum alloy welding wires are used as filler materials in argon arc welding and oxygen acetylene gas welding of aluminum alloy. The selection of welding wire mainly depends on the type of base metal, crack resistance, mechanical properties and corrosion resistance of butt joint. In general, the welding wire with the same or similar composition as the base metal is used for welding aluminum and aluminum alloy, which can obtain better corrosion resistance; but when welding aluminum alloy with high hot cracking tendency and heat treatment strengthening, the selection of welding wire mainly starts from solving the crack resistance, and the composition of welding wire is very different from that of base metal.
(4) Cast iron welding wire
It is mainly used for repairing cast iron by gas welding. Because the oxygen acetylene flame temperature (less than 3400 ℃) is much lower than the arc temperature (6000 ℃), and the hot spot is not concentrated, it is more suitable for the welding repair of gray cast iron thin-walled castings. In addition, the evaporation of nodularizing agent can be reduced when the flame temperature of gas welding is lower, which is beneficial to obtain nodular cast iron structure. At present, there are mainly two kinds of welding wires for gas welding: magnesium alloy with rare earth and yttrium based heavy rare earth. Because yttrium has a high boiling point, its ability to resist spheroidization is stronger than magnesium, which is more conducive to ensure the spheroidization of weld, so it is widely used in recent years.
Selection of flux cored wire
1. Types and characteristics of flux cored wire
According to the structure of welding wire, flux cored wire can be divided into seam welding wire and seamless welding wire. Seamless welding wire can be plated with copper with good performance and low cost, which has become the development direction in the future.
According to whether there is shielding gas, flux cored wire can be divided into gas shielded wire and self shielded wire; the composition of powder in the core of flux cored wire is similar to that of electrode coating, including arc stabilizing agent, deoxidizer, slagging agent and alloy agent; according to whether there is slagging agent in the filler powder in the inner layer of flux cored wire, it can be divided into "powder type" wire and "metal powder type" wire; according to the basicity of slag, it can be divided into two types The welding wires are titanium type, titanium calcium type and calcium type.
The weld bead of flux cored wire with titanium mold slag has good appearance, good welding performance, stable arc and small spatter, but the toughness and crack resistance of weld metal are poor. On the contrary, the weld toughness and crack resistance of calcium slag flux cored wire are excellent, but the bead forming and welding process properties are slightly poor. Titanium calcium slag is between the two.
The welding process performance of "metal powder" flux cored wire is similar to that of solid cored wire, and its deposition efficiency and crack resistance are better than that of "powder" flux cored wire. Most of the powder core is metal powder (iron powder, deoxidizer, etc.), and special arc stabilizer is added to ensure less slag formation, high efficiency, small spatter, stable arc, low diffusive hydrogen content in weld and improved crack resistance.
The section shape of flux cored wire has a great influence on the welding process and metallurgical properties. According to the cross-section shape of flux cored wire, it can be divided into simple O-shape and folding shape of complex cross-section. Folding shape can be divided into plum shape, T-shape, E-shape and middle filling wire shape.
The more complex and symmetrical the cross-section shape of flux cored wire is, the more stable the arc is, and the more sufficient the metallurgical reaction and protection of flux cored wire are. However, with the decrease of wire diameter, the difference gradually shrinks. When the wire diameter is less than 2mm, the influence of cut shape is not obvious.
Flux cored wire has good welding process performance, good weld quality and strong adaptability to steel. It can be used for welding various types of steel structures, including low carbon steel, low alloy high strength steel, low temperature steel, heat-resistant steel, stainless steel and wear-resistant surfacing. There are two kinds of shielding gases: CO2 and Ar + CO2. The former is used in common structures, while the latter is used in important structures. Flux cored wire is suitable for automatic or semi-automatic welding, DC or AC arc are required.
2. Flux cored wire for low carbon steel and high strength steel
This kind of welding wire is mostly titanium slag, with good welding technology and high welding productivity. It is mainly used in shipbuilding, bridge, construction, vehicle manufacturing, etc. There are many kinds of flux cored wires for low carbon steel and high strength steel. From the weld strength level, flux cored wires with tensile strength of 490mpa and 590MPa have been widely used; from the performance point of view, some focus on process performance, some focus on weld mechanical properties and crack resistance, some are suitable for all position welding including downward vertical welding, and some are special for fillet welding.
3. Stainless steel flux cored wire
There are more than 20 kinds of stainless steel flux cored wire, including chromium nickel stainless steel flux cored wire and chromium stainless steel flux cored wire. The diameter of welding wire is 0.8, 1.2 and 1.6 mm, which can meet the welding requirements of stainless steel sheet, medium plate and thick plate. Most of the protective gas used is CO2, and the mixture of Ar + (20% ~ 50%) CO2 can also be used.
4. Flux cored wire for hardfacing
In order to increase the wear resistance or obtain some special properties on the metal surface, a certain amount of alloying elements need to be transferred from the welding wire. However, the welding wire is difficult to be manufactured because of its large amount of carbon and alloying elements. With the advent of flux cored wire, these alloy elements can be added to the flux cored wire, and the processing is convenient. Therefore, it is a common method to use flux cored wire for submerged arc surfacing wear-resistant surface, and has been widely used. In addition, by adding alloy elements into the sintered flux, the surfacing layer with corresponding composition can be obtained after surfacing. It can meet different surfacing requirements when combined with solid or flux cored wire.
The common methods of CO2 surfacing with flux cored wire and submerged arc surfacing with flux cored wire are as follows.
The welding efficiency of this method is 3 ~ 4 times higher than that of manual arc welding; the welding process performance is excellent, the arc is stable, the spatter is small, the slag is easy to remove, and the surfacing forming is beautiful. This method can only be used for flux cored wire transition alloy elements, and is mostly used for surfacing layer with low alloy composition.
The flux cored wire with large diameter (3.2 mm, 4.0 mm) is used for submerged arc surfacing. The welding current is large and the welding productivity is improved obviously. When the flux is used, the alloy elements can be transferred through the flux to make the surfacing layer obtain higher alloy composition, and the alloy content can vary from 14% to 20% to meet different requirements. This method is mainly used for surfacing the wear-resistant and corrosion-resistant parts such as rolling roll, feeding roll and continuous casting roll.
5. Self shielded flux cored wire
Self shielded flux cored wire is a kind of welding wire that can be used for arc welding without shielding gas or flux, so as to obtain qualified welding seam. Self shielded flux cored wire is to put the powder and metal powder used for slagging, gasification and deoxidation into the steel sheet or coated on the surface of the welding wire. During welding, the powder turns into slag and gas under the action of arc, so as to play the role of slagging and gasification protection without additional gas Body protection.
The deposition efficiency of self shielded flux cored wire is obviously higher than that of electrode. The flexibility and wind resistance of field welding are better than that of gas shielded welding, and it can be welded under four wind forces. Because there is no need for protective gas, it is suitable for field or high-altitude operation, so it is mostly used in installation site and construction site.
The weld metal plasticity and toughness of self shielded wire are generally lower than those of flux cored wire with shielding gas. At present, self shielded welding wire is mainly used in low carbon steel welding structure, not suitable for welding high-strength steel and other important structures. In addition, when welding with self shielded welding wire, there is a large amount of smoke and dust, so ventilation should be strengthened when working in narrow space.
The company can order welding wire varieties according to customer needs.
