most types of welding steels at home is not much difficulty in the presence of the necessary equipment.But if you plan to cook pig iron, which is in addition to the basic steel construction material, there may be some difficulty.The main failure in the process of welding cast iron with their hands is the low quality welded joint, due to intense metal hardening in the weld -Other words with increasing fragility of iron in this area and the appearance of cracks.
- iron as an alloy
- Features welding iron
- Getting Started
- Species welding iron
- hot welding iron
- Cold welding electrodes
- flame welding iron
as an alloy of iron
known as iron-iron alloy, the carbon content in it more - from 2 to 6%.This provokes high carbon content that the carbon in the cast iron, in contrast to steel, is idle.The iron also contains silicon, sulfur, manganese, and phosphorus, wherein the phosphorus and sulfur in the cast iron material is greater
example, carbon in the most widespread and applies the gray cast iron exists in the form of graphite inclusions (remember that iron is smeared), which also determines its not a good weldability.Also, carbon may be present as cementite.And depending on the type of additives are distinguished white, gray and ductile iron.
durability of black metal, to which rank and iron, making it the best material for producing gratings, gates, and home decorating items.Cast iron pipes and batteries, which today can be found in almost every home, though, and is replaced by a modern version, and the price falls welding cast iron, but the value of this material is not reduced by this.
welding cast iron Cast iron is widely used structural material, which is characterized by low cost, high workability and good casting properties.But the high friability and low strength cast iron provoke failure in operation of many parts made therefrom.
Welders practitioners believe that the poor weldability of iron is due to the structure of the structure of the material to break.Cast iron, which has a fine fracture gray color, welded lighter than cast iron, which has a kink different coarse-grained and dark in color.Welding actually not be oiled cast iron and cast iron, which are exposed to brutal environments.
The chemical composition, physical properties and the structure of cast iron refers to the limit weldable alloys.Therefore it is always necessary to consider the following features cast-iron welding:
- Iron - flowable material, so it is the welding is performed in the down position.
- When carbon burning in the weld formed pores.
- Low ductility leads to considerable internal stresses and the occurrence of quench structures that promote the formation of cracks.
- molten iron is oxidized to form a refractory oxide having a melting point higher than that of iron.
The main problem, which is often accompanied by electric welding and manual arc welding of cast iron - the emergence of cold cracks.Specialists who work with the material, carefully study the overall composition of pig iron, the presence and proportion of carbon inserts.Picking the correct mode of operation will avoid unpleasant consequences.
to technological measures, which are directed against cracking, include: the prevention of overheating when welding iron, which is achieved by using small diameter electrodes, conducting a small current welding or vrazbroc;reduction in stresses which occur as a result of shrinkage of weld metal cladding or produced in hot forging, and a decrease of weld iron.
Preparations for welding
Remember that immediately prior to welding, despite the method of welding cast iron, you should always do the preparation edges of parts that are connected to, or carve defective places.The edges are beveled by hand using a chisel or plumbing portable sanding disc with a flexible shaft.To avoid splits iron need srubyvat thin layers, because the chip thickness should be no more than 0.8-1 mm.
carve up defective places of pure metal with the use of chisels, knives, cutters, drills, the size of which depends on the dimensions of the defect, the product shape and the need to create a comfortable working environment.
When cutting a defective process of places on the details of the iron necessary to observe the following rules:
- lead strictly butchering of fracture.
- Zasverlivayut non-through crack at a distance of 10 mm from their ends a drill that has a diameter of 1-2 mm wider than the crack, and they cut down to the bare metal.
- through cracks need to carve one or two sides, all determined by the thickness of the metal and the convenience of cutting.
- on cracks that apart too close, made weld on a patch on holes.
During the infusion repair holes need to smooth out the edges, cutting down sharply angular protrusions chisel.Strip the surface of the part at a distance of 30 mm from the edges of the holes with emery wheel.Then cut mild steel sheet patch the desired thickness and shape.The patch should cover any hole on all sides by 15-20 millimeters.
To reduce the stresses that occur in the material during the process of welding cast iron at home, you need the patch flanged edges at an angle of 30 degrees.The patch is placed on the product to the flare cast iron material and welded overlap.
Species welding iron
arc welding cast iron production is carried out in conditions of hot manner in which the welded parts are preheated to a temperature of 650 degrees Celsius.There is a cold method, when parts are heated before welding to a temperature of only 250 ° or not heated at all.
hot welding iron
Technology Hot welding of cast iron is much harder to cool the solution, but it helps to get rid of the risk of formation of cracks in the transitional areas of joints.When welding try to evenly heat the surface of the product, because the cause of faults and fractures becomes excessively large temperature difference between the basic element and the weld.
before heating the parts should be fixed in a rigid frame, to eliminate the stress, which may result in the welding process to cracking.If the heating iron products is local, it is not necessary to use a rigid frame.Parts made heated by induction heating using a current of industrial frequency.In addition, you can heat them in the mountainous using flame or blow torches.
When welding defects that are located on the edges of the part or welding through the cracks, it is recommended to use a graphite mold, which prevents leaking from the weld pool of molten metal.Moulds made cook using graphite plates that connect the molding sand consisting of silica sand, that is wetted with water glass.Heated done to to occur uniformly cooling the finished product in order to prevent the occurrence of cracks.
Immediately before welding work is necessary to prepare the defective place - thoroughly cleaned from dust and dirt and split to form cavities to provide good access for manipulating the electrodes in the welding zone.
when working strictly follow the technology of welding iron: observe the volume of molten iron during welding and stir his end of the filler rod or electrode.Cool item is gradual.Brewed place should not be too quick to cool down, it should fill with charcoal, dry or cool the hot sand in the oven.Small parts cool 3 - 40 hours, larger - up to 5 days.To protect
deoxidizing bath and used fluxes boric basis - for example, technical anhydrous borax, calcined at a temperature of 400 degrees.This method of welding is today considered the most perfect quality.However, iron is hot welding and disadvantages - difficult working conditions and laborious process.
Cold welding electrodes
In normal conditions, when there is no special heating equipment, and the need for welding metal is episodic in nature, the best procedure is to cool the welding iron special electrodes.For this commonly used electrodes OZCH-2 with a rod of copper, covered with a special composition and electrodes IPM-2, a rod which is made of an alloy of nickel, iron, copper and manganese.
metal that is welded electrodes MOF-2, machining more amenable, but such electrodes are very scarce and expensive.Cheap electrodes are OZCH-2, they simply make unaided viewing a video of the welding iron.
electrode OZCH 2 - is a copper rod, which has an electrode coating containing 50% metal powder 27% marble, 7% fluorite, 4.5% silica, 2.5% ferromanganese, ferrotitanium 6%, 2.5ferrosilicon%, 0.5% ash.Do not be put off by the large number of components, for the manufacture of home-made electrode can use ready-made cover.
To create electrodes for welding cast iron material next.Strip lengths of copper wire before the application on the product surface and degrease any organic solvent.Cleave the coating with the iron of welding electrodes, and connecting it pulverized in a ratio of 1: 1 with a steel powder or small iron filings.
Then mix everything carefully to the watery glass.Vertically in the resulting creamy mixture obmoknite lengths of copper wire and pull them slowly from the coating mass to an excess of time to drain.In this case, the thickness of the coating layer should be not less than 1.5-2 mm.The electrodes are first dried in a vertical position in air and then at 250 degrees Celsius calcined, using, for example, an oven plate.
iron welding electrodes carried homemade rather short arc, using a constant current - on the reverse polarity.They are of mandatory breaks for cooling the metal to a temperature of 50 degrees.When the widths of the electrodes 3-5 mm welding current value reaches 90-180 amps.To ensure high quality welding, the seam is necessary to impose small portions that have a length of 30-50 mm, and prokovyvat immediately after welding, it prevents the occurrence of cracks in the weld.
If you do not have time to create electrodes, remember that the living conditions provide good results welding iron via combined copper-steel electrodes.Recent manufactured, navivaya top coated electrodes creates steaming steel helix of brass or copper wire that has a diameter of 1.5-2 mm.The weight of such a spiral should be 4-5 times greater than the weight of the iron rod electrode.
When using combination electrodes for cast iron cold welding technology can not be strongly heated welded parts made of cast iron, so the process is carried out on a small welding current small areas "randomly" with the forging hammer purchased seams and breaks to cool the workpiece.
flame welding iron
Although there are many types of welding cast iron is the most reliable gas welding, which allows to achieve high quality welding, which will be similar to the properties of the base material.Such techniques are generally used to eliminate damage, for example, attaching the severed portion of the structure, restoring the damaged aperture.
During the flame welding simply perform a more leisurely and uniform heating or cooling of parts made of cast iron.As a result, the boundaries of the seam and the weld metal created for graphitization of carbon the more suitable conditions, minimizing the possibility of internal stresses.
But usually the technology of manual arc welding of cast iron gas involves a heating of the product.Spend a local heating burner flame to the working process.As a filler metal made use cast iron bars.Lead welding ordinary or carburizing flame using fluxes of borax or consistency: 56% of borax, 22% potash and soda.
excellent result demonstrates the welding of cast iron material gas flame using brass rods with a melting point lower than that of the cast iron material.The process is carried out with the participation of the flux of borax or boric acid and borax, which are taken in equal amounts.The edges of the cracks that the split at an angle of 80 degrees, should be heated to a temperature of 900 degrees, the flux and sprinkle with tinned brass rod edge.All butchering then need to fill in brass, iron is not melting.
So called cast iron alloy of iron with the carbon content of which is 2 - 6.7%.It is this structure causes the occurrence of difficulties in the welding of cast iron.Due to the significant complexity of the process, especially for large-sized products, it is recommended to take into account particular pieces of cast iron welding and predominantly use the technology of cold welding.