How to brew cast iron with a semi-automatic machine

Welding cast iron semi-automatically

Cast iron is widely used for the manufacture of pulleys, blocks, and commutators. It has good casting properties, which makes it possible to produce products of various shapes from it. But this material also has disadvantages - it is quite fragile.

Impacts often cause chipping of sides on pulleys or cracks in pipes. To correct the situation and restore the product, they resort to various methods of joining metals. One of them is semi-automatic welding of cast iron.

What are the features of this method? How many options are there for using a semi-automatic machine? What supplies are suitable?

Why is it difficult to cook cast iron?

The question of whether it is possible to cook cast iron with a semi-automatic machine worries many people for good reason. The connection of the sides of this material does have a number of specific features:

1. The high fluidity of cast iron manifests itself when forming a seam where the weld pool is too liquid. Because of this, it is more difficult to visually control the quality of compound formation. When trying to weld thin plates of cast iron, a common defect is metal burning and droplets leaking onto the opposite side. To prevent these undesirable manifestations, graphite pads are used to support the plates on the reverse side. You can learn how to form a seam when the metal has high fluidity by practicing on training products made of similar alloys.
2. The second difficulty is the low melting point of the material. Due to the high temperature from the electric arc, the cast iron in the welding zone quickly overheats. As a result, upon cooling, microcracks form between the base and superimposed metal. Overheating of additional impurities in cast iron (manganese, silicon) leads to the appearance of cementites in the weld structure, which complicates subsequent processing of the joint with grinding tools. To prevent these defects, they resort to preheating the material and a gradual cooling procedure for the product.
3. It is difficult to weld cast iron efficiently due to the large number of pores that appear as a result of the release of carbon when interacting with oxygen. Even with subsequent processing, the seam may have an unattractive appearance and poor resistance to fracture. To protect the connection, copper-plated wire is used, and the work is carried out in an inert gas environment. A prerequisite for welding cast iron is the flux content in the wire.

Welding methods

Depending on the purpose of the product, three types of semi-automatic welding of cast iron are used. They differ in the speed of work completion and material costs.

Cold method

This is the easiest way to quickly join high carbon iron plates. Welding is performed immediately on a material whose temperature is equal to the ambient temperature. The cold method is used on non-critical butt joints that will not be subject to loads.

The method is ideal for surfacing worn surfaces and machine parts made of cast iron. Thanks to the continuous wire feed, you can quickly arc and complete a large amount of work in a short time.

As you can see in the video on semi-automatic welding of cast iron, the result from the cold method is satisfactory.

The semi-hot welding process differs from the previous one in that the cast iron workpieces are preheated to a temperature of 350 degrees. For this purpose, forges are used, in which the heat from the coals creates the necessary conditions. This preparation contributes to a more gentle reaction of cast iron to the high temperature of the electric arc, resulting in the formation of fewer cracks in the heat-affected zone. The technology is used on products that experience some stress during operation.

Hot method

This method is used where a high-quality connection is needed that has high tear and fracture resistance. The product heats up to a temperature of 600 degrees. For this purpose, devices producing induction currents are used.

The cables are connected to the cast iron part, and a special measuring device signals the temperature reached. After this, semi-automatic welding is performed. To minimize cracks, after welding the product is left in the ash until it cools completely. Depending on the thickness of the structure, this period can reach 24 hours.

The method allows you to weld cast iron reliably and efficiently, but is characterized by high time costs and the need for additional equipment.

Equipment and consumables

To obtain good joints from difficult-to-weld alloys, any semi-automatic machines are used. The main criteria are compliance with the maximum current of the device required to penetrate a specific thickness of metal. The adjustable current and wire feed speed parameters are similar to welding conventional steel.

Wire is used with specialized markings: PP ANCH-1, as well as with numbers 2 and 3. Each number is intended for a specific method (cold, semi-hot, hot).

The wire has a tubular structure and contains flux powder inside, which protects the weld pool from exposure to oxygen. Enrichment of the applied metal with special impurities promotes high tensile strength of the seam and tensile strength.

Thanks to Anch wire, it is possible not only to eliminate minor defects in cast iron, but also to produce full-fledged seams that firmly connect this specific metal.

To weld cast iron, a gas supply is used, which additionally protects the weld pool. Depending on the purpose of the product and the amount of impurities in the alloy, you can use carbon dioxide in its pure form or its mixture with argon, where the latter will be 80%. The flow rate from the pressure gauge to the burner should be 6-11 liters. This will optimally protect the molten metal from displacing carbon.

Semi-automatic welding technology

When welding cast iron with a semi-automatic machine, regardless of the temperature conditions, it is necessary to properly prepare the material. If you need to weld a crack, it is important to make a preliminary cut with a grinder along the entire split line. This will allow the filler material to be fused deeper. It is recommended to drill the edges of the cracks to limit its continuation.

If the thickness of the plates is more than 5 mm, then cutting the edges at 45-60 degrees is necessary. When working with thin sheets (up to 3 mm), graphite preforming is used to prevent burns. The first seam is made with a smooth pass without oscillatory movements. The burner can be operated from top to bottom or from right to left, tilted 50 degrees. The distance between the nozzle and the surface is maintained within 6-8 mm. It is important that the welder can see the end of the wire.

It is rarely possible to brew cast iron the first time, so it is recommended to go through the seam in several layers. Subsequent passes can be made with transverse vibrations in order to bind the base and deposit metal more widely. After welding is completed, it is necessary to separate the slag formed during combustion of the flux-cored wire and ensure the quality of the result.

Semi-automatic welding of cast iron is quite popular due to its high productivity and good quality of connections. By choosing the right wire and temperature conditions, you can get a reliable connection on this “capricious” material.

Source: https://svarkalegko.com/tehonology/varim-chugun-poluavtomatom.html

Semi-automatic welding of cast iron: features and process technology

Cast iron is of interest both for the construction industry and for many areas of production.

Its unique combination of technical and physical properties makes it possible to produce wear-resistant small parts and critical monolithic structures for the layout of engineering structures. But in each case, one or another form of processing of this alloy is required.

The most accessible and modern method is semi-automatic welding of cast iron, which itself provides several options for thermal effects on the workpiece.

Features of welding cast iron alloys

This is not the most convenient metal in terms of accessibility to thermal melt. The difficulty of working with cast iron is determined by its following characteristics:

• Low melting point. The electric arc from the welding machine contributes to the release of high-density thermal energy, as a result of which the metal in the welding zone overheats. The workpiece can be deformed even in places that were not intended for processing, and impurities (silicon and manganese) also overheat.
• Risks of formation of a porous structure. The negative effect of oxygen on the structure of molten metal causes the possibility of the formation of various types of defects. Therefore, special gas environments are used to protect the workpiece from oxygen. In particular, semi-automatic welding of cast iron is practiced in a carbon dioxide environment as the most acceptable from the point of view of chemical reactions in the work area. But even this is not enough to minimize the risk of defects after welding. Experts recommend, as an additional condition for obtaining a high-quality seam, the use of wire with flux, which further reduces the effects of atmospheric air and stabilizes the arc.
• Melt fluidity. At high temperatures with a melting effect, cast iron quickly turns into a liquid state, which causes another set of difficulties. Generally, flowability becomes a problem in operations with thin-sheet workpieces, where there are risks of through-melting with complete deformation of the element. This problem is solved by using graphite pads that retain the shape of the workpiece.

Basics of semi-automatic welding

The main difference between semi-automatic welding (inverters) is the mechanization of the supply of consumables - electrode or wire. For this purpose, a special feeding unit can be used. Also during the work, a gas cylinder, a reducer and a burner are used. It is advisable to perform operations with cast iron in one of the following modes - MIG/MAG or TIG.

Less commonly used is the manual MMA processing method, which is characterized by high melt quality. On powerful inverters, semi-automatic cast iron welding technology makes it possible to connect parts with a total thickness of up to 10 cm. However, thick workpieces can impose a high responsibility on the performer himself.

This is especially true for the initial stage of arc ignition, when it is necessary to maintain the stability of the torch and at the same time prevent the electrode from sticking to the surface of the workpiece.

Welding technology without the use of pre-heating of the workpiece. From an organizational point of view, this is the most convenient method, but in terms of the quality of the result, it is inferior to the hot melt formation technique.

As a rule, semi-automatic cold welding of cast iron is performed with electrodes, the coating of which gives the seam additional physical and chemical properties, like flux. Typically, electrodes containing copper, iron, and nickel are used.

This coating, under thermal influence, forms a structure protected from carbon inclusions, which improves the quality of the connection. It is recommended to use the cold welding method when working with large building structures.

Hot welding

It is unlikely that this method can be implemented at home, since preheating requires reaching temperatures of about 400-600 °C. By the way, induction furnaces are used in industry for such purposes. Working with heated products is technically easier in many ways, but the main task of such preparation is to improve the quality of welding.

Hard-state and at the same time brittle alloys can exhibit structural sensitivity to increased temperature influences, so parameters such as the accuracy of the direction of the torch and the correctness of the connection between the electrode and the workpiece come to the fore. Semi-automatic hot welding of cast iron and steel allows you to connect elements with a clean seam and a minimum content of defective areas. After the process is completed, the workpieces are slowly cooled.

Waiting for up to several days is required to ensure that no cracks appear in the joint area.

Regardless of the welding method and equipment used, cast iron workpieces require special preparation. Its surfaces must be cleaned of dirt, oil stains and, if possible, scale with traces of corrosion must be removed. Next, use a chisel or angle grinder to expand the edges along the entire length.

If you plan to repair cracks by welding, then initially drill holes in the places where defects form. Using the created recesses, it will be easier to perform high-quality semiautomatic welding of cast iron with optimal penetration into the crack formation zone. Workpieces with a thickness of more than 5 mm are subjected to turning to obtain 50-60 degree angular chamfers along the edges.

Thin parts, as noted above, are welded using graphite pads, eliminating the risk of through burning.

Selecting wire for welding

Semi-automatic usually involves the use of wire. If the electrode is rather used as a means of modifying the structure of the seam, then the wire in the case of cast iron processing performs a protective function. Today, special types of wire are produced for this metal - for example, from a steel alloy marked PP ANCH-1 (for the cold method).

If you plan to endow the structure with special properties, then cored wire is suitable. Experts, in particular, praise combined composition options based on silicon, copper and nickel. Semi-automatic welding of cast iron with conventional aluminum wire about 1 mm thick is still relevant.

With such a consumable, you can service profile cast iron elements, as well as large metal structures at direct current.

What to consider when organizing a protective environment?

Two aspects need to be considered. Firstly, this is equipment that will provide gas supply to the burner. Secondly, the type and properties of the gas itself. For technical organization, you will need a cylinder with the appropriate filling and mounting and connecting fittings with a nozzle, gearbox and other necessary equipment.

As for the second aspect, balanced semi-automatic welding of cast iron in a carbon dioxide environment is the most common method. Carbon dioxide as such is self-sufficient and provides the necessary protection for welding. Another thing is that it does not always guarantee arc stability and does not perform well during high-precision work.

An alternative option would be an argon or carbon dioxide-argon mixture, which opens up more opportunities for producing modified alloyed alloys.

Semi-automatic cast iron welding process

Work begins with igniting the arc. The most comfortable option for performing this operation is offered in inverters with a piezo ignition function and subsequent flame control using Arc Force and Hot Start technologies. The holder must be held at a 60-degree angle relative to the working surface.

The suture is applied in several approaches - in layers. The final layers are laid with the tip of the wire across. The event ends with the removal of slag and adjustment of its temperature. To ensure gradual and uniform cooling, the workpiece is covered with non-flammable material like asbestos.

Conclusion

Semi-automatic welding methods contain many technological nuances that require different formats for carrying out work. Much depends on the gas environment and consumables.

For example, a semi-automatic cast iron welding wire can determine the ranges of optimal arc voltage and supplied current. But, of course, at a basic level one should proceed from the requirements for the target workpiece.

Its characteristics and the parameters of the planned seam are taken into account, and in production, the speed of the operation is also important.

Source: https://FB.ru/article/383577/svarka-chuguna-poluavtomatom-osobennosti-i-tehnologiya-protsessa

How to brew cast iron with a semi-automatic machine?

Cast iron is one of the most popular metals for making a variety of products: from car parts to water pipes. At its core, cast iron is carbon and iron, which in the right proportions form a very strong and durable metal. Cast iron parts can be found in factories and industries, and even old cast iron frying pans have served their owners for decades.

Despite many alternatives, cast iron is not slowing down and remains a very popular material. Therefore, a home or professional welder will sooner or later have to face the need to weld cast iron. In this article we will tell you in detail what features this metal has, how to weld cast iron correctly and how to carry out welding work on cast iron with maximum benefit.

Features of cast iron

Welding cast iron in a garage or in large-scale production has a number of nuances that need to be taken into account before starting work. There are not many of them, so we will tell you about them all.

Welding cast iron must be done in the lower position, since the metal is very fluid. Do not overheat cast iron when welding, otherwise pores are guaranteed to form, followed by cracks.

Also, when melting, cast iron releases a special gas, which negatively affects the formation of the weld. Therefore, welding of cast iron parts must be carried out quickly and in compliance with the temperature regime.

Do not overcool hot cast iron, otherwise cracks will form again.

In order to get a truly high-quality welded joint when working with this metal, take into account all the features and characteristics of the cast iron itself. Be sure to prepare the metal before welding, select the correct operating mode in your welding machine and use special electrodes. But we will talk about all this further; first, we will deal with the preparation of the metal, since this is where the technology of welding cast iron begins.

Preparatory stage

The preparatory stage is one of the most important, since the quality of further work depends on proper preparation. First, clean the surface of dirt, dust and corrosion (if any). Degrease the metal with acetone.

If you are welding thin cast iron, make sure you have a heat-dissipating pad in advance. Cut the edges using a file or grinder.

 If you have to weld cast iron parts using the hot method (a method in which the part is heated before welding), then use a stove or gas burner for this.

Inverter welding with consumable electrode

Now let's move on to welding methods. Cast iron is cooked at an average temperature, so it can be welded with an inverter machine right in the garage or at the dacha, not to mention the factory workshop.

Welding cast iron with an inverter is carried out using a consumable electrode, as well as with a welding machine and a cold method (a method in which the part is not heated in a furnace or manually using a torch before welding).

Consumable electrodes must contain nickel or copper. Below you can see a table with recommended settings for different electrodes.

It is allowed to make intermittent seams, but not shorter than 3 centimeters in length, you need to use a temperature of no more than 80 degrees Celsius and allow the cast iron to cool. Also set the polarity to reverse.

Welding with steel electrodes

Is it possible to weld cast iron with ordinary steel electrodes? You can of course try, but we don't recommend doing it, especially with arc welding. Yes, standard steel electrodes are cheap, but such a connection will be unaesthetic and short-lived. If you need to weld a critical part (for example, part of a water pipe), then it is better to use special electrodes and do not skimp.

Welding with cast iron electrodes

For cast iron, specialized cast iron electrodes are best suited. You can cook it either cold or hot, as you see fit. We often warm up the part before welding so that the metal structure becomes better and the seam is more reliable.

Using such electrodes, you can easily correct multiple defects in cast iron, such as cracks, holes or chips. Electrodes of the MNCh-1, OZCh-1 or OZB-2M brands are often used in work. They are not that expensive, but the quality of work is excellent.

Welding cast iron with an electrode at home is carried out using direct and alternating current. To correctly set the current value, look at how long your electrode is. 1 millimeter of electrode corresponds to 50 amperes.

Welding with non-consumable electrodes

Welding of cast iron parts with non-consumable electrodes is carried out in a shielding gas environment or using drill fluxes. Nickel, copper or aluminum filler wire can also be used. Carbon, tungsten or graphite rods are used as a non-consumable electrode.

In most cases, when using non-consumable electrodes, cast iron is welded with argon (so-called TIG welding). We recommend slightly heating the part before welding using a gas torch.

Set the welding current to a small value. Welding should be intermittent, 3 centimeters at a time.

After welding, you need to gradually cool the part and monitor the temperature to prevent overcooling and the formation of cracks.

Welding cast iron with argon is rarely used, since it requires not only an electrode, but also a gas cylinder, preheating of the part and careful cooling, and all this takes a lot of time. Also, semi-automatic welding of cast iron is more expensive than other methods, but when you have no other option, you can weld using this method.

Gas welding of cast iron

Gas welding of cast iron is a fairly popular method, since the work requires only flammable gas, oxygen, cast iron welding wire and flux. At the same time, the quality of the seams is very decent.

Welding wire for cast iron used in the work must contain flint. This is very important because silicon promotes the formation of graphite in cast iron and does not bleach the metal.

You can also use low alloy cast iron wire for better weld quality.

The use of fluxes when gas welding cast iron is simply necessary, especially if you are welding steel with cast iron. Cast iron and steel are generally very different metals, so an oxide film forms on the surface in large quantities.

Safety precautions

It is not enough just to know how to weld cast iron in order to get started right away.

Additionally, it doesn’t hurt to study safety precautions, especially for welders practicing their craft at home.

Use grounding means to avoid trouble. Do not expose the cast iron surface to moisture. And most importantly: use personal protective equipment, such as gloves, a mask, a special suit, and so on. Do not neglect safety precautions, because at critical moments it can save your life.

Instead of a conclusion

Welding cast iron with an electrode at home requires the master to follow the technology and take into account all the nuances of the metal itself. Take your time while working, use quality components and practice as much as possible. This way you can gain experience. Leave your comments and share this article on social networks. Good luck!

Source: https://varimtutru.com/kak-zavarit-chugun-poluavtomatom/

Connecting cast iron workpieces with a semi-automatic welding machine: hot and cold methods

Cast iron, despite its relative fragility, remains one of the most popular structural metals. This is facilitated by the hardness of the material, resistance to alternating and fatigue loads, and high heat capacity.

Features of technical equipment for the process of semi-automatic welding of cast iron

Welding cast iron is difficult due to the metal's tendency to develop defects and reduce performance characteristics when exposed to high temperatures.

To connect cast iron workpieces and eliminate faults in finished products (cracks, chips, etc.), a simple and fast method of semi-automatic welding is most often used, which, however, requires special equipment. MIG and MAG technologies are acceptable, which involve the supply of inert and active gases, respectively.

Basic equipment

For semi-automatic welding, specialized electromechanical devices are used, which provide a continuous supply of a consumable electrode to the weld pool, as well as protection of the seam from the harmful effects of atmospheric air using flux or gas. Simple “semi-automatic machines” have a single-body design, when the following are combined in a single module:

• welding power source;
• motor, gearbox and passive wire feed units;
• shielding gas injection system;
• device operation control system.

The external elements of such a device include primary and secondary cables, a gas cylinder with a pressure-reducing unit and a discharge hose, and a burner.

For large production volumes, as well as complex welding work, it is advisable to use modular semi-automatic machines. Their feed mechanism and gas system are located in a separate housing, and the welding power source with the control unit is located in the main module. If the device is designed for intensive use, the burner can be supplemented with a forced liquid cooling system.

Depending on the design of the primary power circuits, single-phase and three-phase “semi-automatic machines” are distinguished. The former are attractive due to their compactness and ease of connection to the network, since they operate on 220 V alternating current. The latter are used in industrial cycles and are powered by a 380-volt network. An equally important factor is the type of wire feeding mechanism. He can be:

• pushing – located inside the body of the device, pushes the welding wire into the sleeve, which in some cases (for example, when using thin or excessively soft material) can lead to jamming;
• pulling - located inside the torch handle, tightens the wire, ensuring its uniform feeding, which can sometimes lead to unwanted thinning of the material;
• combined - has both pushing and pulling units that act synchronously, and is characterized by stable and uninterrupted operation.

For hose lengths less than 4 meters, feed mechanisms with one pair of support rollers are usually used; for hoses longer than 4 meters, two pairs are used. If the hose length exceeds 8 meters, the only possible feed mechanism is a combination with two pairs of rollers.

Optional equipment

In addition to a semi-automatic machine, for welding cast iron you will need standard tools and materials for surface preparation and personal protection. These include:

• grinding machine (grinder);
• metal brushes;
• degreasing solution;
• dry clean rags;
• welding gloves;
• protective mask.

When welding with gas weld protection, you will need a cylinder with carbon dioxide, argon, helium or a mixture of gases. In some cases (for example, when welding cracks in cast iron crankcases), a hand drill with metal drills and other power tools can be used to pre-process the workpieces.

Filler wire

Semi-automatic welding of cast iron is carried out using a wire-type consumable electrode. The use of electrodes on steel is unacceptable, since in any case this will lead to cracking of the seam when it hardens. The choice of filler wire grade for cast iron depends on the welding mode:

• welding without heating (cold) – PP ANCH-1;
• welding with heating up to 350℃ (semi-hot) – PP ANCH-2;
• welding with heating up to 600℃ (hot) – PP ANCH-3.

The abbreviation “PP” in the wire marking indicates its powder type. This means that the material contains the necessary filler elements (Fe, Ni, Cu, Si, etc.) that provide the necessary strength and stability of the weld.

Approximate cost of cored wire on Yandex.market

Semi-automatic cast iron welding technology

When choosing a welding mode for cast iron, it is important to take into account a number of its physical and chemical features, which make it difficult to work with the material using classical methods. First of all, these include:

• low metal melting point;
• change in the structure of a substance under the influence of high temperatures (“bleaching”);
• high fluidity of cast iron , which increases the risk of burn-through and deformation of workpieces;
• the appearance of pores in the material under the influence of atmospheric oxygen.

This necessitated the use of gentle welding modes with constant protection of the seam by active or inert gas media. Cold and hot technologies for semi-automatic welding of cast iron have become widespread.

Cold way

Cold technology is used mainly in domestic conditions to create seams that do not withstand direct mechanical loads. It is simpler and cheaper, however, it does not provide a sufficiently high-quality connection of the workpieces. The algorithm of actions includes the following:

1. Joint processing , edging if necessary.
2. Fastening workpieces to the supporting surface with a gap of 1.5-2 mm.
3. Setting the semi-automatic CA to low DC mode with reverse polarity.
4. Ensuring the supply of shielding gas to the welding zone and ignition of the arc.
5. Welding the seam at an angle forward (the slope is 50-60°, which is enough for visual inspection).
6. The arc breaks and the supply of shielding gas stops (after 15-30 seconds).
7. Cleaning the seam from slag and mechanical treatment.

Unlike MIG and MAG welding of steel, working with cast iron does not require oscillatory and transverse movements of the electrode.

In addition, cold technology allows the application of a single-layer seam at the joints of parts up to 4 mm thick.

Hot way

The best quality of welds in cast iron is ensured by the hot method of semi-automatic welding, which is widely used in repair shops and sometimes in industrial complexes. It requires the following sequence of actions:

1. Joint processing , edging if necessary.
2. Preparing the supporting surface , installing a graphite lining on it.
3. Heating the workpieces in the oven to a temperature of about 600℃.
4. Fast fixation of workpieces to the backing and early start of welding with low direct current with reverse polarity in a protective gas environment.
5. Welding the seam at an angle forward (the slope is 50-60°, which is enough for visual inspection).
6. Repeated welding of the seam (depending on the thickness of the metal, from 2 to 5 layers are applied), during which the method of transverse guiding of the electrode is acceptable.
7. The arc breaks and the supply of shielding gas stops (after 15-30 seconds).
8. Cleaning the seam from slag , ensuring a slow decrease in the temperature of the part under a layer of asbestos, charcoal or other non-combustible material.
9. Final cleaning and mechanical treatment of the seam.

It is important to remember that the speed of semi-automatic welding is much higher than manual welding. If you have not worked with a semi-automatic machine before, practice on scrap cast iron before starting to weld critical joints.

Source: https://elsvarkin.ru/texnologiya/svarka-chuguna-2/

How to cook cast iron semi-automatically

Welding cast iron requires special attention from welders. This metal is brittle; seams are formed unreliable and loose due to the high carbon content in the alloy. Using surfacing technology, cast iron can be welded semi-automatically. Only first you need to properly prepare the surfaces to be welded and select the right wire. Experienced specialists will share their professional secrets.

Features of cast iron welding

When restoring cast parts, it is important not to overheat the work area so as not to burn the part. When rapidly cooled, the metal becomes whitish - the alloy loses strength due to structural damage. Cast iron is very fluid; through defects in thick parts are repaired by long-term surfacing. Cracks have to be cut down to the base. When metal is joined at high temperatures without a protective atmosphere, due to carbon burnout, the seam becomes loose, porous, and fragile.

Taking into account the peculiarities of welding cast iron parts, practitioners have developed several methods for restoring cast iron products. Almost all types of welding are applicable for this, the main thing is to choose the desired temperature regime. It is most convenient to deposit a carbon alloy using a semi-automatic machine.

Methods of welding cast iron

In order for the metal to retain its structure, it is heated locally or completely. If there are no special requirements for the strength of the connection, you only need to restore the integrity of the part by welding the metal without heating.

Semi-automatic welding of cast iron with conventional wire

Cast iron is one of the most popular metals for making a variety of products: from car parts to water pipes. At its core, cast iron is carbon and iron, which in the right proportions form a very strong and durable metal. Cast iron parts can be found in factories and industries, and even old cast iron frying pans have served their owners for decades.

Despite many alternatives, cast iron is not slowing down and remains a very popular material. Therefore, a home or professional welder will sooner or later have to face the need to weld cast iron. In this article we will tell you in detail what features this metal has, how to weld cast iron correctly and how to carry out welding work on cast iron with maximum benefit.

Semi-automatic welding of cast iron with conventional wire - Machine tools, welding, metalworking

Cast iron is widely used for the manufacture of pulleys, blocks, and commutators. It has good casting properties, which makes it possible to produce products of various shapes from it. But this material also has disadvantages - it is quite fragile.

Impacts often cause chipping of sides on pulleys or cracks in pipes. To correct the situation and restore the product, they resort to various methods of joining metals. One of them is semi-automatic welding of cast iron.

What are the features of this method? How many options are there for using a semi-automatic machine? What supplies are suitable?

Semi-hot method

The semi-hot welding process differs from the previous one in that the cast iron workpieces are preheated to a temperature of 350 degrees. For this purpose, forges are used, in which the heat from the coals creates the necessary conditions.

This preparation contributes to a more gentle reaction of cast iron to the high temperature of the electric arc, resulting in the formation of fewer cracks in the heat-affected zone.

The technology is used on products that experience some stress during operation.

DIY cast iron welding

Cast iron is one of the most popular metals for making a variety of products: from car parts to water pipes. At its core, cast iron is carbon and iron, which in the right proportions form a very strong and durable metal. Cast iron parts can be found in factories and industries, and even old cast iron frying pans have served their owners for decades.

Despite many alternatives, cast iron is not slowing down and remains a very popular material. Therefore, a home or professional welder will sooner or later have to face the need to weld cast iron. In this article we will tell you in detail what features this metal has, how to weld cast iron correctly and how to carry out welding work on cast iron with maximum benefit.

How to cook cast iron with a semi-automatic machine? — Metals, equipment, instructions

An alloy of iron and carbon, when the amount of the latter is more than 2.14 weight percent, is called cast iron. Thanks to its excellent casting qualities, it is widely used in various industries and heavy engineering.

When casting massive castings, surface casting defects may appear. One of the most common is the sink. Remelting a large mass of metal due to a minor notch on the surface is not justified.

Welding comes to the aid of production workers in such a situation, as it can cope with minor defects.

Using a semi-automatic machine for cast iron

Among the various types of welding, special attention is paid to semi-automatic welding. A conglomerate of gas argon and arc welding in one device allows you to weld cast iron parts and eliminate casting defects. Semi-automatic surfacing of cast iron makes it possible to restore a worn layer of almost any thickness while maintaining its properties.

Let us remind you that semi-automatic welding (MIG/MAG method) involves melting a special wire using an electric arc in a protective gas environment. The semi-automatic machine, using automation, feeds the wire into the welded area at a speed previously set by the welder. The protective gas environment avoids contact of oxygen from the environment and the metal molten bath.

Reducing the amount of slag and gas bubbles in the thickness of the frozen metal leads to an improvement in the quality and mechanical characteristics of the joint.

Semi-automatic welding allows you to cope with the assigned tasks of welding cast iron, regardless of its metal matrix structure, content and shape of carbon inclusions. These parameters divide cast iron into

• ferritic,
• pearlite,
• grey,
• malleable,
• high-strength with spherical graphite inclusions and others.

This fact requires a special calculation and approach when choosing semi-automatic welding modes, taking into account the different physical properties of the alloys.

Read also: Electrodes for welding cast iron - markings and selection rules

Let us highlight the main technological criteria for determining the operating conditions for welding an alloy, based on its chemical and physical properties, namely:

• this material, regardless of the structure and percentage of elements, is prone to the formation of thermal cracks in the border zone of the seam, as well as in the seam itself;
• Without choosing a special mode for joining cast iron, subsequent mechanical processing on machines and manual processing is difficult, cutting often leads to destruction of the seam;
• tendency to form porosity in the seam when the temperature requirements for heating the metal and the cooling rate after making the joint do not meet;
• applying a seam is difficult and is limited by the spatial location, type and brand of welding wire;
• the possibility of the appearance of refractory oxides in the area of ​​the molten metal bath;
• expansion of the seam in unexpected directions caused by rapid oxidation of silicon.

Methods for dealing with welding joint defects

Semi-automatic welding will help to avoid defects based on the listed factors. This type is effective when using the electroslag type of process and welding wire for cast iron with special additives.

If plates are used to fill the seam, they must be made of cast iron of the same type as the main elements being welded.

Sulfur in cast iron tends to move into the seam and form brittle eutectics at the grain boundaries, reducing the mechanical strength of the joint. In such cases, desulfurizing type fluxes with a high fluoride content are used.

Fluxes and additives help to achieve high quality welds when using a semi-automatic machine with the use of preheating, partial heating, or without it.

At the same time, it is not advisable to abandon non-oxidizing and fluoride fluxes for any type of semi-automatic welding.

A special feature of welding cast iron using the MIG/MAG method is a weld that is free of defects associated with internal stresses that arise during temperature phase transformations, the transition of metal from liquid to solid, and during the nucleation and growth of graphite crystals. Visualization of the quality of a welded joint is the absence of cracks and microcracks on the surface of the weld, the absence of cavities when removing the top layer of metal after machining.

A distinctive feature of welding cast iron with the induction of electric welding slag has always been the production of a weld that eliminates chilling of the metal matrix, hardened areas, and the absence or minimization of shrinkage cracks.

Semi-automatic welding of malleable and high-strength cast iron

Welding of critical components from special types of cast iron is carried out in a carbon dioxide environment with wires of the Sv-08GS, Sv-08G2S, Np-30GHSA grades, as well as flux-cored wire, without preheating the parts being welded and the surfaced areas.

• In order to reduce the mass of metal in the volume of the seam, the process must be carried out while maintaining an overlap of one third of the width of the bead. The direction of the arc should tend towards the molten metal. To minimize changes in the structure of the weld metal, it is recommended to use “cascade” welding using annealing rollers. It is this technological move that preserves the expected ferrite-pearlite structure without changes.
• Wire for welding cast iron grade Np-30GHSA creates martensitic, troostite, and austenite inclusions in the thickness of the weld, which increase the abrasion resistance of the deposited layers.
• Welding of high-strength cast iron with nodular inclusions of graphite with steel parts and workpieces occurs using Sv-08GS, Sv-08G2S wire in the starting connection. The last working layer, to improve the mechanical properties, it is better to fuse Np-30GHSA.

Semi-automatic welding of cast iron is a technology that has proven itself at various stages of production and repair processes. It allows you to reduce the amount of defects at the production stage of cast iron castings, extend the life of machines and mechanisms, reduce non-production downtime, reducing production costs and increasing production profitability.

Source: https://spb-metalloobrabotka.com/kak-varit-chugun-poluavtomatom/

Semi-automatic welding of cast iron - features and specifics, selection of wire for high-quality results

An alloy of iron and carbon, when the amount of the latter is more than 2.14 weight percent, is called cast iron. Thanks to its excellent casting qualities, it is widely used in various industries and heavy engineering.

When casting massive castings, surface casting defects may appear. One of the most common is the sink. Remelting a large mass of metal due to a minor notch on the surface is not justified.

Welding comes to the aid of production workers in such a situation, as it can cope with minor defects.

How to weld cast iron semi-automatically

I'm sure many people have a semi-automatic welding machine. Often such people wonder how to weld cast iron semi-automatically and is it even possible to do this? First of all, you need to know that cast iron is an alloy of iron and carbon. carbon in cast iron is at least 2.14% . By the way, carbon is also present in steel.

It is noteworthy that pure metal practically does not exist in nature, therefore steel, no matter how pure it is, contains a percentage of carbon. It is no more than 2.14%. Cast iron does not exist in nature. Cast iron is an alloy developed by humans. Given that cast iron contains a lot of carbon, it is reasonable to conclude that it will be brittle. Despite the fact that it is a strong metal, it is also fragile.

Many people who have worked as welders for many years believe that welding cast iron with a semi-automatic machine is unrealistic. However, such people are mistaken, because it is possible to weld cast iron using semi-automatic welding. To do this, you need to use a special flux-cored wire, which allows you to quickly and efficiently weld the cast iron product you need. This wire is called PP-ANCh-3 . It is best used with heating, because heating promotes the highest quality of welding.

Also, when welding, non-oxidizing and fluoride fluxes are used. This welding gives you the opportunity to obtain high-quality seams as quickly as possible and at low cost. Today, this welding wire has a great sales success due to its high quality, because many professional welders use only the best welding equipment.

As you can see, welding cast iron using semi-automatic welding is a simple process, however, when welding cast iron products you need to be careful and never allow the metal to overheat, because cast iron can develop a crack, and in the future, perhaps even split. Therefore, you need to be careful not to damage your product.

In addition to the fact that you can ruin the product, you can also simply waste time trying to do something after the metal has been severely overheated. How better it is to just be a little more careful and avoid many problems. However, if you do experience overheating of the metal, you need to protect it from even a drop of water, that is, under no circumstances should you allow the metal to cool suddenly.

In order to avoid such situations, it would be best for you to preheat the metal to be welded, and only then start welding it. Only welding must begin immediately after heating the cast iron to 600 degrees .

Welding after heating will help you avoid a sharp increase in the temperature of the metal and will allow you to weld without any threat.

By avoiding overheating of the metal, using welding wire PP-ANCH-3 and preheating the metal, you can quickly and conveniently weld cast iron using semi-automatic welding.

Cast iron, despite its relative fragility, remains one of the most popular structural metals. This is facilitated by the hardness of the material, resistance to alternating and fatigue loads, and high heat capacity.