How to weld rails using manual arc welding. High-quality welding of rail joints. Rail welding methods

The installation of railway lines is carried out using two methods: prefabricated and welded. The second is preferable because prefabricated joints reduce the speed of rolling stock. Welding of rails is carried out using several methods. When choosing a method for installing seamless lines, the weldability of the material and the cost of the work are taken into account. The most common are resistance and aluminothermic welding, there are other types. Each one is worth mentioning separately. The joints are welded using special equipment.

Railway profiles are made from high-carbon steels characterized by poor weldability. During heat treatment, cracks form on the metal and internal stresses arise. When welding rail strands, this is unacceptable; defects in the rail material can cause an accident.

To work you need:

• professional equipment;
• high-quality consumables;
• control devices that check the integrity of the seam.

To form a strong connection, thick-walled beams must be welded to their entire depth. After welding the joint, it is necessary to level the surface so that the seam does not collapse.

Types of rails

To select a welding method, the chemical composition of the alloy is taken into account. For each type of profile, GOST defines steel grades.

Methods for welding rail joints

When choosing a technology, the weldability of steels, their fluidity, and ductility are taken into account. An important factor is labor costs and the cost of equipment. Taking into account all the components, they decide how to weld the rails.

The following technologies are used to seal joints:

• electric arc;
• electrical contact;
• aluminothermic;
• gas press

Enterprises more often use thermite welding of rails, less often contact welding. Each technology has advantages.

Electric arc

Rail welding using electrodes is used for joints and strands. Using the bath method it is possible to obtain a strong connection. The ends are placed on a small elevation above the canvas with a gap of 14–16 mm in a special bath that holds the melt. An electrode with a diameter of 5 or 6 mm is placed vertically into the joint. When applying high-frequency alternating or direct current of direct polarity with a power of 300–350 amperes, depending on the thickness of the profile, the melt gradually fills the entire joint. A diffusion layer is created over the entire section. For welding rails, electrodes with the main type of coating are used:

• domestic SSNI 13/45 and SSNI 13/55,
• Japanese LB 52U.

They are pre-calcined: kept at a temperature of 180 – 230°C for 2 hours.

Advantages of electric arc welding:

• there is no need to use flux, the coating creates a layer of slag over the bath, it prevents oxidation;
• no preliminary cutting of ends is required;
• no additional effort is required to form a tight connection;
• availability; transformers, rectifiers and professional inverters are used as current generators.

After cooling the bath, the joint is cleaned, scale is removed, and the surface of the rail head is leveled.

Termite

The method is based on the ability of aluminum to reduce iron oxide with a large release of heat. mastered more than a century ago. When thermite is set on fire, a temperature of 1200 to 2000°C is created in the working area, depending on the chemical composition of the alloy. The reduced iron flows into a mold whose profile matches the rail.

In addition to iron and aluminum oxide, thermite contains alloying additives and small pieces of metal (they inhibit the chemical process). The slag formed during the melt floats up and is removed after the metal has cooled.

The most important advantage of the method is the high speed of thermite welding of rails. It is used for hardened and cold-rolled beams. It is used in the installation of main railway lines and tracks.

Gas press

Welding of rail joints using this method is carried out on ductile steels. The temperature in the area where the ends meet increases due to shear energy. It is released at high blood pressure. A high-quality connection is formed due to the homogeneity of the diffuse layer. To ensure a tight connection of the rails, the end is cut with a rail cutter. The metal is preserved with carbon 4 chloride or dichloroethane; the metal does not oxidize under the composition. The joint is heated to a viscosity temperature, under 10–15 ton pressure from a hydraulic press, the layers shift, the ends melt, and a diffuse layer is formed.

The main advantages of the gas press method:

• uniformity of chemical composition;
• no scale, the process takes place inside the profile;
• the ability to connect profiles of any configuration and thickness.

Electrocontact

Automatic technology is based on heating the joint due to a piercing electric arc generated under the influence of high currents of low voltage. Electric contact welding is carried out with self-propelled complexes MSGR-500, MS-5002, K-190 directly at the installation site or with a slight displacement of the branch. For different types of rail profiles, replaceable contact heads are used. The work is carried out using the method of continuous melting or pulsed heating of the rails.

Quality control of rail joints

Traffic safety depends on the strength of the joints, therefore, regardless of the welding method, rail joints are checked using any of the non-destructive testing methods. Seams made with manual welding equipment are especially carefully checked. In addition to the structure, the evenness of the rail head on which the wheel rests during movement is checked.

Even discarded or worn-out rails are a desirable acquisition for any thrifty homeowner. After all, a durable and corrosion-resistant rail can replace any metal beam.

However, the installation of structures made from this type of rolled metal is very difficult. Heavy rails require strong welds. Railway workers use a special thermite composition for these purposes. Well, in everyday life, special electrodes are needed for welding railway rails. And in this article we will describe just such products, with the help of which you can join the rails in any way convenient for you.

"Rail" electrodes

When deciding which electrodes to weld rails with, it is worth taking into account the thickness of a given type of rolled metal. Therefore, the source of filler material in the process of welding rails can only be special electrodes of the UONI series, intended for joining thick-bodied structures. Moreover, for welding rails, the “junior” representatives of this series are sufficient - electrodes UONI 13/45 and 13/55, which can be used to join workpieces made of high-carbon or low-alloy steels.

UONI 13/45 and 13/55 electrodes differ from other sources of filler material by their special flux (coating), which includes ferromanganese ores, graphite, silicon and other materials.

Thanks to this multi-component mix, a stable burning of the arc is ensured, transmitting high temperature to the welding zone, and the process of pore formation in the welding seam is suppressed. The composition of the electrode wire is also interesting. It is made from an iron-carbon alloy alloyed with nickel and molybdenum. Wire diameter is 2-5 millimeters.

As a result, based on the special composition of the flux and filler material, the UONI series provides not only high speed of operation, but also no less high strength of the welding seam.

Preparing the electrode for welding

Electrodes for welding rails - work in very difficult conditions. After all, the thickness of the joining edges in this case can be several tens of centimeters.

Therefore, special requirements are placed on the quality of such electrodes, namely:

• There should be no large cracks in the coating of such electrodes.
• The humidity of the coating must correspond to a certain value.

And if the compliance of the electrode with the first requirement can be checked visually, then with humidity everything is much more complicated.

Therefore, before welding, all electrodes from the UONI series are subjected to mandatory calcination (drying) in a special installation.

This procedure looks like heating the product to a temperature of 350-400 degrees Celsius. Moreover, the electrodes are loaded into an already heated “oven” and “languished” in it for about 1-2 hours.

After such preparation, the electrodes can be used in any position, using them to form bottom, ceiling, and vertical seams on direct current and reverse polarity connections.

The only “contraindication for use” for the UONI series is welding from top to bottom.

Welding of rail joints is in great demand today. As is known, when rolling stock passes prefabricated joints, they begin to deteriorate at high speed. At the same time, the smooth running disappears, which is why the top covering of the railway track is destroyed. And this option will help correct the situation.

Main characteristics

It is required to lay rail tracks that have welded joints on any type of track, resulting in a seamless rail.

The rail thread breaks precisely in the places where the joint is formed. Such a gap, even when installing butt plates, has a great impact on the rigidity of the structure, and subsidence begins to increase.

As a result, when rolling stock passes a rail joint, the wheel hits the head of the end of the receiving rail. Due to numerous impacts on the butt joints, the running gear of the cars, as well as the laid rails, begins to wear out quickly. Due to the strong impacts of the wheel pair on the oncoming rail, the rail heads become chipped and crushed. Typically, such defects are found 60 cm from the joint. The rails begin to break in the bolt holes, the linings bend, and the butt bolts become deformed. All of the listed disadvantages do not apply to the seamless path, and it has several positive qualities:

• rail track maintenance costs are reduced by almost 30%;
• Electricity is significantly saved, fuel consumption is reduced by about 10%;
• the service life of the upper tracks increases,
• rolling stock can operate much longer;
• passengers experience greater comfort when the train moves;
• The operation of automatic locking and electrical circuits becomes more reliable.

Due to such positive qualities, the seamless option has been adopted by all the main railway lines in the world.

Sometimes the choice of a particular type depends on the cost of work and productivity. This choice entails the appearance in particularly critical structures of welding joints, the quality of which is at a very low level.

Read also:

Return to contents

To obtain an excellent weld joint, you need to have a material with good weldability. Basically, weldability characterizes the properties of the metal, the existing reaction to the welding process, as well as the ability to obtain a welding joint that will meet all specified technological requirements.

When the parts are made of a material that can be easily welded, no special conditions are required to obtain a high-quality seam. But for parts made of poorly weldable material, additional technological conditions are required. Sometimes a special type of welding is used, which is much more expensive and complex. Moreover, the execution of work requires strict adherence to the technological process.

Welding of rails is in demand today because the rail thread breaks and the running gear of cars quickly wears out.

Rail steel contains a lot of carbon, almost 82%. This material belongs to the group of materials with poor weldability. When welding, cracks may appear, which is completely unacceptable on rails. They concentrate stress, which can lead to the destruction of the butt joint and the collapse of the composition.

Today there are two types of welding of rail joints:

• contact;
• aluminothermic.

It has become widespread, but it has several serious disadvantages and limitations when repair work on railway tracks is carried out:

• welding requires special rail welding machines, which are very expensive;
• the duration of equipment delivery and its subsequent evacuation;
• to carry out the work it is necessary to involve numerous teams;
• in the absence of a large amount of time, you have to constantly perform work without following the technological process, as a result of which the joint is of very poor quality;
• It is impossible to weld the joint directly in the place where the arrows point.

Contact welding of joints is inferior to aluminothermic welding of rails. For it you need to have:

• complex and very expensive equipment;
• a large brigade;
• interruptions during train movement.

Aluminothermic welding of rails is done very quickly. The operation takes approximately half a minute. If you count the preparatory work and final processing of the weld, it takes about 45 minutes.

It must be said that such welding allows you to simultaneously weld several joints, as a result, the time spent on work is reduced.

Three people are required to weld the joint. Their training takes place in the shortest possible time. The weight of the equipment used reaches 350 kg. For welding work, when aluminothermic welding is used and other special operations are carried out, autonomous fuel supply sources are used.

To carry out aluminothermic welding of rails, engineers created portable miniature equipment that can operate autonomously right in the floor.

Technologists were able to select a specific composition of the thermite solution and its granularity. This helped to achieve a thermite reaction that does not cause explosions, does not decay, and maintains the most optimal speed and temperature of all materials involved in the reaction.

Aluminothermic welding consists of several basic technological steps:

• initial high-temperature heating;
• final welding of rails.

People who carry out large-scale construction or are simply accustomed to doing everything powerfully, then they probably face the problem of welding rails. Welding rails is a problem because they have a large diameter and, as a result, create obstacles for comfortable welding. Therefore, to weld rails you need to use high-quality electrodes, which allow you to be completely confident in the quality of the welded product.

One of those electrodes that can be used for welding rails is are SSSI 13/45 or SSSI 13/55. Yes, indeed, UONI welding electrodes are an excellent choice for welding such thick-bodied structures as rails.

UONI electrodes are used for welding critical structures made of metal, when a metal seam is presented with high requirements for impact strength. Many professional welders recommend UONI electrodes for welding structures operating under loads, pressure and other environmental factors.

Welding with UONI electrodes allows us to obtain high-quality metal that is highly resistant to cracking and hydrogen content. Welding with UONI electrodes can be performed in all spatial positions. For welding, you need to use direct current of reverse polarity.

The material for the manufacture of UONI welding electrodes is welding wire Sv-08A, which fully complies with state standards adopted in our country. Small cracks are allowed on the surface of the coating of welding electrodes, which may be on the coating of the welding electrode. However, if the coating of the welding electrode is severely damaged, then you need to check in which place you store them, because due to moisture, you can damage the welding electrode.

The coating of UONI welding electrodes has some features that require mandatory calcination before use. Calcination of SSNI electrodes is carried out at temperatures from 350 to 400 degrees Celsius.

Calcination of electrodes before welding makes it easier to work with them and allows you to make the weld seam made by them more durable. Also, calcining or drying the electrodes at the specified temperature makes them less susceptible to moisture.

As you can see, the use of UONI welding electrodes allows for high quality welding. Thanks to their high quality and welding features, you can start welding rails in a short time.

When carrying out installation and repair work on sections of the railway track, as well as in similar conditions associated with laying rail lines, special welding technologies are used.

Features of rail welding technologies are expressed in increased requirements for the operational reliability of connections, as well as their resistance to mechanical loads.

Welding of rail joints belongs to the category of particularly important activities, the organization and implementation of which is impossible without the use of equipment and modern welding mechanisms.

The main types of welding technologies used in the installation and repair of rails are:

• electric contact welding;
• electric arc method;
• thermite treatment (aluminothermic welding of rails);
• modern gas-press welding.

Each of these methods has certain advantages and disadvantages. To become more fully acquainted with them, we will consider each of the listed welding methods in more detail.

Electric contact method

The electric contact approach to connecting rail joints is based on their strong heating and subsequent melting through an electric arc, which is formed by a significant low-voltage current.

To implement the method, special machine complexes are used that operate in automatic mode (MSGR-500, MS-5002 or K-190, for example).

Before welding, the rails to be processed are laid either directly on the tracks, or with a slight offset inside the branch or outside the track (at a distance of about 260 centimeters from its axis).

In this case, the welding mechanism itself moves along the restored thread, that is, it is a self-propelled rail welding station.

During its operation, replaceable contact heads of various types are used, providing the necessary welding modes (continuous reflow or intermittent heating of contacts).

Electric arc method

Non-contact arc welding is one of the most common methods used for mating rail joints.

According to this approach, the rails are first laid with a small gap, after which their ends are welded with metal electrodes melted through an arc discharge. This type of non-contact welding does not require the application of excess sedimentary pressure and is implemented using alternating or direct currents supplied from a mobile welding station.

The most effective way to perform arc welding of rails is the so-called “bathtub” method, according to which pre-cut rails across the longitudinal axis are laid strictly along the track line with a slight elevation and a gap of approximately 14-16 millimeters.

A working electrode is inserted between the ends of the rail blanks laid in this way, followed by passing a current of about 300-350 amperes through it.

As a result of this effect, the molten mass spreads evenly over the gap and completely fills it. To prevent it from flowing out, the gap between the rails is closed with special blocking barriers. Upon completion of welding, the resulting seams are ground over the entire joint area.

Thermite treatment

Aluminothermic technology has been tested by time. The use of thermite welding of rails is based on a reducing reaction that occurs when the base (aluminum) comes into contact with another component - iron oxide.

The resulting metal (reduced iron) at operating temperatures of about 2000 degrees is poured into a special fire-resistant form that matches the geometry of the rails being welded.

This reaction is accompanied by the release of a significant amount of thermal energy.

Welding rails using the thermite method began a very long time ago (from the mid-19th century), but since then this type of welding, due to the use of aluminum, began to be called aluminothermic.

It is important to note that the described chemical reaction after igniting a special high-temperature fuel (thermite) lasts only a few seconds.

In addition to the two components considered (iron and aluminum oxide), alloying additives and small steel particles are introduced into the working welded mixture, which slightly slow down or dampen the ongoing process. Additives are necessary to ensure that the steel in the welding zone acquires the required qualities and parameters characteristic of most rail products.

When considering the features of this type of welding process, it should be noted that upon completion of the reaction, the total chemical mass is divided into two fractions: liquid metal and light slag, which floats to the top of the mold.

Termitan technology allows the following types of track products to be connected to each other:

• surface-hardened rail blanks;
• volumetrically hardened joining parts of rails,
• rails that have not undergone special heat treatment in any combinations.

This type of welding ensures compliance with the requirements of the basic standards for high-speed rail lines, in terms of compliance with welding technology standards.

Gas press method

This welding technology is based on joining metal rail joints at relatively low temperatures (notably below the melting point), but at a sufficiently high pressure.

The main advantages of the gas pressing method include the homogeneity of the material structure in the welding zone, as well as the high strength of the resulting joint.

Thanks to the listed advantages, this method can effectively “cook” even very heavy and large railway products. Before welding, the ends of such rails are tightly joined to one another, after which they are cut simultaneously using a special tool (a rail cutting machine with a circular saw or a mechanical hacksaw).

As a result of preparatory operations, the required tightness of the end parts of the rails with high purity of the metal interface is ensured.

In addition, immediately before welding, the ends are treated with dichloroethane or carbon tetrachloride. At the stage of preparing the rails for welding, their ends are heated to the required temperature using special combination burners that ensure sufficient temperature is obtained.

After thorough heating, the ends of the rails are clamped using a specially designed hydraulic press and continue to heat up to 1200 degrees.

During the welding process, the torch bodies are slightly displaced relative to the joint being processed (they make small oscillatory movements). The frequency of such periodic movements, as a rule, does not exceed 50 vibrations per minute.

Simultaneously with these movements of the gas burner, the rails are compressed by a hydraulic press with a force of 10 to 13 tons, the exact value of which is determined by special calculations. As a result of this treatment, the welded metal at the joint is deposited by approximately 20 millimeters.

To implement the described technological chain, special gas pressing equipment (universal machines) is used.

Upon completion of the entire complex of gas welding operations, the finished joint is thoroughly cleaned of slag, and then returned to its normal appearance (they say that it is “normalized”).

So, the considered key methods for welding rail joints are applied in accordance with the technical requirements and conditions for carrying out repair and restoration activities.

Of all the approaches, aluminothermic welding stands out, as it best meets modern requirements for non-contact restoration of rails or laying railway lines. It is the thermite method that is most often used in the construction and repair of modern transport highways.