Welding seams classification and characteristics. Classification of welds and joints. Geometry and classification of welds

The basis of the welding process is the joining of metal elements and parts made of other materials by melting their edges. The place of joining of elements is a seam, the art of which is the main one for any welder. In the welding process, various types of connections of elements and welds are used, the choice of which is regulated by the conditions and requirements for welding.

If you intend to master welding, then first of all you need to understand what seams and joints are.

Welding joints are understood as the way in which the parts are connected for welding. There are several main types, the use of which allows you to dock any elements:

Butt;
Corner;
Tavrovoe;
End;
With rivets.

Welds- These are methods of welding metal elements, representing the way in which parts will be connected to each other. The types of welds are distinguished by different characteristics, exciting the way of joining parts, the requirements for the element being created, the thickness of the parent metal, etc.

Classification of welds

Welding work involves a wide variety of welds and joints. The types of welds can be distinguished according to a variety of characteristics. Let's present some of them:

Outwardly: concave, convex, flat. Concave ones give the completed connection some weakness, convex ones, on the contrary, are considered reinforced and are used when it is necessary to create a strong welded seam that is resistant to heavy loads;
By execution method: one-sided or double-sided. Welding can be carried out both from two sides (which is much more common, since it gives the part more strength), and from one side;
By the number of passes: single-pass and multi-pass. The latter are distinguished by their large size and strength;
By the number of welded layers: single and multi-layer. The latter are used when welding thick metals;
By length: point, chain, checkerboard, intermittent, solid. This characteristic reflects how the welded joint was made along the entire seam. Spot are typical for contact welding. The rest of the names speak of the length of the smaller seams, which form a longer main one;
In the direction of impact: transverse (the impact is perpendicular), longitudinal (the impact is parallel to the seam), combined (combines transverse and longitudinal), angular (the force is applied at an angle);
By functionality: strong, dense, sealed. This characteristic is associated with the further operation of the part, which dictates the need to follow special requirements;
By width: thread (the seam is equal to the diameter of the electrode) and expanded (created by oscillatory movements).

This classification represents an almost complete encyclopedia of types of welding methods.

It is necessary for a professional to know and be able to use them, for an amateur it is quite enough to master the basic types of welding seams, which are quite enough for welding almost all types of joints.

Varieties of welded joints

Let's move on to the types of welded joints, that is, how the parts to be welded are connected. There are several main varieties:

Butt method is the most popular and commonly used type. It is characterized by minimal internal stress and has the least probability of deformation during welding. Differs in high strength, sufficient for the operation of the product under dynamic and static loads.
The butt method represents the conjugation of the ends of two elements. If the metal sheets are rather thin, then they do not require preliminary preparation before welding. Thicker metal must be prepared by beveling its edges for a deeper weld. This rule works with a workpiece thickness of more than 8 mm. If the metal is more than 12 mm in thickness, then it is necessary to bevel the edges on both sides and make a double-sided connection. Welding is carried out in a horizontal plane.
Lap joint has a scope of application in the construction industry, where it is used in arc welding with a thickness of metal elements up to 12 mm. The metal does not require preliminary preparation, but it is important to ensure that no water gets between the elements. It is recommended to weld from both sides;
Corner connection allows you to weld elements at any angle to each other. For greater reliability of the seam, the edges of the parts to be joined are usually chamfered, which allows deeper welding. Also, the strength of the product is given by welding on both sides;
T-bar method used to create building elements (trusses, beams, etc.) representing the letter "T". Depending on which method was used, it can be one-sided or two-sided, elements of different thicknesses are often welded. Welding around the entire perimeter usually takes place in one step. Modern market offers devices for carrying out tee-mounting in automatic mode;
Riveted connection implies obtaining a sufficiently strong component. Holes are made in the upper element with a drill or otherwise, and through them the upper element is welded to the lower one. There are various types of riveted seams, among them the most common are those options in which rivets are used - special elements for fastening two parts;
End method implies the welding of two elements that are aligned with their ends. In this case, one element is at an angle to the other and is welded to one of its lateral planes.

The listed types of welded joints and seams have a detailed description and execution diagrams, which are given in GOSTs for welding.

Let's summarize

Knowledge of the types of joints and seams in welding is basic and provides the basis for applying welding skills in practice. This theoretical experience allows you to correctly choose the required type of joining of elements and the method of their welding, which will guarantee the resulting part the strength characteristics that are planned during its creation.

They are used both in low-rise construction and in the construction of large houses, office and sports centers. By welding, 2 or more parts are connected in 1. This creates a strong and reliable seam that can last a long time without breaking or causing damage to the part as a whole.

In addition, welded joints and seams can be used both for the joint of metal parts made of a homogeneous type of steel, and elements made of various alloys. With such complex work, it is necessary to choose the right welding technology, current strength, consumables (electrodes). In addition, the welder must have sufficient experience and skills to prevent burnout of the part, avoid unnecessary stress and deformation in further operation.

Classification of welds

All welded joints are standardized by special documentation that defines the concepts, areas and places of welding. The described terminology is applicable for technical documentation, which is attached at the end of the seams. The same concepts are indicated in the training and teaching aids, according to which the training of welders is carried out, as well as further training and improvement of their qualifications.

Weld Classification Table.

Using generally accepted abbreviations, even in the absence of documentation on the marking of the connection or a general specification, it is possible to determine what kind of welded joint is made in a particular place in the building structure. The following conventions are adopted: butt welded joints are usually denoted by the letter "C", when making an overlap - indicate "H", if T-joints are provided, then the specification is designated "T", corner - "U".

Basically, welding joints and seams should be divided according to several criteria:

By the appearance of the final cross-sectional shape:

Butt, that is, the parts to be welded are placed on the same plane.
Angular, when metal parts are at an angle to each other, while its value does not matter.
Slotted, if the parts superimposed on each other are mutually fused. In this case, one of the parts (upper) is completely melted, and the other part of the welded joint (lower) is only partially. The seam itself is a rivet. This connection is also called electro-riveted.

By configuration when welding:

straightforward character;
curvilinear appearance;
ring type.

By the duration of the welded joint:

Solid seam joints. Their length ranges from 300 mm to 1 m or more.
Which are performed intermittently. In this case, the location of the seam can be in a chain, in a checkerboard pattern, depending on design features details and requirements.

By the method of the applied welding technology:

arc welding without the use of additional means (gas, flux);
welding performed in an environment with the presence of gas (for example, argon).

By the number of welding elements applied:

unilateral;
two-way connection;
multilayer.

By the amount of metal formed as a result of fusion:

normal;
reinforced;
weakened.

There is usually no strict separation across all types of classifications. During operation, welded joints can be straight butt reinforced. That is, the combinations can be very diverse, depending on the complexity of the metal structure, requirements for rigidity and reliability, availability Supplies as well as the skill of the welder.

Characteristics of welded joints

The main types of welded joints.

Depending on how it should turn out in the end, it is necessary to take into account the peculiarities of its implementation and the technology of execution.

Butt welded joints are the connection of parts by fusing together. Parts are located in the same plane and arc welding is most often used. Moreover, such seams can be used to connect parts with different edges. The edge finish for welding depends on the thickness of the sheet. If, in the process of performing work, it is required to connect parts of different thicknesses, then the thicker edge should be beveled to the size of the smaller one. This ensures a secure seam.

By the type of edges that are involved in welding, butt welds can be divided into:

parts that do not have a beveled edge. They should be 3-5 mm thick;
elements that have a curved edge;
parts with an edge forming the letter "U", their thickness is 20-60 mm;
parts with an "X" edge, metal thickness 12-40 mm.

Learn more about connections

Butt welds have the lowest stress value and are less prone to deformation. This leads to their frequent use. When performing a butt joint, metal consumption is minimal, the preparation for work itself must be carried out carefully and scrupulously.

Tee elements are joints of metal parts, when one of them is located perpendicular to the other. It turns out a joint in the form of the letter "T". With this type, the seam itself can be located both on one of the sides, and on two. It all depends on the requirements of rigidity, technical and constructive ability to perform work. T-systems are used to assemble truss frames, different types columns, racks. In addition, such a connection is good for welding beams.

Corner joints are performed in cases where the elements in the structure will not carry significant stresses. For example, when welding tanks, tanks. To ensure the required reliability and strength, the thickness of the metal to be welded should not exceed 1-3 mm. When corner joining, the parts are applied to each other at the required angle and welded. The magnitude of the angle does not matter. The seam is made double-sided continuous so that moisture cannot penetrate into it.

Lap joints are formed when parts are parallel to each other. In this case, the seam is located on the side surfaces of the metal elements. Metal edges do not need additional processing, unlike the butt method. The consumption of both the base and the weld metal will be significant.

The thickness of the structure itself with such processing is no more than 12 mm. To exclude the penetration of moisture into the connection itself, it must be made double-sided.

Seams for T-shaped, overlapping, corner joints can be made in the form of small sections, that is, by the point method. If it is necessary to make preliminary surfacing, then they are performed in a round shape. Those. are formed when one of the parts is completely melted and partly the other.

Additional points

Known methods of performing arc welding without additional processing of edges can be produced with a metal thickness of 4 mm for manual work, 18 mm for mechanized work. Therefore, if it is required to weld parts of considerable thickness using a manual arc technique, then the edges must be additionally processed.

The elements of the geometry of the connection include the gap that is present between the elements, the angle of groove, bevel and the deviation of the parts involved in welding in relation to each other. The bevel angle determines the groove angle, which is decisive for providing the necessary arc access to the entire seam depth, which means that the seam itself is fully completed. The value of the angle, depending on the type of connection and the processing method, generally ranges from 20-60 ° with a tolerance of 5 °. The gap is 0-4 mm.

Welds and joints are classified according to various criteria. It is also important to understand that these are different concepts.

A weld is a place in a metal that is in a molten state during welding. And when the metal cools, the seam crystallizes. Welded joint is a broader concept. The joint directly includes the seam itself, as well as the adjacent zones, namely: the zone that was thermally affected during the welding process, the fusion zone, a part of the metal that is located near the zone that was heated.

It is important to distinguish between welds and joints, since the properties of the former determine the shape and strength of the metal in the place where welding took place. And the properties of the joint are determined by the properties of the seam itself and the rest of the joint zones, plastic deformations and, accordingly, affect the nature of the distribution of forces that will act in the welded joint.

It is also worth understanding that one welded joint may contain one or more seams.

In order to understand in what situations and for what work certain welds and joints are used, you should familiarize yourself in detail with their characteristics.

Types of welds and their characteristics.

The classification of welds is based on the following criteria:

Cross-sectional shape:

Butt - elements located in the same plane, butt ends and welded.
Corner - elements are welded at a certain angle.
Slotted - elements (sheets) are superimposed on each other and melted into each other.

The main difference is the different geometry and basic parameters of the seams. If, for example, at a butt seam, the main ones are the reinforcement height and width, then in the corner seam - the leg of the seam.

Weld Seam Configuration:

Straightforward.
Curvilinear.
Ring.

Weld seam length:

Solid ones are subdivided into short ones - their length is no more than 300 mm, medium ones - up to 1 meter and long ones - more than 1 meter.
Intermittent - they can have a chain and staggered arrangement of seams on a welded joint.

Welding method used:

Made with a consumable electrode manual arc welding.
Made in a gas environment with a consumable electrode.

Number of seam layers:

One-sided.
Double-sided.
Multilayer.

Deposited metal volume:

Normal.
Reinforced.
Weakened.

Welding joints: types and properties.

The main feature by which welding joints are classified is the arrangement of the elements relative to each other. Based on this, the following types are distinguished:

Butt joints - their formation is caused by the creation of butt-type seams.
Fillet welds are created when fillet welds are welded.
Overlap - these joints are also formed using fillet, as well as using slotted seams.
T-shaped - fillet seams are also used to create such joints, less often slotted ones.

Butt joints the most common, since they have the lowest stress value, and also the least amenable to deformation during the welding process. This type of joints is the least consumable for metal, but also requires the most careful preparation of parts before direct welding. With the help of butt seams, metal products with a thickness of 1 to 60 mm can be welded. For each thickness, there are recommendations for the shape of the bevel of the edges of the sheet - X-shaped, Y-shaped, U-shaped, and so on.

Corner connections- welding elements are located at any angle to one another, but do not carry much stress. Various vessels, containers, reservoirs are most often welded in this way. The thickness of the metal does not exceed 1-3 mm.

Lap joints- this type of connection does not require special processing of metal edges, as in butt welding, but the consumption of metal - base and weld-on will be large. The thickness of the metal for this type of welding is no more than 12 mm. Most often, a double-sided seam is used so that moisture does not penetrate from the opposite side of the seam.

Tee connections - truss frames, columns, posts, beams are most often welded using this type of connection. In cross-section, this connection is the letter T, and the weld can be both on one and on both sides.

Before starting any welding work, it is important to get an idea of what types of welds and joints exist. This information will help to efficiently use resources when performing work and will give an idea for which products it is preferable to use certain welds and joints.

Welded joints and seams are classified according to the following main characteristics:

type of connection;
the position in which welding is performed;
configuration and length;
the type of welding used;
a method for retaining molten weld metal;
the amount of overlapping layers;
material used for welding;
the location of the parts to be welded relative to each other;
the force acting on the seam;
the volume of the deposited metal;
the shape of the welded structure;
the shape of the prepared edges for welding

By the type of connection, welds are butt and fillet. According to their location in space, the seams of welded joints are subdivided into lower, vertical, horizontal and ceiling. The exit of the seam from the ceiling position to the vertical position when welding cylindrical products is called the semi-ceiling position.

According to the configuration, the seams of welded joints are rectilinear, circular, vertical and horizontal. In terms of length, the seams are divided into continuous and intermittent. Continuous seams, in turn, are divided into short, medium and long.

By the type of welding, the seams of welded joints are divided into:

arc welding seams
seams of automatic and semi-automatic submerged arc welding
gas shielded arc welds
electroslag welding seams
electric riveted seams
contact electric welding seams
solder joint seams

According to the method of retention of molten metal, the seams of welded joints are divided into seams made without backings and pillows; on removable and remaining steel supports: copper, flux-copper. ceramic and asbestos linings, as well as flux and gas cushions. Depending on which side the seam is applied, one-sided and two-sided seams are distinguished.

According to the material used for welding, the seams of welded joints are subdivided into seams of joints of carbon and alloy steels; non-ferrous metal joints; bimetal joint seams; seams between vinyl plastic and polyethylene.

According to the location of the parts to be welded relative to each other, the seams of the welded joints can be at an acute or obtuse angle, at a right angle, and also be located in the same plane.

By the volume of the deposited metal, normal, weakened and reinforced welds are distinguished.

According to the shape of the structure to be welded, the seams of welded joints are made on flat and spherical structures, and according to their location on the product, the seams are longitudinal and transverse.

Permanent joints made by welding are called welded. They can be butt, corner, overlap, tee and end (Fig. 1).

Butt joint is the connection of two parts with their ends located in the same plane or on the same surface. The thickness of the surfaces to be welded can be the same or differ from one another. In practice, the butt joint is most often used when welding pipelines and various tanks.

Corner - a welded joint of two elements located at an angle relative to each other and welded at the junction of their edges. Such welded joints are widely used in construction practice.

Overlapping - a welded connection provides for the imposition of one element on top of another in the same plane with partial overlap of each other. Such connections are most often found in construction and installation work, in the construction of farms, tanks, etc.

A T-joint is called a joint in which the end of the other joint is applied to the plane of one element at a certain angle.
Welding seams

The section of the welded joint formed as a result of the crystallization of the molten metal is called the weld. Unlike joints, welds are butt and fillet (Fig. 2).

A butt joint is a weld seam of a butt joint. A fillet is a welded seam of fillet, lap and tee joints.

Welding seams are distinguished by the number of overlap layers, their orientation in space, length, etc. So, if the seam completely covers the joint, then it is called continuous. If within one joint the seam is torn, then it is called discontinuous. A type of discontinuous seam is a tack weld, which is used to fix the elements relative to each other before welding. If the welds are placed one on top of the other, then such seams are called multilayer.

The shape of the outer surface of the welds can be flat, concave or convex. The shape of the weld affects its physical and mechanical properties and the consumption of electrode metal associated with its formation. The most economical are flat and concave seams, which, moreover, work better under dynamic loads, since there is no abrupt transition from the base metal to the weld seam. Excessive build-up of convex welds leads to overspending of the electrode metal, and an abrupt transition from the base metal to the weld seam at concentrated voltages can cause destruction of the joint. Therefore, in the manufacture of critical structures, the bulge on the seams is removed mechanically (cutters, abrasive wheels, etc.).

Distinguish welds by their position in space. These are bottom, horizontal, vertical and ceiling seams.

Elements of the geometric shape of the preparation of edges for welding

Elements of the geometric shape of the preparation of edges for welding (Fig. 3, a) are: angle of groove α; the gap between the abutting edges a; blunt edges S; the length of the bevel of the sheet L in the presence of a difference in metal thicknesses; offset of the edges relative to each other δ.

The groove angle is performed with a metal thickness of more than 3 mm, since its absence (grooving of the edges) can lead to lack of fusion along the section of the welded joint, as well as to overheating and overburning of the metal; in the absence of grooving to ensure penetration, the electric welder always tries to increase the value of the welding current.

Cutting the edges allows you to weld in separate layers of a small section, which improves the structure of the welded joint and reduces the occurrence of welding stresses and deformations.

The gap, correctly set before welding, allows full penetration along the cross-section of the joint when applying the first (root) layer of the seam, if the appropriate welding mode is selected.

The length of the bevel of the sheet regulates a smooth transition from a thick welded part to a thinner one; stress concentrators in welded structures are eliminated.

Blunting of the edges is performed to ensure a stable welding process during the root layer of the weld. The absence of bluntness contributes to the formation of burn-through during welding.

The displacement of the edges worsens the strength properties of the welded joint and contributes to the formation of lack of penetration and stress concentrations. GOST 5264-69 allows the offset of the welded edges relative to each other up to 10% of the metal thickness, but not more than 3 mm.

Geometry and classification of welds

The elements of the geometric shape of the weld are: for butt joints - the width of the seam "b", the height of the seam "h", with T-shaped, fillet and overlap joints - the width of the seam "b", the height of the seam "h" and the leg of the seam "K" (Fig. . 3, b).

Welds are classified by the number of weld beads - single-layer and multi-layer (Fig. 4, a); by location in space - lower, horizontal, vertical and ceiling (Fig. 4, b); in relation to the acting forces on the seams - flanged, frontal (butt) (Fig. 4, c); in the direction - rectilinear, circular, vertical and horizontal (Fig. 4, d).

Weld properties

The quality indicators of welded joints are imprinted by many factors, which include the weldability of metals, their sensitivity to thermal effects, oxidizability, etc. Therefore, for compliance of welded joints with one or another operating conditions, these criteria should be taken into account.

The weldability of metals determines the ability of individual metals or their alloys to form, with appropriate technological processing, joints that meet the specified parameters. This indicator is influenced by the physical and chemical properties of metals, the structure of their crystal lattice, the presence of impurities, the degree of doping, etc. The weldability can be physical and technological.

Physical weldability is understood as the property of a material or its compositions to create a monolithic connection with a stable chemical bond. Almost all pure metals, their technical alloys and a number of combinations of metals with non-metals have physical weldability.

The technological weldability of a material includes its response to the welding process and the ability to create a joint that satisfies the specified parameters.

The main types of welded joints. A welded joint is a permanent connection of parts made by welding. The following main types of welded joints are found in metal structures:

butt;
overlapping;
T-shaped;
corner;
end.

A butt joint is a welded joint of two elements adjoining each other with end surfaces.

Overlap - a welded joint in which the welded elements are parallel and partially overlap each other.

T-shaped - a welded joint in which the end of one element is adjacent at an angle and welded to the side surface of another element.

Corner - a welded joint of two elements located at an angle and welded at the junction of their edges.

End - a welded joint in which the side surfaces of the welded elements are adjacent to each other.

Classification and designation of welds. A weld is a section of a welded joint formed as a result of crystallization of molten metal or as a result of plastic deformation during pressure welding or a combination of crystallization and deformation. Welds can be butt and fillet.

A butt joint is a weld seam of a butt joint. A fillet is a welded seam of fillet, lap or tee joints (GOST 2601-84).

Welded seams are also subdivided according to their position in space (GOST 11969-79):

lower - into the boat - L;
semi-horizontal - PG;
horizontal - G;
semi-vertical - PV;
vertical - B;
semi-ceiling - PP;
ceiling - P.

According to the length, the seams are distinguished between continuous and intermittent. Discontinuous seams can be chain or staggered. In relation to the direction of the acting forces, the seams are divided into:

longitudinal;
transverse;
combined;
oblique.

According to the shape of the outer surface, the butt seams can be made normal (flat), convex or concave. Joints formed by convex seams perform better under static loads. However, excessive sagging leads to unnecessary consumption of electrode metal and therefore convex welds are uneconomical. Flat and concave seams work better under dynamic and alternating loads, since there is no abrupt transition from the base metal to the weld seam. Otherwise, a concentration of stresses is created, from which the destruction of the welded joint can begin.

According to the operating conditions of the welded unit during the operation of the product, the welded seams are divided into workers, which directly perceive the loads, and connecting (binding), intended only for fastening parts or parts of the product. Tie seams are more commonly referred to as non-working seams. In the manufacture of critical products, the bulge on the working seams is removed with electric grinders, special cutters or the flame of an argon-arc torch (smoothing).

The main types, structural elements, dimensions and designation conditions for welded joints for manual electric arc welding of carbon and low-alloy steels are regulated by GOST 5264-80.

Structural elements of welded joints. The shape of the groove and their assembly for welding is characterized by three main structural elements: the gap, the bluntness of the edges, and the bevel angle of the edge.

The type and angle of the groove determines the amount of electrode metal required to fill the groove, and hence the welding performance. X-shaped groove, in comparison with V-shaped, allows to reduce the volume of deposited metal by 1.6-1.7 times. In addition, this groove provides less deformation after welding. With X-grooves and V-grooves, the edges are blunt to properly form the seam and prevent burn-through.

The gap during assembly for welding is determined by the thickness of the metals being welded, the grade of the material, the welding method, the shape of the edge preparation, etc. ... In consumable electrode welding, the gap is usually 0-5 mm, an increase in the gap contributes to a deeper penetration of the metal.

The seam of the welded joint is characterized by the main structural elements in accordance with GOST 2601-84: width; bulge; penetration depth (for a butt weld) and a leg for a fillet weld; the thickness of the part.

The main elements of the weld are shown in Fig. 1.

Rice. 1. : a - fillet weld; b - butt seam

Technological strength of the weld. The term "Technological strength" is used to characterize the strength of a structure during its manufacture. In welded structures, technological strength is limited mainly by the strength of the welded seams. This is one of the important indicators of the weldability of steel.

Technological strength is assessed by the formation of hot and cold cracks.

Hot cracks are brittle intercrystalline fractures of the weld metal and heat-affected zone. They arise in a solid-liquid state at the final stage of primary crystallization, as well as in a solid state at high temperatures at the stage of predominant development of intergranular deformation.

The presence of a temperature-time interval of brittleness is the first reason for the formation of hot cracks. The temperature-time interval is caused by the formation of liquid and semi-liquid layers that violate the metal continuity of the weld. These interlayers are formed in the presence of low-melting, sulfur compounds (sulfides) FeS with a melting point of 1189 ° C and NiS with a melting point of 810 ° C. At the peak moment of the development of welding stresses along these liquid layers, the metal is shifted, growing into brittle cracks.

The second reason for the formation of hot cracks is high-temperature deformations. They develop due to hindered shrinkage of the weld metal, deformation of the workpieces being welded, as well as during relaxation of welding stresses in nonequilibrium welding conditions and during postweld heat treatment, structural and mechanical concentration of deformation.

Cold cracks... Cold cracks are those that form during cooling after welding at a temperature of 150 ° C or during the next few days. They have a shiny crystalline fracture without traces of high-temperature oxidation.

The main factors causing the appearance of cold cracks:

the formation of quenching structures (martensite and bainite) leads to the appearance of additional stresses due to the volumetric effect;
exposure to welding tensile stresses;
diffusible hydrogen concentration.

Hydrogen moves easily in unhardened structures. In martensite, the diffusion capacity of hydrogen decreases, it accumulates in the microvoids of martensite, transforms into a molecular form and gradually develops high pressure that promotes the formation of cold cracks. In addition, hydrogen adsorbed on the metal surface and in microvoids causes embrittlement of the metal.

Weldability- the property of a metal and a combination of metals to form, with the established welding technology, a connection that meets the requirements due to the design and operation of the product. The complexity of the concept of the weldability of materials is explained by the fact that when assessing the weldability, the relationship between welding materials, metals and product design with welding technologies must be taken into account.

There are many indicators of weldability. An indicator of the weldability of alloy steels intended, for example, for the manufacture of chemical equipment, is the ability to obtain a weld joint that provides special properties - corrosion resistance, strength at high or low temperatures.

When welding dissimilar metals, an indicator of weldability is the possibility of the formation of interatomic bonds in the joint. Homogeneous metals are joined by welding without difficulty, while some pairs of dissimilar metals do not form interatomic bonds at all in the connection, for example, copper and lead are not welded, or titanium with carbon steel.

An important indicator of the weldability of metals is the absence of hardened areas, cracks and other defects in welded joints that negatively affect the operation of the welded joint.

There is no single indicator of the weldability of metals yet.