How are welded joints and seams classified?

Types of welded joints and seams

Welding is one of the main joining methods, which is used in industry and in the private sector. This is a relatively cheap and reliable method that provides a permanent connection. Taking into account the fact that there are many varieties of metal, each of which has its own characteristics of welding, as well as different working conditions and the requirements for the connection themselves, various types of welded joints and seams are distinguished.

Types of welded joints

Weld zones

Fusion zone – occupies from 0.1 to 0.4 mm of the base metal. It contains partially melted grains. When the metal is heated in this zone, it acquires a needle-like structure. It has low strength and high fragility.

Thermal affected zone - it is divided into four sections. The first section refers to the base metal, which has been heated to temperatures above 1100 degrees Celsius. It has a coarse-grained structure. The grains in this area are approximately 12 times larger than standard grains. Due to overheating, the viscosity, ductility and other mechanical properties of the metal decrease. This is the weakest area of ​​the weld, where rupture often occurs.

The second section is the normalization zone, where the base metal is heated to 900 degrees Celsius. The grain structure here is much finer than in the previous case. This area occupies from 1 to 4 mm.

https://www.youtube.com/watch?v=qBf24cIxYuU

The third section is a zone of incomplete crystallization. Here the base metal is heated from 750 to 900 degrees Celsius. It contains both small and large grains. Due to the uneven distribution of crystals, the mechanical properties are reduced.

The fourth section is the recrystallization zone. The area warms up from 450 to 750 degrees Celsius. Here the shape of grains that were deformed by past mechanical influences is restored. The approximate width of this area is from 5 to 7 mm.

Base metal zone - starts from a section that warms up to less than 450 degrees Celsius. Here the structure is similar to the base metal, but due to heating, the steel loses its strength properties. Nitrides and oxides are released along the boundary, which weaken the bond of the grains. The metal acquires higher strength in a given location, but receives lower impact strength and ductility.

Weld zone diagram

Complete classification of welds and joints

Types of welds are divided into several categories according to various characteristics. One of them is the difference in appearance. Here they highlight:

• Concave (aka weakened);
• Convex (aka reinforced);
• Normal (aka flat).

Source: https://svarkaipayka.ru/tehnologia/drugoe/vidyi-svarnyih-soedineniy-shvov.html

Types of welding joints and seams

» Articles » Types of welding joints and seams

Welding is one of the main joining methods, which is used in industry and in the private sector. This is a relatively cheap and reliable method that provides a permanent connection. Taking into account the fact that there are many varieties of metal, each of which has its own characteristics of welding, as well as different working conditions and the requirements for the connection themselves, various types of welded joints and seams are distinguished.

Types of welded joints

Features of seams

This is the most common option, which is an ordinary connection of sheets or end surfaces. It requires a minimum amount of metal and time. It can be carried out without beveling the edges if the sheets are thin.

For thick products, it is necessary to prepare the metal for welding, where it will be necessary to bevel the edges to increase the penetration depth. This is true for thicknesses of 8 mm and above. If the part is thicker than 12 mm, then a double-sided butt joint with beveled edges is required.

Such connections are most often made in a horizontal position.

Appearance of a butt weld

T-type joints and seams are represented in the form of the letter “T”. It can be single- or double-sided, and can also connect products of different thicknesses. If a smaller part is installed perpendicularly, then the electrode must be tilted up to 60 degrees during welding.

Here you can use tacks to tilt the part and carry out a simpler version of boat welding. This reduces the likelihood of undercuts. The suture is usually applied in one pass.

Nowadays there are many devices for automatic T-welding.

Appearance of T-joint

A corner connection is one that is located at an angle of 90 degrees or another angle. Such joints are often beveled at the edges so that the seam can go to the required depth to ensure reliability. Double-sided welding makes the connection stronger.

Gusset

This method is used for welding sheets less than 1 centimeter thick. They are laid overlapping each other and boiled on both sides. Care should be taken to ensure that no moisture gets between them. Sometimes, for better bonding, such a joint is welded from the end.

Overlap welding joint

Weld geometry

Having considered the types of welds and methods of their application, it is worth paying attention to the basic geometric parameters.

Geometric parameters of a butt seam

• E – width of the formed seam;
• S – thickness of the workpiece;
• B – gap between the workpieces being welded;
• T – thickness of the resulting seam;
• H – depth of occurrence of the welded part;
• Q – size of the convex part.

Geometric parameters of fillet weld

• A is the thickness of the fillet weld, in which. Includes the magnitude of the convexity and the estimated height;
• P is the calculated height, which corresponds to a perpendicular line drawn from the place of deepest penetration to the hypotenuse of the largest right triangle inscribed in the outer part of the weld;
• Q – convexity of the deposited area;
• K – fillet weld leg is the distance from the surface of one workpiece to the corner boundary of the other.

Features of choice

All types of welded joints and seams differ markedly in their properties. Therefore, for each specific case you have to select your own set of parameters for a successful combination. First of all, you should pay attention to the spatial position. The easier the work, the better the quality of the seam.

Horizontal seams are considered the easiest to perform, therefore, craftsmen try to place the workpieces in this position. Sometimes you even have to turn the same product over several times to ensure high quality seams. "Important! It should not be forgotten that welding in one pass helps to achieve better strength than multiple passes.

Therefore, you need to find a balance between convenience and the number of passes.”

With thick workpieces, you always need to cut the edges and then treat the surface to add cleanliness. Butt options are the simplest and most preferable to work with, since they are easier to fix in order to avoid distortion of the geometry of the resulting parts. In addition to choosing the right type of seam, you also need to pay attention to the temperature regime, since then the welding zones may shift and the product will simply melt or be undercooked.

Source: https://samsvar.ru/stati/vidy-svarochnyh-soedinenij-i-shvov.html

Welded joints and seams - main types and types

To learn how to cook well, it is not enough to master holding an electric arc. It is necessary to understand what types of welded joints and seams there are. The problem for novice welders is unwelded areas and poor fracture resistance of finished parts. The reason lies in the wrong choice of the type of welded joint, as well as the wrong technique for making it.

The drawings always indicate everything a welder needs to know for a quality result. But insufficient knowledge of the designations of welded joints can also lead to defective work. Therefore, it is very important to study other articles about symbols well.

The same article discusses in detail the types of welding seams and all sorts of nuances regarding the differences and techniques for their implementation.

Types of welds by type of surface connection

Depending on the thickness of the metal, the required tightness, and the geometric shape of the parts being connected, different types of welds are used. They are divided into:

• butt;
• overlap;
• corner;
• T-bar.

Each has its own purpose, well suited to the specific needs of the finished product. The technique for making a welded joint also varies.

Joint

The most common type of welded joint is the butt. This is applicable when welding the ends of pipes, steel sheets, or other geometric shapes joined side to side. The main types of welded joints and seams include many types of end-to-end joining of parts, differing in the side of the seam and the thickness of the product. They are classified into the following subspecies:

• unilateral normal;
• one-sided with edge processing at 45º and V-shape;
• one-sided with processing one edge at 45º with a grinding machine, or using a cutter to select a semicircle equal in the amount of metal removed from the oblique cut;
• one-sided removal of the edge with a cutter on both attached parts (U-shaped groove);
• double-sided, implying edge cutting at 45º on each side (X-shaped cutting).

In the description of the work, they may be designated “C1”, or have another number after the letter, depending on the technique of execution. A regular one-sided seam is used when joining two plates no more than 4 mm thick.

If the parts have up to 8 mm of metal thickness, then the seam is applied on both sides, which is a two-sided type of welded joint.

To increase the fracture resistance coefficient, a greater depth of filling with molten metal is achieved, for which a gap of up to 2 mm is set between the two parts.

When working with products whose thickness exceeds 5 mm, and a seam is required on only one side, but high strength is expected, cutting the edges is necessary. It is carried out with a “grinder” or a file. A bevel of 45º is sufficient.

To prevent the molten metal from burning through the bottom side and causing an overflow from the back of the joined surfaces, the edges are not beveled completely, leaving a slight dullness of 2-3 mm. Similar cutting can be done on a milling machine, which takes more time and resources.

This is only used on very critical projects.

When the metal thickness exceeds 12 mm, double-sided cutting is recommended. The X-shaped processing method helps to save on the amount of metal being filled, which leads to an increase in welding speed and efficiency of the entire process.

Angular

The main types of welded joints include several fillet weld options:

• one-sided, without cutting;
• single-sided with preliminary cutting;
• double-sided, regular;
• double-sided with cutting.

A corner seam allows you to attach two sheets to each other at an angle of 90º or any other. In this case, one seam will be internal (between two plates), and the second, external (at the end of the joined plates). Welding of this type is widely used in the manufacture of:

• gazebo frames;
• visors;
• awnings;
• truck bodies.

Such a welded joint is designated “U1”, or other related numbers, depending on the nuances of the seam. If two plates have different thicknesses, then it is recommended to place the thicker one at the bottom, and place the thinner one “edge” on it. The electrode or torch is aimed primarily at the thick part. This will allow high-quality welding of parts, without the formation of undercuts and burns.

The optimal way to perform a fillet welded joint is the “boat” position, where the two surfaces, after tack welding, are positioned in such a way that it resembles the equal convergence of the hull of a floating vessel. In this case, the molten metal falls evenly on both sides, minimizing the appearance of defects.

When passing the seam from the reverse side, it is necessary to reduce the current strength so as not to melt the corner. Thanks to this, strong rounding will not appear on the outside of such welded joints.

overlap

Two plates can be welded together not end-to-end, but by slightly stretching one over the surface of the other. Such welds are used where greater tensile strength is needed. The seam must be placed on each side of the contacting surfaces. This not only increases strength, but also prevents moisture from accumulating inside the product.

In the drawings, such a seam will have the sign “H1”. There are only two types. The creation of this welded joint does not require oscillatory movements. The electrode is directed to the lower surface.

Tavrovoe

It is similar to the corner one, but the plate attached “edge” is not placed at the edge of the lower base, but at a certain distance. They are used in the installation of bases of various metal structures. If the steel thickness exceeds 4 mm, then a double-sided seam is recommended. When the dimensions of the product allow it to be turned over and installed “in a boat,” then this should be done at critical units. The remaining seams can be made in the usual position, using the recommendations for corner joints.

By spatial position

Subsequent classification of seams and joints is carried out according to the location of application in space. They are divided into:

• Lower. Often found in factories and large industries. Provides uniform distribution of molten metal, with a minimum amount of drips and sagging. To weld large products in the lower position, rotating jigs are used. The electrode or burner is always directed from top to bottom. This way you can make all types of joints according to the method of contact with each other (angle, overlap, etc.).
• Vertical. It is highly complex and requires certain skills. It is used when welding pipes (passing seams on the sides) or fastening large structures, due to the impossibility of turning them over to the lower position. Requires more welding time, less current, and an intermittent arc to prevent drips. The electrode is directed from bottom to top. Welding is also carried out.
• Horizontal. Used when connecting vertical pipes or sheets of metal. It is fraught with drips when running the seam slowly, or unwelded places when passing quickly. For convenience, the sides are set with an offset of 1 mm to form a “step” to delay the applied metal. After applying the seam, a 1 mm difference in surface protrusion is not visible.
• Ceiling. The most difficult for welders, but accessible after a specialist masters the vertical method. The seam is applied with an intermittent arc, using a lower current. Used when welding pipes when there is no possibility to turn the product. It is actively used on construction sites in the installation of ceiling channels and beams.

According to the seam shape and technology

The types of welding joints also differ in the shape of the seam itself. He can be:

• Smooth - achieved with optimal device settings and a comfortable spatial position.
• Convex - possible due to low current strength and passage through several layers. Often requires subsequent mechanical processing.
• Concave - achieved by increased current strength. It has good penetration and does not require grinding.
• Continuous - is carried out continuously and has a “lock” that prevents the appearance of fistulas.
• Intermittent - used on products made of thin sheets and with light load.

All types of seams can be performed in one pass or several. This is determined by the thickness of the parts being welded and the required strength. The first seam is called the root seam. It has narrow boundaries and is made at a lower current. Subsequent seams are multi-pass. They allow you to fill the space between the edges of the plates. They are performed at high currents and with contact with the base metal.

Knowing the main types of joints and their fundamental differences, you can correctly select the required type of seam that will satisfy the key requirements for tightness and strength in each specific case.

Source: https://svarkalegko.com/tehonology/vidy-svarnyh-soedinenij.html

Welds - classification, types of welding joints

A weld is a section where two parts are joined into a single whole due to the melting of the metal under the influence of high temperature and its further crystallization. Today, more than 100 types of connections are distinguished. They are all divided according to special parameters and divided into various groups and subgroups, and therefore there are many classifications of welds.

What is a weld seam

To begin with, let’s define the concepts of “welding seam” and “welding joint”, because some sources consider them to be one and the same thing, others separate the formulations.

The shortest definition: a weld is a permanent connection by welding.

The second option reveals the physics of the welding process as such: a weld is a section in which two or more parts are connected as a result of crystallization or deformation of a substance, or one and the other together. One way or another, it is more logical to take welding seams and joints as one and the same process.

One of the oldest and most famous standards among specialists is “GOST 5264 – 80 Manual arc welding. Welded connections." This GOST was put into effect back in 1981, it still copes with its tasks perfectly: the main types of welds, their sizes, structural elements and instructions on how to correctly lay a weld are clearly listed. An excellent example of a document that does not need adjustments over time.

What are the types of welds and connections, classification

Table 1 shows the main types of welding joints, grouped by cross-sectional shape.

No.	Welded joints and seams	Location Features	Main Application	Note
1	Butt	The connected parts and elements are in the same plane.	Welding of sheet metal structures, tanks and pipelines.	Saving consumables and welding time, joint strength. Careful preparation of the metal and selection of electrodes.
2	Corner	The connected parts and elements are located at any angle relative to each other.	Welding of containers and reservoirs.	Maximum metal thickness 3 mm.
3	Overlapping	Parallel arrangement of parts.	Welding of sheet metal structures up to 12 mm.	Large consumption of material without careful processing.
4	T-bar (letter T)	The end of one element and the side of the other are at an angle	Welding of load-bearing structures.	Careful processing of vertical sheet.
5	Face	The side surfaces of the parts are adjacent to each other	Welding of vessels without pressure	Material savings and ease of execution

By way of execution:

• Double-sided - welding from two opposite sides with removal of the root of the first side;
•  Single-layer – performed in one “pass”, with one weld bead;
•  Multilayer – the number of layers is equal to the number of “passes”. Used for large metal thicknesses.

By degree of convexity:

• Convex – reinforced;
• Concave – weakened;
•  Normal - flat.

The convexity of the seam is influenced by the welding materials used, welding modes and speed, and the width of the edges.

By position in space:

• Bottom – welding is carried out at an angle of 0° – the most optimal option, high productivity and quality;
•  Horizontal - welding is carried out at an angle from 0 to 60° require increased
•  Vertical - welding is carried out at an angle from 60 to 120° to the welder’s qualifications;
•   Ceiling - welding is carried out at an angle from 120 to 180° - the most labor-intensive, unsafe, welders undergo special training.

By length:

•  Solid - the most common;
•  Intermittent – ​​leaking structure.

Types of welded joints and seams by relative position:

•  Located in a straight line;
•  Located along a curved line;
•  Located in a circle.

In the direction of the acting force and the vector of action of external forces:

• flank - along the axis of the welded joint;
• frontal - across the axis of the welded joint;
• combined - a combination of flank and frontal;
• oblique - at a certain angle to the axis of the welded joint.

Types of welds according to the shape of the products being welded:

• on flat surfaces;
• on spherical ones.

The types of seams also depend on the thickness of the working material and the length of the joint itself:

• short – not > 25 cm, and welding is carried out using the “one pass” method;
• medium - length < 100 cm - a reverse-step welding method is used, in which the line is divided into small sections 100-300 mm long;

All extended seams are processed in a reverse-step manner, from the center to the edges.

Compare, evaluate

Of the above options, butt welding is considered the most reliable and economical. In terms of current loads, they are almost equal to whole elements that were not welded, in other words, to the base material. Naturally, such strength is achieved only with adequate quality of work.

At the same time, it must be remembered that the reliability and efficiency of the method does not mean that it is easy to implement. Requirements for edge processing, adjustment of many factors to the conditions of a specific welding, certain restrictions in application due to the shape - all this requires strict professional discipline.

Welding butt seams.

T-joints (including corner ones) are also quite popular. They are especially often used when welding massive structures.

The simplest ones to perform are overlapping joints. They do not require edge processing, and general preparation is also much simpler. Very popular in welding sheets of small thickness (thickness up to 60 mm is allowed). Simplicity does not mean efficiency: excessive consumption of deposited and base metals is a common situation for such options.

By configuration

This category of butt welds is used in manual arc welding with an electrode. This includes three types of welds - straight, curved and annular (spiral). They are produced regardless of the position of the work product. All types of seams of this classification require both butt and lap welded joints.

By length

Classification of welds by length is of two types: continuous or intermittent.

• Intermittent is a seam that is made of a certain length with a synchronous interval. It, in turn, is divided into two types - chain track and checkerboard seam. For example, double-sided intermittent joints on one side of the wall are located opposite the welded sections of the seam on the other side. These types of coupling can be either one-way or two-way. That is, the part is soldered on both sides. The distance between these welded sections is called the “welding pitch”.
• Continuous welding methods are also divided into short and long tracks, and are performed along the entire workpiece.
• The spot method of butt welds differs significantly from others, due to the fact that there is no weld pool and track. In this case, the workpieces are connected at points using an overlap weld. This method is often used for soldering thin metal or batteries.

Methods of extended seams: a) continuous b) intermittent, c) point, d) intermittent checkerboard, e) intermittent continuous (chain)

: Welding wire SV-08G2S - features and varieties

2.2 Weld designations

Conventional images of seams of welded joints. The main types, structural elements, dimensions and symbols of welded joints and seams in the drawings, as well as the shape and dimensions of the preparation of welded edges from various structural materials used in arc welding, are regulated by standards.

In the drawings of welded products, the conventional images and designations of seams given in GOST 2.312-72 are used.

The seam of a welded joint, regardless of the welding method, is conventionally depicted: visible - with a solid main line (Figure 17.a - 17.c), invisible - dashed (Figure 17.d). A visible single weld point, regardless of the welding method, is conventionally designated with a “+” sign (Figure 17. b).

From the image of a seam or a single point, draw a leader line with a one-way arrow indicating the location of the seam. It is preferable to make a leader line from the image of a visible seam.

It is allowed to draw the contours of individual passes onto the image of the cross-section of a multi-pass weld, and they must be designated in capital letters of the Russian alphabet (Figure 18.a).

Source: https://tpspribor.ru/svarka/klassifikaciya-svarnyh-shvov-i-soedineniy.html

Types of welds and joints: useful information - Welding

A novice welder who has just acquired a welding machine is always interested in what types of welding seams exist and how best to connect metal surfaces. Therefore, we consider it advisable to analyze welding joints and divide them into types. But first you need to understand the definitions of seams and joints, the differences between them.

Definitions

A weld seam is a crystallized metal that is in a molten state during operation. Regarding welding joints, they are limited areas of a metal structure containing one or more welds.

to menu

 Classification of welds and joints according to the following criteria:

• By type of welding;
• According to the shape of the metal edges prepared for work;
• According to the position of the work;
• According to the number of stitches applied;
• By configuration, as well as length;
• According to the type of welding work used;
• According to the method of holding molten metal;
• According to the material used in the work;
• By actual force;
• According to the shape of the connected structures;
• By volume of deposited metal;
• By the location of metal parts relative to each other.

By type of welding work, the following seams can be distinguished:

• Arc welding;
• Arc welding in shielding gases;
• Automatic, semi-automatic flux welding;
• Electric rivets;
• Electroslag welding;
• Soldered joints;
• Contact electric welding.

Classification by degree of convexity:

• Normal;
• Concave;
• Convex.

 Classification by spatial location:

• Lower;
• Vertical;
• Horizontal;
• Ceiling.

Types of welding seams (depending on the shape):

1. Butt – type of butt fastening seams;
2. Fillet - type of seams with corner, T or overlap fastening;
3. Slotted - a type of seam obtained as a result of complete melting of the top, in rare cases subsequent sheets, as well as the bottom sheet.

 Types of connections (depending on the nature of the mating of metal surfaces):

• Butt;
• T-bars;
• Angular;
• Overlapping;
• End face.

Butt

Considering the main types of connections, it is worth considering the most common type of connection - butt. When considering the types of connections, special attention should be paid to the butt version, since it represents the fastening of two metal elements that adjoin each other with end surfaces and are placed on the same surface or in the same plane.

Depending on the location of the seam there may be:

• One-sided;
• Double-sided.

They differ in the preparation of the place for welding, based on the thickness of the products:

• With beveled edges;
• No beveled edges.

One-sided fastenings of surfaces without beveled edges involve working with sheets whose thickness reaches 4 millimeters, while double-sided fastenings without beveled edges are performed in the process of welding sheets of metal up to 8 millimeters. Both connection options provide for a slight gap between parts with a thickness of 1-2 millimeters to ensure high-quality work.

https://www.youtube.com/watch?v=ZbnEIr5ITFc

It is advisable to bevel the edge parts of a part with one-sided fastening for diameters from 4 to 25 millimeters. It is worth noting that welding with a bevel of a V-shaped sample is very popular.

U-shaped fastening of metals is less popular among welders. It is also recommended to perform minor dulling of the edges.

If there are thicknesses of 12 millimeters or more, double-sided welding requires an X-shaped groove.

 T-bar

The T-welding method refers to such fastenings of metals in which the end surface of one metal element adjoins at an angle and is attached to the side surface of another metal element.

 Useful tips

During T-welding of thin metal with relatively thick material, it is advisable to maintain the angle of inclination of the electrode relative to the seams so that it is approximately 60 degrees.

All types of welding work can be simplified if the installation is carried out “in a boat”.

Thus, it becomes possible to work predominantly in the lower position, while the speed of work increases, and the likelihood of undercuts is significantly reduced.

When considering the types of connections of metal surfaces, it is worth knowing that the T-type version most often allows for lack of penetration and other defects.

Source: https://svarkaman.ru/metall/vidy-svarochnyh-shvov-i-soedinenij-poleznaya-informatsiya.html

Welds: classification, types of welding joints, basic geometric parameters of the seam

One way to connect parts of a material is welding. The method has found very wide application in various fields. Using this relatively cheap and at the same time reliable method, permanent connections are obtained. Taking into account the types of metals, each of which has its own welding characteristics, differences in work conditions and joint requirements, various types of welds and joints are distinguished.

The fusion zone with partially melted grains is 0.1−0.4 mm of the main metal. When the metal in this zone warms up, its structure becomes needle-like with high fragility and low strength.

The thermal zone is divided into four sections:

• I - refers to the base metal heated to a temperature exceeding 1100 °C. The structure of this area is coarse-grained, and the grains in this area are approximately 12 times larger than standard. Due to overheating, the viscosity, ductility and other mechanical properties of the metal decrease, and rupture often occurs in the weakest area of ​​the weld.
• II - section is the normalization zone, in which the main metal is heated to 900 °C. The grain structure here is much finer than in the previous case. This area occupies 1−4 mm.
• III - zone of incomplete crystallization, in which the main metal is heated to 750−900 °C. Both small and large grains are found here. Mechanical properties are reduced due to the uneven distribution of crystals.
• IV—recrystallization zone. It warms up to 450−750 °C and restores the shape of grains deformed due to past mechanical influences. Approximate width - 5−7 mm.

The main metal zone begins from a section heated to less than 450 °C. The structure here is similar to the structure of the base metal, but the steel loses its strength due to heating. Oxides and nitrides are released along the boundary, weakening the bond of the grains. The metal in this place becomes more durable, however, it receives less ductility and toughness.

Classification of welded joints and seams

Types of seams are divided into several categories depending on their characteristics. In appearance they stand out:

• Normal.
• Convex.
• Concave.

By type, welds can be single-sided or double-sided. According to the number of passes - single-pass and multi-pass. By the number of layers: single-sided and multilayer (when welding thick metals).

There are also varieties in length:

• One-sided continuous.
• Unilateral intermittent.
• Double-sided chain.
• Double-sided chess.
• Spot welds (created by resistance welding).

Types of seams according to the force vector:

• Transverse - the force is perpendicular to the seam.
• Longitudinal - force parallel to the seam.
• Oblique - force at an angle.
• Combined - signs of both transverse and longitudinal seams.

By spatial position:

• semi-ceiling;
• horizontal;
• lower;
• vertical;
• semi-horizontal;
• semi-vertical;
• ceiling;
• into the boat.

According to their functions, seams are divided into the following:

• Durable.
• Durable and dense.
• Sealed.

Width:

• Thread seams whose width practically does not exceed the diameter of the electrode.
• Widened seams are made by transverse oscillatory movements of the rod.

Butt . The most common option, representing an ordinary connection of end surfaces or sheets. Their formation requires a minimum of time and metal. They can be done without beveled edges if the sheets are thin.

For thick products, you need to prepare the metal for welding, where you will need to bevel the edges to increase the depth of welding. This is relevant for a thickness of 8 mm or more. If the thickness is more than 12 mm, double-sided butt joints and beveled edges will be required.

Most often these connections are made in a horizontal position.

Tavrovoe . T-joints are T-shaped and can be single- or double-sided. They can be used to connect products of different thicknesses.

If the smaller part is mounted perpendicular, the electrode is tilted up to 60° during the welding process. To carry out a simpler version of boat welding, use tacks. This reduces the likelihood of undercuts.

Usually the suture is applied per pass. Today, many machines for automatic T-welding are produced.

Angular . The edges of these joints (at different angles) are often bent so that the seam lies at the required depth. Double-sided welding makes the connection stronger.

Overlap . This method is used to weld sheets less than 1 cm thick. They are laid overlapping each other and boiled on both sides. There should be no moisture between them. For better bonding, the joint is sometimes welded from the end.

Seam geometry

Source: https://tokar.guru/svarka/svarnye-shvy-klassifikaciya-tipy-svarochnyh-soedineniy.html

Classification of welded joints and seams

May 12, 2016

Modern welding technology with an appropriate choice of welding materials makes it possible to obtain welded joints with mechanical properties no lower than those of the steel being welded (table below).

Materials for welding steels, temporary and design resistance of metal seams of welded joints

Wire grade for automatic or semi-automatic welding	Electrode type for manual welding	RumMPa(kgf/mm2)	Design shear resistance of fillet weld metal Rwf, MPa
submerged	in carbon dioxide
Sv-08	—	E42, E42A	410(42)	180
Sv-08A
Sv-08 GA	E46, E46A	450 (46)	200
St. SOUTH	Sv-08G2S	E50, E50A	490 (50)	215
St. UNMA
Sv-10G2	Sv-008G2S*	E60	590 (60)	240

* Only for fillet welds with leg kf=8 mm.

This is reflected in the calculated resistance values ​​of welded joints and seams. The table above shows the materials for welding steels, as well as the temporary and calculated resistances of the metal of the welded joints. It is necessary that the tensile strength of the weld metal Rwun (strength of the deposited metal) is not lower (or higher) than the tensile strength of the steel of the elements being connected, i.e. Rwun > Run.

Welds are classified according to their design, purpose, position and length.

Based on their design, seams are divided into butt and corner (roller) seams. If the force acts along a fillet weld, it is called a flank weld; if across, it is called a frontal weld. Seams can be working or connecting (structural), continuous or intermittent. According to their position in space during their execution, they can be lower, vertical, horizontal and ceiling (figure below).

The following types of welded joints are distinguished (figure below): butt, lap and butt (T- and corner). Butt joints are made using butt welds, lap joints are made using fillet welds, butt joints can be made using both fillet and butt welds.

Position of seams in space

1 - ceiling corner seam; 2 - bottom corner seam “in a boat”; 3 - horizontal butt seam; 4 - vertical fillet weld; 5,6, 7—bottom, vertical and ceiling seams

a - butt; b - overlapped flank seams; c - the same, with frontal seams; g—combined; d - end-to-end T-bar; e - the same, angular

Source: http://ros-pipe.ru/tekh_info/tekhnicheskie-stati/proektirovanie-zdaniy-i-sooruzheniy/klassifikatsiya-svarnykh-soedineniy-i-shvov/

Types of welded 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;
• type of welding used;
• method of holding molten weld metal;
• number of layers;
• material used for welding;
• the location of the parts to be welded relative to each other;
• force acting on the seam;
• volume of deposited metal;
• the shape of the welded structure;
• shape of prepared edges for welding

Depending on the type of connection, welds can be butt and corner welds. According to their location in space, the seams of welded joints are divided into bottom, 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 can be straight, circular, vertical and horizontal. According to their length, seams are divided into continuous and intermittent. Solid seams, in turn, are divided into short, medium and long.

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

• arc welding seams
• automatic and semi-automatic submerged arc welding seams
• Gas shielded arc welding seams
• electroslag welding seams
• electric riveted seams
• contact electric welding seams
• solder seams

According to the method of holding molten metal, the seams of welded joints are divided into seams made without linings and pillows; on removable and remaining steel linings: copper, flux-copper. ceramic and asbestos linings, as well as flux and gas cushions. Depending on which side the suture is applied on, there are unilateral and bilateral sutures.

According to the material used for welding, the seams of welded joints are divided into joints of carbon and alloy steels; welds connecting non-ferrous metals; bimetal connection seams; seams connecting vinyl plastic and polyethylene.

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

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

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

Welded connections are permanent connections made by welding. They can be butt, corner, lap, 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 welded surfaces may be the same or different from one another. In practice, butt joints are most often used when welding pipelines and various tanks.

Corner - a welded connection 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.

Lap welded connection involves the superposition of one element on another in the same plane with partial overlap of each other. Such connections are most often found in construction and installation work, during the construction of farms, tanks, etc.

Fig.1. Welded connections: A - butt; B - angular; B - overlap; G - T-bar

Rice. 2. Basic positions of welds in space: A - butt; B - angular; 1 - lower; 2 - horizontal; 3 - vertical; 4 - ceiling

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

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

A butt weld is a weld in a butt joint. Fillet is a weld of corner, lap and T joints.

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

According to the shape of the outer surface, welding seams 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 welds, which, moreover, work better under dynamic loads, since there is no sharp transition from the base metal to the weld.

Excessive overflow of convex welds leads to excessive consumption of electrode metal, and a sharp transition from the base metal to the weld under concentrated stresses can cause joint failure. Therefore, in the manufacture of critical structures, the convexity at the seams is removed mechanically (cutters, abrasive wheels, etc.).

Welding seams are distinguished by their position in space. These are bottom, horizontal, vertical and ceiling seams.  

Elements of the geometric shape of preparing edges for welding

The elements of the geometric shape of preparing edges for welding (Fig. 3, a) are: edge cutting angle α; the gap between the joined edges a; blunting of edges S; sheet bevel length L in the presence of a difference in metal thickness; displacement of the edges relative to each other δ.

The cutting angle of the edges is carried out when the metal thickness is more than 3 mm, since its absence (cutting the edges) can lead to lack of penetration along the cross-section of the welded joint, as well as to overheating and burnout of the metal; In the absence of cutting edges to ensure penetration, the electric welder always tries to increase the value of the welding current.

Grooving the edges allows welding to be carried out in separate layers of small cross-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 for complete 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 sheet bevel regulates a smooth transition from a thick welded part to a thinner one, eliminating stress concentrators in welded structures.

Blunting of edges is carried out to ensure stable conduction of the welding process when performing the root layer of the weld. The lack of blunting contributes to the formation of burns during welding.

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

Rice. 3. Elements of geometric shape: a - preparation of edges for welding, b - seam

Rice. 4. Examples of classification of welds

Geometry and classification of welds

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

Welds are classified according to the number of deposited 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 current forces on the seams - flank, frontal (end) (Fig. 4, c); in direction - rectilinear, circular, vertical and horizontal (Fig. 4, d).

Weld properties

The quality indicators of welded joints are influenced by many factors, which include the weldability of metals, their sensitivity to thermal influences, oxidation, etc. Therefore, to ensure that welded joints comply with certain 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, compounds that meet 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 alloying, etc. Weldability can be physical and technological.

Physical weldability is understood as the property of a material or its compositions to create a monolithic compound 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 reaction to the welding process and the ability to create a connection that satisfies the specified parameters.

Source: http://build.novosibdom.ru/node/218

All types of welded joints and types of welds according to GOST - classification

The quality of the welded joint directly depends on the type of seam selected, the electrode and the operating mode of the device. To do this, it is recommended to follow current standards, and in particular GOST 5264-80. It describes in detail the characteristics and types of welded joints and types of welds. According to GOST, special requirements are imposed for the performance of work.

Overlapping

Forming a connection by laying sheets on top of each other is relevant for metal thickness ranging from 8-12 mm. In this case, unlike butt welding, there is no need to treat the surface - just cut the workpiece evenly. It is important to correctly calculate the amount of overlap.

Features of lap welded joint:

• increased consumption of base and deposited material;
• a seam is formed between the surface of one sheet and the end of another;
• scope of application: spot, roller and resistance welding.

Before starting work, the sheets must be aligned to ensure tight pressure.

T-bar

This is a T-shaped connection in which the end of one of the sheets is welded to the plane of the other. For reliability, one or two-sided bevels can be made on the first one. With their help, the volume of deposited metal increases. Area of ​​application: arc welding of metal structures of complex shape.

Before starting work, you need to consider the following factors:

• location of the elements to be welded – top, side or bottom;
• recommended gap between joints is 2-3 mm for better connection;
• The standard seam arrangement is double-sided.
• one-sided joints are formed only if it is not possible to process the joint on both sides.

The bevel configuration is standard, the angle depends on the thickness of the metal.

Corner

They are used to connect two structural elements at a certain angle. Unlike a T-joint, the presence of a gap is unacceptable. Reliability is ensured by bevels and a large volume of directed metal.

Specifics of fillet welds:

• surface preparation is necessary - the formation of bevels of a simple or complex configuration;
• for thin-walled workpieces, one-sided connections are allowed;
• the geometry of the weld is taken into account.

This method is most often used for the manufacture of tanks or structures similar in shape.

Auxiliary welds

In addition to the main methods of connecting steel elements described above, GOST provides auxiliary ones. They can be used to form a reliable seam, taking into account the required performance qualities of the product.

Depending on the specifics of the seam, the following methods for forming a welded joint are used:

• Slotted. Necessary to achieve maximum reliability. A recess is made in one of the materials to install another sheet.
• End face. Belong to the lateral category. The sheets are overlapped, seams are made at the ends of the structure.
• With overlays. Recommended for structures with complex surface configurations. A special pad is used to ensure the connection of the two components.
• With electric rivets. The process of forming a connection is similar to traditional riveting. The difference is that the hole is filled with weld metal.

The choice of one or another weld depends on the final result - the reliability and durability of the connection.

Source: https://ismith.ru/welding/tipy-svarnyx-soedinenij-i-vidy-svarnyx-shvov-po-gost/

Types of welded joints and seams: description, technological features, requirements and GOST:

In order to learn how to cook well, it is not enough to master just holding the electric arc. In addition, you need to understand what types of welded joints and seams there are.

Beginning welders often make serious mistakes, for example, not welding the metal. And it happens that finished parts have weak fracture resistance. What is the reason? First of all, in the wrong choice of connection type, errors in technology.

Today we invite you to talk about different types of welding, types of welded joints, as well as defects!

Weld seam: definition

First, let’s define the definition of a weld seam. This is the name given to crystallized metal that was in a molten state at the time of welding.

https://www.youtube.com/watch?v=yww-vPMWEAA

The structure of the weld seam includes:

• deposited metal zone;
• mechanical fusion zone;
• heat affected zone;
• transition zone to the base metal.

Welded joint: what is it?

A welded joint is usually defined as a limited section of a structure that contains one or more welds. It is by the appearance of the connection that a specialist can determine the qualifications of the welder and understand what welding method was used. The welded connection also tells about the technological purpose of the structure.

Welds: classification

Experienced welders say: the classification of weld types can be based on a variety of factors, for example structural and strength, geometric and technological. If we consider the seams from the point of view of location, they can be divided into lower, inclined, horizontal and vertical.

The bottom seam can be called not only the simplest, but also the most durable. The fact is that the gravity of the metal makes it possible to better fill the gaps between the surfaces being connected. In addition, this type is the most economical. There are certain conditions, for example, the burner or electrode must be directed from top to bottom.

A horizontal seam is usually formed when the surfaces are perpendicular to the plane of the electrode. The consumption of fluxes and electrodes with this type increases significantly. If the seam is drawn slowly, drips may occur, and if the seam is drawn quickly, uncooked areas may occur.

It is much more difficult to make a high-quality vertical seam. Here, metal loss increases, unevenness increases (at the final stage of welding, the seam turns out to be thicker). This method requires a certain classification of the welder. It is usually used for welding pipes or when fastening large structures.

Welders consider ceiling welding to be the most difficult. How is it produced? The seam is applied with an intermittent arc. The current strength is small. This type is usually used when welding pipes that cannot be turned.

Welded joints: types and types

We propose to talk about what types of welded joints there are according to the types of joining surfaces. Depending on factors such as the thickness of the metal, the geometric shape of the parts, and the required tightness of the joint, welded joints can be divided into:

• T-bars;
• overlap;
• butt;
• corner.

All types of welded joints have their own purpose, which suits the specific needs of the finished elements. We invite you to consider these types in more detail!

Gusset

There are several corner connection options:

• one-sided - both with and without preliminary cutting;
• double-sided - regular and with cutting.

Using this connection, you can fasten two elements together at any angle. In this case, the first seam will be internal, and the second - external. This type is ideal for welding various canopies and canopies, truck bodies and gazebo frames.

If you need to connect two plates of different thicknesses, this type of welded joint according to GOST must be performed as follows: the thicker plate should be placed at the bottom, and the thinner should be placed on it edgewise. In this case, the electrode or burner should be directed at the thick part - this way there will be no burns or undercuts on the part.

Lap joint

Two plates can be welded not only end-to-end, but also overlapping - by slightly pulling one onto the surface of the second. Experts recommend using this type of welded joint where greater tensile strength is required. The seam must be placed on each side - this will not only increase strength, but also prevent the accumulation of moisture inside the finished product.

T-joint

This type is similar to a corner connection, but there are differences - the plate, attached with an edge, should not be placed at the edge of the lower base, but at a short distance.

Classification by technology and seam shape

Welders distinguish between types of welded joints based on the type of welds. The seam can be:

1. Smooth. It is achieved with optimal settings of the welding machine and with its comfortable position.
2. Convex. Such a seam can be obtained with low current and passing through several layers. A convex seam requires machining.
3. Concave. Such a seam can only be obtained with increased current strength. This type of weld has excellent penetration and does not require grinding.
4. Solid. To make a high-quality continuous seam, you need to do it continuously. This will prevent the occurrence of fistulas.
5. Intermittent. This seam should be used for products made from thin sheets.

A welder who is familiar with the main types of joints and their fundamental differences can correctly select the type of weld that can satisfy the basic requirements for strength and tightness.

Defects in welded joints: types, description, causes

Welded joints can have various effects that affect strength and sealing. It is customary to divide all types of defects into three categories:

• internal (these include lack of penetration, porosity and foreign inclusions);
• external (including cracks, undercuts, craters, sagging);
• through (here you can highlight burns and cracks).

Let's talk in more detail about each type of defect.

Cracks

This type of defect is considered the most dangerous; it can lead to rapid destruction of welded structures. Cracks are distinguished by their size (there are macro- and microcracks) and by the time of appearance (during the process of welding parts or after). The reason for the appearance of cracks is non-compliance with welding technology, incorrect choice of materials for welding, or too rapid cooling of the structure.

You can fix a crack as follows: drill out its beginning and end, remove the seam and weld it.

Undercuts

Undercuts are the depressions between the seam and the metal. The seam becomes weak due to this defect. The reason for the appearance of undercuts is an increased current value. An undercut usually occurs on horizontal seams. This defect can be eliminated by surfacing a thin weld along the undercut line.

Surges

Such a defect can appear when molten metal flows onto the base metal without forming a homogeneous compound. The reasons for the appearance of sagging are simple - the base metal is not heated, the welder uses an excessive amount of filler material. The defect can be eliminated by cutting, making sure to check for lack of penetration.

Burns

Burn-throughs are defects that manifest themselves in through penetration and leakage of liquid metal. In this case, on the other side, as a rule, a sag appears. The cause of burn-throughs is high welding current, slow movement of the electrode, insufficient thickness of the lining, or too large a gap between the edges of the metal being welded. You can fix a burn-through: just clean and weld the defect area.

Lack of penetration

Lack of penetration refers to local lack of fusion of the deposited metal with the base metal. Lack of penetration can also be called non-filling of the seam section. This type of defect reduces the strength of the seam and causes destruction of the finished structure. The reason lies in the low welding current, the presence of slag or rust on the parts being welded. To correct the error, you need to cut out the lack of fusion and weld the parts.

Craters

The depressions, called craters, are usually caused by a broken welding arc. If such a defect appears, it is necessary to cut it down to the base metal and carefully weld it.

Fistulas

This is the common name for cavities that reduce the strength of the seam. It is because of fistulas that cracks can form. Cutting out the defect and welding will correct the situation.

Porosity

What is porosity? These are cavities that are filled with gases. The reason for their appearance is intense gas formation inside the metal. Pore ​​sizes can be either microscopic or reaching several millimeters. To avoid porosity, the metal should be cleaned of dirt and foreign substances. It is necessary that the electrode is not wet. If a mistake has already been made, the porous zone should be cut out to the base metal and welded, following the technology.

Overheating and burnout

These defects appear as a result of high welding current or insufficient welding speed. Because of this, the finished product becomes very fragile. Burnt metal can only be cut out, and the metals can be welded again.

Welding control

Now let's look at the types of inspection of welded joints. The following methods exist:

• visual inspection;
• chemical analysis;
• transillumination with gamma rays or x-rays;
• metallographic analysis;
• ultrasonic or magnetic flaw detection;
• mechanical tests.

There is a very important rule - for reliable control, it is imperative to clean the joint from slag, scale and welding spatter!

Source: https://www.syl.ru/article/364740/vidyi-svarnyih-soedineniy-i-shvov-opisanie-tehnologicheskie-osobennosti-trebovaniya-i-gost