What is called a weld joint and a weld seam?

Welded butt joints: features, types and technology

In industry and in everyday life, metal parts are connected into a single structure using welding. This method is considered the most reliable and quite cheap. Relatively not very complex equipment (welding machine, electrodes, protective equipment) allows you to create and repair many metal structures in a short time and with fairly reliable quality.

To create a durable metal product, a novice welder needs to thoroughly know the features and types of butt welded joints, as well as the technology of the work being performed.

Definition of a weld joint

Welding of metals is the joining of metals by melting the edges of the product and their subsequent crystallization during the cooling process. The welding process is accompanied by complex physical and chemical processes. These numerous factors are what the welder must take into account when performing the work. Moreover, all these physical and chemical processes are interconnected in time and space.

During welding, several specific zones arise that characterize the welded joint:

• fusion site (welding pool), where molten grains of metal and electrode are located at the boundary of the base metal and the weld;
• a weld that is formed after cooling and crystallization of the weld pool;
• the thermally affected zone is determined by a section of metal that has not melted, but has changed its composition and structure as a result of heating;
• a base metal that can be welded without changing its properties.

Types of welded joints

The connection of two metal parts is classified according to their relative position relative to each other. The type of connection during welding work is chosen by the welder, taking into account the characteristic features of the metal and the ability to achieve a high-quality result.

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

Depending on the placement of products in space, connections are divided into the following types:

• butt joint;
• gusset;
• tee fastening;
• lap joint;
• end view.

Butt welding

The most common type of welding is the butt joint. With this type of welding, the two parts being joined are located in the same plane, so the surface of one element is a continuation of the other.

During butt welding, the elements are adjacent to each other with their end surfaces. The ends of the welded edges can be beveled or without bevel.

Moreover, without a bevel, the highest quality welding seams are obtained on metal sheets up to 4 mm thick. A double-sided butt welded joint without bevel of the metal ends makes it possible to achieve good results with parts up to 8 mm thick.

To improve the quality of the connection, it is necessary to make a gap of up to two millimeters between the plates.

It is advisable to carry out one-sided welding of parts with a thickness of 4 to 25 millimeters with preliminary bevel of the edges. The V-shaped bevel of the end surface is more popular among welders. Sheets with a thickness of 12 mm or more are recommended to be welded using a double-sided method with an X-shaped groove.

Classification by seam position

The quality of the weld depends on the position of the product in space. There are four main ways to make butt weld joints:

1. The bottom joining method is used when the welder is located on top, in relation to the surfaces of the product being welded. This method is the most convenient, since the molten metal does not flow down or to the sides, but falls directly into the crater. In this case, slag and gas are removed from the weld pool without obstruction and freely come to the surface.
2. Horizontal seams are made on vertically located plates, while the electrode is guided from left to right or from right to left. High-quality execution of a horizontal weld involves strict control of the molten metal, preventing it from flowing down, therefore it is necessary to correctly select the speed of the electrode and the current strength.
3. The vertical method is used on parts located vertically, with the seam of the butt joint being made from top to bottom or vice versa. The difficulty of such welding is that the molten metal flows down, ruining the appearance and quality of the joint. Typically, welders try to avoid working in this position. Only experienced craftsmen resort to this method, relying on their theoretical and practical knowledge.
4. With the ceiling method, the parts to be welded are located above the welder’s head. When using this method, you must strictly follow the technological process and safety rules, since the molten metal drips down.

Butt joints can be classified according to the type of impact of welding equipment. It is the use of appropriate devices and devices that makes it possible to obtain the following types of seams:

• Manual electric arc welding helps create a weld using a special electrode and allows you to obtain reliable fastening of metal parts with a thickness of 0.1 to 100 mm.
• Arc welding using inert gas allows you to obtain durable and aesthetic seams, since all welding processes take place under the protection of a gas cloud.
• Automatic welding carries out butt joints of metal in the independent mode of the inverter, here the welder controls the process after setting up the equipment.
• In gas welding, the formation of a weld occurs due to the high temperature of the burning gas mixture.
• Using a soldering iron it is possible to create soldered seams.

Weld profile

If you cut a butt joint, it is easy to determine the nature of the seam by its appearance:

• The concave weld is weakened, therefore it is mainly used for welding thin elements, for structures with a small dynamic load.
• Convex seams are considered reinforced, therefore they are widely used in structures with large static loads; the creation of such a seam requires increased consumption of electrodes.

• Normal welds are used for dynamic loads, in which case there is no special difference between the base metal and the height of the seam.

Types of seams by length

Another significant factor in obtaining a high-quality connection between two metals is the length of the weld. The calculation of butt joints takes into account the type and length of the weld.

According to the length, the joints of the connection are classified as continuous or intermittent:

1. Continuous welds do not have gaps free from welding along the entire length of the connection between two metal surfaces. This type of welding allows you to obtain the highest quality and durable connection of any structures. The disadvantage of continuous electrode guidance is the high consumption of material and slow performance of work.

2. The intermittent method is used when it is not necessary to create a particularly strong connection. Such seams are most often made of a certain length with strict synchronous intervals. Welding using the intermittent method can be carried out in a staggered pattern or in a chain path.

Welding safety precautions

The welding process is accompanied by a number of factors that can affect human health safety. The main damaging factors are considered to be the presence of radiation that affects vision, the harmful effects of the gas released, as well as exposure to molten metal.

Therefore, in all modern enterprises, special attention is paid to welder protective clothing:

• canvas suit;
• boots or boots with closed laces;
• welder's mask or safety glasses;
• a respirator that protects the respiratory system;
• canvas mittens.

All items must be clean, free of oily liquid stains.

To acquire welding skills, it is better for a novice welder to start with simple products, since the reliability and strength of any metal structure depends on a high-quality connection. Correct execution of the welding process is the main guarantee of quality work.

Source: https://FB.ru/article/410069/svarnyie-styikovyie-soedineniya-osobennosti-vidyi-i-tehnologiya

Butt welded joints: how they differ from lap joints, manual arc welding technology in the lower and vertical positions, details, video

A butt welding connection is the adjoining of two parts with their end surfaces to each other, lying on the same plane. This connection is simple and reliable, and is recommended in structures that are exposed to alternating voltages.

Where is it used?

A butt joint is used when metal thickening is excluded or not suitable , it provides a beautiful appearance without protruding edges. Butt joints are used in the aerospace and automotive industries. It is used to form a permanent connection between parts of various metal structures in the case when the surfaces of the parts lie in the same plane and are adjacent to each other at their ends .

Parts of various pipelines, shells of various containers, cylinders, tanks, sheet structures, channels, angles and other shaped profiles are butt welded.

Advantages

Pipe welding is usually done using a butt joint

For butt connection

• less electrode metal is used,
• it is not difficult to control the process, the designs are reliable,
• The welding technique is simpler than the fillet weld technique,
• butt joints ensure the flatness of the surface of the structure,
• provide connections between parts of different thicknesses,
• It is possible to weld thick metal with a one-sided seam.

Flaws

Butt joint

• does not provide additional rigidity compared to overlap,
• Significant surface deformations may also occur after welding (especially when welding thin metal).

How is it different from overlap

Welded lap joints are the fusion of different elements of a part located in parallel, partially overlapping each other. Used when butt jointing is not possible. An overlap connection is not recommended if the structure is subject to vibration; the steel thickness should be no more than 10-12 mm.

With butt it is important to take into account the accuracy of assembly , while with overlap assembly is much simpler and there is no need to cut the edges.

The disadvantage of an overlap joint will be the greater consumption of base metal, since one part covers another, corrosion of the metal may occur from moisture penetration between the parts, and it will not be easy to identify defects.

In butt welding there is no overlap (overlapping) of parts; different welding techniques are used when welding overlap joints is performed using a fillet weld . In lap joints there is no need to cut the edges; there are also a large number of types of butt joints according to GOST.

Cutting edges for welding

butt joint without beveled edges

Important! If you weld without beveled edges and the metal thickness is more than 2 mm, you need to set a gap between the parts being welded!

The quality of the seam and the product depends on the choice of bevel of the edges. For each welding method, different edge preparations are selected.

For your information! Without cutting, the process will be much more economical, but cutting the edges is necessary for complete penetration in the cross-section, which makes the quality higher.

with V-shaped edges

with X-shaped bevel edges

with curved edges

The cutting can be done with a chisel, in this case the edges will not be even, an excellent option would be a grinder, a milling machine, the best option would be to use an edge cutter (beveler). also need to control the cleanliness of the bevels in order to get a high-quality seam without defects . For butt joints, all types of edge cutting are used depending on the thickness of the metal and the nature of the seam (one-sided or double-sided seam).

There is a designation for cutting edges: U-V-K-X-shaped.
The X-shaped groove of the edges, compared to the V-shaped one, allows you to reduce the volume of deposited metal; the X-shaped groove requires one seam on each side, while the V-shaped one requires a one-sided seam. The shape of the edges depends on the welding method, the material being welded, and the thickness of the elements being welded. [ads-pc-3][ads-mob-3]

How to cook

Before starting welding, technological preparation is carried out. Parts should be marked, cut, surfaces should be cleaned of dirt and rust and dried if moisture is present.

The two parts to be welded must lie on a flat surface and have a gap of 2-3 mm between them; we ignite the electrode with a blow or “strike” like a match, and perform two tacks to avoid deformation of the joint being welded.

The video below shows what welding can lead to if you don’t use tacks (what you need to know about tacks here).

with lining (removable or remaining)

You can move the electrode towards yourself, away from you, from right to left and from left to right. Depending on the thickness of the metal and the recommended spatial position of the electrode, the method of moving the electrode for better welding is selected, and the electrode is also held at an angle of 45 degrees during operation.

After completing the seam, the slag is removed and the surface is cleaned. To avoid burns, use linings, with them the work is more confident, you can increase the current and not cook on the other side of the seam (see photo on the left).

Welding in the down position

The parts are cleaned; for thin metal, edge cutting is not performed; the gap between the parts to be welded is 1-3 mm. The assembly is carried out, the tacks are installed (after the tacks are cleaned), then welding is carried out on the back side of the tacks.

The thickness of the roller should not exceed 9 mm and the height 1.5 mm. We carry out welding from left to right, perform circular oscillatory movements counterclockwise, also weld the second side, on the second side you can increase the current, after welding we clean the surfaces.

butt joint with flange (for thin metal)

During the welding process, the electrode makes 2-3 movements.

1. The electrode is lowered down as it melts, ensuring a stable burning of the welding arc.
2. The electrode is moved at a uniform speed, tilting it at an angle of 15-30 degrees from the vertical. In the other plane, the electrode is perpendicular to the joint surface.
3. If it is necessary to obtain a weld of increased width, various oscillatory movements are used.

A short video, without much explanation, but quick, for the impatient.

Source: https://WeldElec.com/svarka/nauchitsya/soedineniya/stykovye/

How to properly weld a vertical seam using electric welding or an arc inverter for beginners, how to weld with a welding electrode

06Dec

articles

In the article we will talk about how to properly weld a vertical welding seam with an electrode and electric arc welding, what problems are encountered in the work and how to deal with them.

Vertical welding

Welders are often faced with a situation where a welded joint needs to be carried out in different planes; this happens with ceiling and side structures. Sometimes these are parts located at an angle, in other cases they are straight, but have inconvenient access - on the ceiling. The main difficulty is that the force of attraction acts on the molten metal, so it can result in an unsightly, and most importantly, non-functional leak.

General definitions

There are several types of seams depending on where they are located. Towards:

• vertical;
• horizontal.

By plane:

The simplest one runs along the horizon and is located below, on the desktop. Then it is very easy to monitor the weld pool being formed, and the deposition itself is laid down neatly and consistently, regardless of how the electrode moves.

Types of connections

The welder can apply a seam on one side or on both sides; in the latter case, this increases reliability, but can sometimes be difficult. Then the forces are compensated, and no fractures or deformations occur. There are also 4 classic types of welding depending on the location of the two parts of the product:

• end-to-end - the workpieces are located with two edges close to each other, without gaps;
• T-shaped - an inverted letter “T”, that is, a vertical one is applied to a horizontal plane;
• overlap - one metal die is overlapped with another;
• corner - the most difficult, because you need to achieve the correct angle when connecting.

Let's tell you in more detail. Or you can watch this video tutorial:

Butt-butt

Mainly used when working with sheets or pipes. The gap should be no more than 1-2 mm (molten metal will be located here). The elements themselves must be rigidly fixed. Sometimes it is necessary to pre-margin the edges (bevel them to create a recess for fusing) - with a steel thickness of more than 4 mm.

Please note that the deeper the cavity, the better the connection, but the process itself uses more electrodes (filler wire on a semi-automatic machine) and takes longer. If the width of the workpiece is very large, you will need to make several successive passes.

A multi-layer weld can be filled with layers or spot welds, as in this schematic illustration:

overlap

Suitable for sheets no more than 8 mm thick. They are placed one on top of the other and boiled on both sides; otherwise, a gap is formed in which a source of corrosion can occur.

The main feature here is the angle of inclination of the electrode. It should be 15-45 degrees from the top surface. If it is less, then the seam will be on the bottom die, more - on the top. In any case, there will be no reliable contact.

How to weld a vertical seam in a T-joint or corner joint

The technology in both cases remains the same, visually the products resemble the letter “T” in the first situation, and “G” in the second. Sometimes pre-processing is required, depending on how thick the pieces are. Let's look at the table:

Metal thickness	Number of passes	Edge processing
Up to 4 mm	1, one side	Not required
From 4 to 8 mm	2, double-sided	Not required
From 8 to 12 mm	1, cutting side	Pre-bevel at 45 degrees
From 12 mm	2, double-sided	Two bevels of the vertical plane

With a corner connection, welding can be carried out from the inside or outside; this determines which edge part the excess will be removed from. You can also do a double pass. For clarity, let's look at the diagram:

If the corner is welded inside, then it is important to position the electrode in the direction of the bisector, that is, exactly in the middle. Welders call this method “in a boat” because two workpieces form a kind of watercraft. But if you are working with steel sheets of ambiguous thickness, then a more direct impact should be on the thick metal, as in the image:

Welding fillet welds

Several difficulties arise during the work. The first is that molten metal flows down from a vertically positioned workpiece. The second appears in cases where you have used an unsuitable electrode for the job, one that is too large in diameter. Its tip simply does not fit in the corner.

It's easy to avoid this. Initially, when igniting the electric arc and filling the entire space, rotational movements should be made. The first touch is to the vertical and at a large angle, then the conductor should be gradually aligned at 45 degrees and higher, and the tip should be lowered to the horizontal, then repeated in a circle. The technique is perfectly depicted in the figure:

Position in space

Everything here is very simple in theory, but not easy in execution. The easiest way to imagine it is this: walk your eyes around the room, how many straight lines there are, so many possibilities for connection for the welder. Like in this picture:

How to properly weld a vertical seam using electric welding

To overcome the force of gravity, you must adhere to two basic principles:

• Crystallization of the metal should occur faster than during normal operation. This can be achieved if the amount of molten alloy is less. That is, you need to maintain a minimum length of the electric arc - move the electrode with intermittent movements, similar to tapping.
• The best movement is from bottom to top. So, a hardened mass will form below, which will prevent the metal composition from flowing down.

But the second principle cannot always be implemented. There are situations when you need to change direction. Below we will tell you what needs to be done for this.

How to weld a vertical seam using arc welding using the bottom-up technique

First, you should make short, up to 2 cm, clamps along the entire line. They connect the two sheets and prevent further movement or deformation due to heat.

The angle of inclination of the conductor should not be less than 45 degrees, more is permissible up to 90. The electrode itself should be directed upward. Work begins at the lowest point. Movement speed is low. It is necessary to monitor the bathroom so that it is not too large.

If the welder is connecting a structure with walls exceeding 4 mm, then it is permissible to make transverse movements, for example, in a herringbone pattern. They increase strength. Let's look at the options in the image:

How to properly weld a vertical seam using top-down technology using electric welding

To achieve good control over the movement of the melt, the angle of the electrode should be changed. First it should be at 90 degrees. When the first fusion occurs, you need to move the conductor closer - 70-75.

The rest of the tricks remain the same. Experienced welders believe that although it is more difficult to weld in this direction, the result is much better in strength and appearance.

Horizontal connection

This is a simpler science, but the force of attraction continues to work if the welded surfaces themselves are vertical. From right to left or vice versa - depends on the specialist’s technique and his convenience.

It is considered normal to constantly maintain the arc, but if you cannot control the weld pool, you can extinguish and re-ignite the arc several times.

The width of the penetration depends on the selected pattern (See above), and the absence of drips depends on the current strength. It should be minimal, but sufficient for work. Selected by experience. The second option is to increase the speed of the conductor to reduce the amount of molten metal.

How to properly cook a ceiling vertical

This is the most difficult task, the following recommendations will help you complete it:

• The position of the electrode is 90 degrees to the surface.
• The arc is short.
• The speed of movement is constant, high.
• The pattern is circular to make the welded area wider.

It is important to use protective equipment.

Conductor position control

There are three possible electrode locations:

Angle forward	Horizontal, vertical, ceiling structures, pipes, thin-walled workpieces, as a wide melt and shallow depth are obtained
Back	Corner joints and thick samples that require deep welding
Straight	Hard to reach places

Parameters for vertical welding seam

There are standard recommended values, but we advise you to experimentally test the set mode.

Electrode diameter, mm Welding current at seam position, A

lower	vertical	ceiling
3	70 — 100	70 — 80
4	120 — 150	100 — 120	100
5	150 — 180	130 — 150	—

Instructions for a beginner welder

We recommend that newcomers check their workplace for compliance with safety regulations:

• Robust clothing with covered arms and legs. Shoes are made of hard leather. Be sure to have special glasses or a mask.
• The device must be in good working order. Get to know it, check out the different modes.
• Prepare the space: remove flammable items.

Cleaning seams

First, use a hammer and chisel to knock off the splashes - scale. If a convex connection is not suitable for you, and you are confident in the depth and strength of the weld, then you can use special metal grinding.

Let's look at the video of how experienced welders do it:

Defects

We'll tell you what anyone can encounter if they do the work incorrectly.

Lack of penetration

Cavities of air or unjoined steel remain in the joint.

The result is a weak connection. The reason is low current or too fast movement of the electrode.

Undercut

Essentially, this is a groove that is formed like this - the weld pool is very wide, so the workpiece is heated over a long distance. A drop of melt goes down, and a cavity forms in place. To prevent this, the electric arc should be reduced. Very typical for verticals or corners.

Burn-through

Every beginner who wants to increase the supply of electricity faces this. A cavity is formed. Here we can advise one thing - you need to move the electrode smoothly, do not leave it in one place for a long time. More details about defects and causes in the video:

Pores and sagging

Essentially, these are irregularities - in one place crystallization was faster, and in another - slower. This is usually due to incorrectly selected electrodes (simply of poor quality) or a draft. It looks like this:

Cracks

They mean that the connection is not strong enough for the loads applied. The procedure must be repeated.

In the article we told you how to properly weld a vertical seam using an inverter or electric arc welding for beginners. To reinforce the material, watch the video:

Source: http://rocta.ru/info/kak-varit-vertikalnyj-shov-ehlektrosvarkoj-pravilnaya-svarka-invertorom-dlya-nachinayushchih/

Butt welded joint

What kind of welding is called butt welding? The answer to this question lies in the very phrase joint, seam and welding.

A butt welded joint is the most common method of welding two metal parts, elements or structures that are adjacent to each other at their end surfaces.

The welding seam can be either single-sided or double-sided, with or without a remaining backing, with a lock seam, etc. There are many options for butt welding and each of them is used in one or another production process.

The ends of the parts must be specially prepared to perform high-quality welding work. The type of edge processing depends on the thickness of the metal, the equipment used, the characteristics of the technological process and other factors.

Butt welded joints are made in accordance with GOST 5264-80, which regulates all the features of the technology. This document provides 32 types of such connections, designated by the letter C with a numerical code.

For example, C2 is a single-sided butt seam without any bevel of the edge surfaces.

Start of butt welding

Application area

This type of welded joints is used everywhere. Laying various metal pipelines is impossible without butt welding of individual pipes. Car body parts, any rental products, various complex products in the engineering industry are combined into one whole using this technology.

Advantages and disadvantages

Butt weld joints have the following number of advantages over other methods of assembling metal elements into one structure.

1. This welding technology is not critical to the thickness of the parts being welded. The thickness can vary from fractions to hundreds of millimeters. This criterion does not depend on the welding method and is determined only by the possibility of butt joining the material.
2. A butt weld requires less filler materials and energy resources, therefore reducing the cost of the connection.
3. Unlike other types of joining parts, welding practically does not increase the overall weight of the structure, the seam is smooth and sealed, and quality control of the connecting weld is simplified.

Source: https://svarkaipayka.ru/tehnologia/drugoe/styikovoe-svarnoe-soedinenie.html

Weld seam or weld seam how to write correctly

Welded metal joints are among the main methods of fastening structures used in everyday life and production. This is a very reliable method of obtaining a single design, which is also relatively cheap.

Bonds of this type are formed by melting the metal in the joint area and then crystallizing it as it cools. Their quality depends on the correct choice of operating mode of the electric welding machine, electrode, and seam penetration. This is regulated by current regulations and standards. They indicate all types of welds, as well as types of joints and their characteristics.

Numerous metals have their own welding characteristics, different work conditions, and requirements for fastening. For them, appropriate types of electric welded connections are used. When welding metal elements, the main types of electric welding fasteners are used, which are discussed below.

Classification

Welding joints are divided into several varieties, depending on their characteristics. The classification of welds covers the entire range of their uses. According to external parameters they are:

• convex type (with reinforcement);
• concave (weakened design);
• flat type (normal).

According to the type of execution, they are found in one-sided, as well as double-sided, according to the number of passes with the electrode: single-pass, double-pass. In addition, there are single-layer and double-layer welding methods.

According to their length, suture fastenings are:

• unilateral with intermittent pitch;
• solid one-sided;
• spot (with contact electric welding);
• chain double-sided;
• double-sided checkerboard pattern.

Separation by spatial location:

• horizontal, lower;
• vertical, ceiling;
• into a boat;
• semi-horizontal design;
• semi-ceiling type;
• semi-vertical.

According to the force vector:

• longitudinal (flank) – the force has a vector parallel to the penetration;
• transverse - the force acts perpendicularly;
• combined - a type of frontal, as well as flank;
• oblique - the impact occurs at an angle.

According to their purpose and function, electric welding penetrations can be durable, as well as durable and tight, hermetically sealed. Based on their width, they are distinguished into thread type, which does not exceed the diameter of the electric welding electrode rod, and widened, performed using oscillatory movements when welding in the transverse direction.

To simplify the understanding of the classification and application of certain varieties, a special table has been compiled.

All types of seams have strict designations according to GOST. The drawings use special icons that contain complete information about the type of fastening and its method of execution. For those who are thinking of seriously engaging in welding work at a professional level, they should additionally study the drawing symbols of welded fasteners.

Types of welds

Depending on the material used, thickness, and design features, different types of welds are used. To do this, you need to undergo the necessary theoretical training. This will allow you to better understand the specifics of welding parts and avoid defects in work. Novice welders often do not sufficiently weld the joint areas, which affects the weak mechanical resistance of the joints.

By choosing the right operating modes and types of welding, you can obtain welding seams of sufficient strength and quality. Welder training consists not only of practical training, but also of theoretical training with the study of requirements, norms and rules, as well as including the types of welding joints and equipment used.

Knowledge of the principles of using certain electric welding fasteners, the techniques for producing them, the joints will be very strong and durable.

Butt

This connection option is the most used among other types of welding seams. This butt welding is used on end sections, pipes or sheet metal structures. To obtain it, a minimum amount of time, material and effort is spent. These butt joints have some seam features. On thin sheet metal, welding is carried out without bevel of edges.

Products with large thickness of joint sections require preliminary preparation of joints, which consists of bevelling them to increase the depth of welding penetration. This is necessary when the thickness of metal products is over 8 mm and up to 12 mm. Thicker sections must be joined by double-sided welding with preliminary bevel of the edges. Butt welding is most often performed on products in a horizontal plane.

T-bar

These types of electric welding connections are made like a regular letter “T”. They connect objects of the same or different thickness, which determines the width of the weld seam. In addition, these types are used single- or double-sided, which is influenced by the characteristics of the fastening.

When working with metal elements of varying thickness, the electrode is held in an inclined position at an angle of about 60 degrees. The welding process can be greatly simplified by using tacks, as well as boat welding. This method significantly reduces the occurrence of undercuts. The T-weld is applied in one welding pass.

In addition to manual arc welding, automatic electric welding machines are widely used for this type.

Overlapping

This method is used for welding sheet metal with a thickness of up to 12 mm. The areas to be joined are overlapped and welded along the joints on both sides. Do not allow moisture to enter the interior of the structure being welded. To strengthen the bond, full welding is performed around the perimeter.

With this welding, the formation of a connecting joint occurs between the end of one product and the surface of another. With this type of welding seams and connections, the consumption of materials increases, which must be taken into account in advance. Before starting work, you should align the sheet structures and ensure that they are pressed well together.

Corner

These connections include fastenings of elements made at a certain angle to each other. They are characterized by the use of preliminary bevels to ensure the best weld penetration.

This will increase the depth of the welding joint, which will increase the reliability of the structure. To enhance strength, double-sided welding of metal products is used, while gaps in the joined edges are not allowed.

These types of electric welds are characterized by increased use of the volume of deposited metal.

Ceiling

Welding with a ceiling seam, the seam of which is located above the welder, is one of the most difficult types of electric welding work. It is applied by intermittent welding at a low electric current.

Vertical and ceiling connections are very difficult, so not all welders can perform them with sufficient quality. They are used in places where it is not possible to change the position of the structures being welded. These are pipes, various metal structures, as well as ceiling beams and channels at construction sites.

The specifics of making ceiling seams, the video of which will explain the nuances, can be mastered through constant practice.

Weld geometry

Having studied numerous types and methods of obtaining joints by welding, it is necessary to familiarize yourself with the geometry of the joints, which photos of welding seams will help with.

The main parameters of a seam joint include its width - e, welding thickness - c, convexity - q, gap - b, welding depth - h, and the thickness of the material being welded - S.

For corner joints, the following designations are used: convexity - q, thickness - a, leg - k and design height - p.

Various methods of applying welds, their numerous types, as well as the parameters of the prepared edges affect the volume of use of the deposited and base metals. Its quantity may differ markedly when any calculated values ​​change.

Types of welding joints are characterized by a shape coefficient, which is calculated by the ratio of the width to the thickness of the seam joint. For butt fastenings, this parameter is in the range of 1.2-2 (limit values ​​0.8-4). The convexity coefficient is calculated by the ratio of width to convexity, the value of which should be from 0.8 to 4.

Welding metal materials at an angle relative to each other requires precise adherence to the geometry of the seam. The reliability of the connection, as well as its durability of use, directly depends on the quality of welding and compliance with the required parameters.

Types of control

The further operation of the structure depends on the high-quality execution of electric welded fastening. Various defects significantly reduce the strength and reduce the period of use of the product.

To prevent defects, as well as to prevent emergency situations, various types of control of welds are used.

These include an external inspection, which can visually determine violations, their types, as well as the use of special equipment to determine hidden defects in welds.

Control methods are divided into non-destructible and destructible. When using the first method, the strength of the welded joint is determined without changing its appearance or parameters. Destructible methods are used for mass production of structures using the same type of electric welding work. This makes it possible to accurately detect internal defects in welding joints.

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GOST 5264-80. Manual arc welding. Welded connections. Main types, structural elements and dimensions

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Exothermic (thermite) welding. This is the welding of parts with molten metal formed during a chemical reaction accompanied by high temperature (a large amount of heat). The main component of this type of welding is the thermite mixture.

This method makes it possible to create bonds at the molecular level for different materials without any external sources of energy or heat: copper - copper; copper – galvanized steel; copper – “black” steel; copper – copper-plated steel; copper – stainless steel; copper - bronze; copper - brass; and even steel - steel.

Forge welding. The first type of welding in history. The joining of materials is carried out due to the formation of interatomic bonds during plastic deformation with a tool (forging hammer). Currently, it is practically not used in industry, but is supported by handicrafts and small-scale production, mainly for the manufacture of fashionable forged products - gates, fences, interior items, etc.

Contact welding. During resistance welding, two sequential processes occur: heating of the welded products to a plastic state and their joint plastic deformation. The main varieties of this method are spot welding and seam welding. Resistance butt welding, continuous flash butt welding and projection welding are also used in industry.

When spot welding, parts are clamped in the electrodes of a welding machine or in special welding pliers (Fig. 4). After this, a large current begins to flow between the electrodes, which heats the metal of the parts at the point of their contact to melting temperatures. Then the current is turned off and “forging” is carried out by increasing the compression force of the electrodes. The metal crystallizes when the electrodes are compressed, and a welded joint is formed.

Rice. 4. Resistance spot welding:

1 – parts to be welded; 2 – electrodes; 3 – compression force; 4 – weld pool

Another subtype of spot welding is seam welding. The product is fed along the seam here by rotating rollers. Welding current is supplied through the rollers in short pulses (fractions of seconds) with short pauses, forming welding points that overlap each other's edges. This creates seam continuity. This method is used for welding gas tanks, fire extinguishers, flasks, etc.

Electric arc welding and gas welding and cutting are most often used in everyday life and small-scale production. They will be discussed in more detail in this book. But first you need to decide on the specific terminology used to describe welding processes.

Welding terminology

A metal structure made by welding from individual parts is called welded, and part of such a structure is called a welded assembly. GOST 2601–84 establishes a number of terms and definitions for welded joints and seams.

The base metal is the metal of the parts being welded.

A welded joint is a permanent connection made by welding. It includes the weld, the adjacent base metal zone (HAZ), in which structural and other changes occurred as a result of the thermal effects of welding, and adjacent areas of the base metal.

Surfacing is the application of a layer of metal to the surface of a product by fusion welding.

A weld is a section of a welded joint formed as a result of crystallization of the molten metal of the weld pool. A weld pool is a part of the metal of the weld being welded, which is in a liquid state during fusion welding. The depression formed in the seam at the end of the welding process is called crater .

The metal supplied to the arc zone in addition to the molten base metal is called filler metal . Remelted filler metal introduced into the weld pool or deposited onto the base metal is called weld deposit .

The alloy formed by molten base and weld metals or only remelted base metal is called weld metal .

The weld layer is a part of the weld metal that consists of one or more beads located at the same level of the cross section of the weld. A bead is weld metal deposited or remelted in a single pass .

A pass is understood as a single movement in one direction of a heat source during welding and (or) surfacing. The part of the weld furthest from its front surface is called root .

A weld made in advance to prevent burn-through during multi-pass welding or deposited at the root of the weld to ensure guaranteed penetration is called a back-weld.

Depending on the working conditions, there are working , which absorb external loads, and binders (connecting), intended only for fastening parts of the product and not designed to absorb external loads. In addition, the technology for making welds describes a number of characteristics.

Thus, by the nature of the welds, welds can be single- or double-sided, and by the number of layers - single- and multi-layer, as well as multi-pass. Depending on the location of the seams in the structure, welding is performed in different positions: bottom, horizontal, vertical and ceiling.

Welds are also divided according to their position in space: “boat”, bottom, semi-horizontal, horizontal, semi-vertical, vertical, semi-ceiling and ceiling. Based on their length, seams are distinguished between continuous and intermittent.

And in relation to the direction of the acting force, seams are divided into longitudinal, transverse, combined and oblique.

Welds are distinguished depending on the type of welded joints, which are butt, corner, end, T and lap. However, in this case, only two types of welds are defined: butt and fillet. These and all of the above parameters will be discussed in detail later.

Welded joints and seams

Welded joints can be butt, corner, T-joint and lap joints (Fig. 5).

Rice. 5. Welded joints:

a – butt; b – angular; c – overlap; g – tee; d – end

A butt joint is a welded connection of two elements located in the same plane or on the same surface and adjacent to each other at their ends.

Corner is the connection of two elements located at an angle and welded at the junction of their edges.

An overlap weld is a welded joint in which the welded elements are located parallel and overlap each other. A type of lap joint is an end connection in which the side surfaces of the welded elements are adjacent to each other.

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

The part of the structure in which elements adjacent to each other are welded is called welded assembly .

Welds can be butt and corner welds (Fig. 6, a - d). Butt weld - a weld in a butt joint. Fillet weld is a weld of fillet, tee and lap joints. A variation of these types are cork and slotted seams, made in overlap joints.

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