How to cook thin stainless steel with a semi-automatic machine?
Semi-automatic welding of stainless steel (MIG) is the most common method of welding in a shielding gas environment. It is widely used in large industrial production and in car repair shops.
This type of welding is a high-tech process in which welding wire is automatically fed into the welding zone. Moreover, this wire is both an electrode and a filler metal.
Under the influence of the heating of the arc, it melts. The quality of the arc is affected by the choice of operating mode of the welder:
- current magnitude;
- wire feed speed;
- choice of shielding gas and its consumption.
With the correct choice of welding mode, the weld is formed quickly and evenly. The protective mixture is mainly a mixture of argon and carbon dioxide. In some cases, oxygen is used instead of carbon dioxide. The technology of the welding process using a semi-automatic machine must take into account the structure of the metal, its characteristics and chemical properties.
Welding stainless steel is quite simple, but requires compliance with a number of standards and conditions. Let's start with a description of the burner operation diagram.
Description of the burner diagram
1. burner body. To obtain a high-quality seam, it must have a certain angle of inclination to the surface of the metal being welded during the welding process;
2. nozzle. For optimal heating of the seam, it must be at a strictly defined angle and at an optimal distance from the surface being treated;
3. conductive tip. The assembly is located inside the nozzle;
4. electrode welding wire. The consumable passes through the conductive tip. A special wire is used for welding. It contains nickel, which improves the characteristics of the seam. The wire is fed into the burner in pulses, and the metal enters the bath one drop at a time;
5. welding arc. This is a source of thermal energy that heats metal and wire;
6. weld. It is obtained by welding parts;
7. weld pool. The area of molten metal in which a weld is formed;
8. base metal. Metal to be welded;
9. drops of electrode metal. The electrode welding wire melts and replenishes the weld pool in the form of drops;
10.gas protection. The area formed by the shielding gas.
Stainless steel welding methods
Welding stainless steel can be done in several ways:
- pulse welding;
- short arc welding. Used for welding thin metal;
- jet transfer welding. Used for welding thick-walled metal.
Pulse welding has become the most widespread, and therefore we will dwell on it in particular.
Pulse welding is a controlled process. It is carried out at an average current level, which reduces heat input and, as a consequence, the overall thermal affected zone.
This results in the optimal size of the weld pool, and this is very important for stainless steel. With pulse technology there is no splash of molten metal. This improves the safety of the welding process and saves material.
In addition, the time spent on cleaning the seam is reduced, and its surface is of a higher quality.
Stainless steel welding wire and its proper use
Special stainless steel welding wire is available in 3 grades:
- food grade stainless steel low alloy;
- food chemical stainless medium alloyed;
- high-pressure, heat-resistant, chemical, stainless, high-alloy.
When semi-automatically welding stainless steel, you should choose the right welding wire. To do this, you should take into account its features:
- the first two grades of the wire indicated above will ensure the mixing of all alloying elements. This burns out the metal (especially chrome). This is due to the fact that during the welding process aggressive environments are encountered, and a corrosion process occurs;
- The third brand of welding wire is special. When using it, there is no stress in the seam and, as a result, cracks. The seam is of better quality.
Preparatory work
Before welding begins, some preparatory work must be done:
- degrease the surfaces of the parts to be welded. In this case, it is necessary to completely remove the oxide film;
- Before the welding process itself, it is necessary to dehydrate the future seam. To do this, it is heated with a burner to a temperature T = 100°C. During the welding process of a continuous seam, all remaining excess boils away automatically. If the seam is intermittent (and in some other cases), then the area of the metal around the future seam is heated to T = 200°C (sometimes the entire workpiece is subjected to this procedure). Dehydration allows you to reduce the effect of moisture on the metal near the weld pool during the heating process during welding. It is not recommended to heat two different types of steel at the same time (only one type).
Semi-automatic welding of stainless steel.
Elimination of deformations
After welding is completed, any deformations must be eliminated. This is done as follows. The part is placed on an anvil and processed with a hammer through a “smoother”. The resulting “bubble” is tapped along the edge, carefully approaching the center of the deformation. On the other hand, this area should be heated with a burner, making circular movements with a diameter of 3060 mm.
Processing a stainless steel product after welding
After welding, the stainless steel product must be subjected to processing. Failure to comply with this requirement can quickly lead to serious consequences: the appearance of rust and even a decrease in its strength.
Processing consists of two stages:
- mechanical. It is produced by brushing, sandblasting, grinding, etc.;
- etching. Treatment of welds with chemically active substances that corrode scale. The latter can cause corrosion;
- passivation. Applying special agents to the weld seam, under the influence of which a protective film of chromium oxide is formed on the metal surface. After such treatment, the product is able to reliably resist corrosion.
Where will the service be provided?
- Website: http://ekb-profi.ru/;
- Address: Ekaterinburg, st. Equipment room, house No. 5;
Source: https://varimtutru.com/kak-varit-tonkuyu-nerzhaveyku-poluavtomatom/
How to cook thin metal using a semi-automatic machine
The invention of semi-automatic welding (the so-called MIG) is a kind of evolution in the manual electric arc welding process (the so-called MMA). Even taking into account the availability of MMA-type inverters, it is better to use MIG-type welding machines for everyday life. However, in order to fully appreciate all the advantages, you need to buy a semi-automatic welding machine and learn how to operate it correctly. However, understanding the principles of operation is not so difficult.
Advantages of semi-automatic welding
1. It is possible to weld parts made of thin sheet iron with a thickness of up to 0.5 millimeters.
2. Minimum degree of sensitivity to corrosion and other types of contamination of the metal being welded.
3. Low price compared to other types of welding.
4. Using a semi-automatic welding machine, it is possible to solder galvanized elements without damaging the zinc surface.
Doing the work yourself
Before you start semi-automatic welding, you should set up the machine:
1. Select the optimal welding current mode based on the thickness of the parts being welded. As a rule, the kit contains tables for selecting these values. It should be noted that welding at low currents is poor.
2. Adjust the wire feed speed. Adjustment is carried out using replaceable gears.
3. Check the correctness of the mode selection on trial elements and, if necessary, adjust. With the correct settings, you will produce a stable welding arc.
Types of welds
The different types of weld creation will differ mainly in the setup of the machine. Seams differ in the type of connection and the location of the parts during welding.
Position of seams in space:
· Vertical;
· Horizontal;
· Lower;
· Ceiling.
By connection type:
· Overlapping;
· At the joint;
· Corner;
· T-bar.
The simplest welding option is butt and overlap.
How to weld thin metal
There are no complex operations in this process. On the contrary, it is even easier to weld thin-sheet parts than thick ones.
Thin sheets can be welded using 2 methods:
· Normal – for any types of connections;
· Riveted - the parts are overlapped and welded through pre-created holes in the upper workpiece.
There are some rules for such welding:
1. The current strength and wire speed must be reduced.
2. It is not recommended to slow down the burner at one point. There will be sagging or burns.
3. The rivet method involves starting from the center of the part located below. If you start from the top, the molten mass will fill the hole, which will lead to poor penetration.
When it is not necessary to obtain airtight connections, you should not weld with continuous seams. To weld thin parts, you can weld spotwise at intervals of 1 to 5 centimeters.
Source: https://oxmetall.ru/svarka/kak-pravilno-varit-poluavtomatom-tonkij-metall
How to weld thin metal semi-automatically
Welding thin metal is a challenge even for some experienced welders. Beginners in welding generally have a hard time. The rules that apply here are completely different from those when welding thick products: there are many features and difficulties, which makes it more difficult to select modes and electrodes. It’s easier to do this with semi-automatic welding machines, but they are quite rare in everyday life; inverters are much more common. We will talk about welding thin metal with an inverter.
And the first difficulty when welding metal of small thickness is that you cannot heat it too much: it will burn out and holes will form. Therefore, they work according to the principle “the faster, the better” and there is no talk of any trajectories of electrode movement at all. Thin sheet metal is welded by passing the electrode in one direction - along the seam without any deviations.
When welding thin metals, the sheets overheat and bend
The second difficulty is that you need to work at low currents, and this leads to the fact that the arc has to be short. With a slight separation, it simply goes out. There may also be problems with arc ignition, so use devices with a good current-voltage characteristic (no-load voltage above 70 V) and smooth adjustment of the welding current, which starts from 10 A.
Another trouble: with strong heating, the geometry of thin sheets changes: they bend in waves. It is very difficult to get rid of this shortcoming. The only option is to try not to overheat or remove heat (read about the method with heat-dissipating pads below).
When butt welding thin sheets of metal, their edges are carefully processed and cleaned. The presence of dirt and rust will make welding even more problematic. Therefore, carefully align and clean everything. The sheets are placed very close to one another - without a gap. The parts are fixed with clamps, clamps and other devices. Then the parts are tacked every 7-10 cm with short seams - tacks. They will prevent the parts from shifting and are less likely to bend.
If you clean the edges well, you can get a good seam
How to weld thin metal with an inverter
Welding machines that produce direct current are good because we can weld with reverse polarity. To do this, we connect the cable with the electrode holder to “+”, and connect “-” to the part. With this connection, the electrode heats up more, and the metal heats up minimally.
Read about how to choose a welding inverter for your home or cottage here.
It is necessary to cook using the thinnest electrodes: from 1.5 mm to 2 mm. In this case, you need to choose one with a high melting coefficient: then even at low currents the seam will be of high quality. The current is set to small. For electrodes measuring 1.5 mm it should be about 30-45 amperes, for a “two” - 40-60 amperes. In fact, sometimes they put it lower: it is important that you can work.
Metal thickness, mm0.5 mm1.0 mm1.5 mm2.0 mm2.5 mm| Electrode diameter, mm | 1.0 mm | 1.6 mm - 2 mm | 2 mm | 2.0 mm - 2.5 mm | 3 mm |
| Current strength, A | 10-20 amps | 30-35 amps | 35-45 mm | 50-65 mm | 65-100 mm |
To ensure that the metal heats up less, the parts are placed in a vertical or at least inclined direction. Then they cook from top to bottom, moving the tip of the electrode strictly in this direction (without deflecting or returning). The tilt angle is forward, and its value is 30-40°. This way, the heating of the metal will be minimal, and this is one of the most important tasks for welding thin metals.
Electrode positions for welding and their use
General recommendation for choosing electrodes for welding thin metals: buy high-quality imported electrodes for such work. There will be many fewer problems.
Read about making a shed on a metal frame here.
Techniques and methods for welding thin sheet metals
Sometimes thin sheets need to be welded at an angle. In this case, it is more convenient to use the flanging method: the edges of the sheet are bent to the required angle, fastened with short transverse seams every 5-10 cm. Then they are welded as mentioned above: with a continuous seam from top to bottom.
The video shows how to weld thin sheet metal with an electrode using a welding inverter. The flanging method is used: the edges of the parts are bent, then secured in several places with short seams. This is followed by welding with a thin electrode 2 mm thick.
Source: https://respect-kovka.com/kak-varit-tonkiy-metall-poluavtomatom/
Welding of thin metal tig, semi-automatic, gas – Welding
The further we go, the more vehicles, technical equipment and structures are produced using thin metal. These are cars, boats, profile pipes, wall cladding and much more. And since no surface is immune from mechanical damage, welding of thin metal is becoming a common type of repair.
Kinds
All types of welding are divided into three large categories:
- thermal,
- thermomechanical,
- mechanical;
The first is produced by melting using thermal energy, in the second, in addition to thermal energy, pressure is present, in the third case, pressure and mechanical energy are present.
Thermal welding comes in several types, depending on the heat source - electric arc, gas torch, plasma jet, laser beam, etc. For thin metal, electric arc welding is most often used, less often gas welding.
Electric arc, in turn, also comes in several types: non-consumable electrode (non-metallic rod or refractory metal) or consumable electrode; using direct or alternating current; open arc (in air), submerged arc (using a protective substance), in inert gas.
For thin sheets, manual argon arc welding with a tungsten (non-consumable) electrode TIG (abbreviation tungsten inert gas - tungsten/inert gas) is used.
Its main disadvantages are: firstly, dependence on the electrical network, and secondly, in order to avoid metal burns, the welder needs to master the equipment perfectly.
Welding using MIG/MAG technology, semi-automatic with a consumable electrode (wire), is somewhat easier to perform, but it also requires mastery of skills.
Advantages of TIG: compact equipment, narrow heat-affected zone and, as a result, more accurate seams. The same can be said about semi-automatic.
The fundamental disadvantage of semi-automatic machines is that they are more expensive than TIG equipment.
Gas welding (usually oxygen-acetylene) is much easier for beginners and can be carried out far from sources of electricity.
Its disadvantages: the need to constantly fill the cylinders; large thermal impact area (due to which the surface is subject to deformation); There should be nothing flammable around the work site to avoid a fire. Acetylene is more expensive than electricity, which means the work is more expensive.
Principle of operation
Electric arc welding is so called because the heat source in this process is an electric arc. It occurs between two electrodes, one of which is the electrode of the welding machine, and the second is the surface of the sheets being processed.
Due to thermal effects, the sheets partially melt, the so-called. weld pool (cavity filled with liquid metal).
The treatment area is protected from the effects of atmospheric oxygen by a layer of inert gas - argon, which is supplied from the apparatus to the outside through a special gas nozzle.
In gas welding equipment, the source of thermal energy is a gas torch. It is formed due to the combustion of acetylene when it combines with atmospheric oxygen. As a result, the treated surface melts and a weld pool appears.
Equipment
Inverter – welding machine. It includes a transformer that lowers the mains voltage to the required value and absorbs its surges.
This is the most popular type of equipment, as it is economical in terms of energy consumption and provides an even supply of current, thereby achieving good quality welding seams. There are several types of inverter welding.
TIG technology includes TIG AC/DC (alternating current operation) and TIG-DC (direct current operation).
The device is equipped with electrodes. For thin sheets (up to 3 mm), electrodes with a diameter of 0.5 - 2.5 mm are used when applying a current from 10 to 90 amperes. With a sheet thickness of 3 mm, an electrode diameter of 3-4 mm and a current of 140 - 180 are possible, respectively. If these parameters are not observed, burnouts are inevitable.
The semi-automatic device consists of a power source, a wire feed mechanism, a torch, and a control system. Semi-automatic welding, like TIG, is carried out in an environment of inert gases supplied through a special nozzle.
It is easier to cook with a semi-automatic device than with an inverter. Some models have the ability to weld with an electrode.
There are universal inverter semi-automatic machines that work with equal success in semi-automatic, manual, and TIG modes.
Gas equipment consists of an acetylene generator, a water seal (which, in fact, is a safety device against explosion), cylinders (for storing and transporting gas), a reducer (for reducing the pressure in the cylinder to operating pressure), hoses and the burner itself.
Surface preparation
Before starting welding work, it is necessary to clean the surface of the sheets from all unnecessary things: remove dirt, rust, paint, scale, soil, lubricants, anti-corrosion coating, etc. First of all, none of this conducts electricity.
Secondly, under the influence of high temperature, gases can be released from some substances, which will lead to splashing of liquid metal. Due to the same gases, the seam will become porous, i.e. ugly and unreliable.
Auto-preservatives contain solvents that will burn, release toxic fumes, and so on.
You can remove dirt with a wire brush. It also makes sense to preheat the edges of the sheets with a gas burner and level them. This is especially true if you are going to butt weld.
Preliminary work
Before starting to work with the TIG method, it is advisable to test the device on pieces of metal similar to the one that is to be welded. This way you can check whether the selected current strength is optimal.
If the current is too high, the test piece will melt through. At the very least, it will sag and a drop will appear on the inside. If the current is insufficient, then there will be no penetration. In both cases, the current must be changed, reduced or increased.
Once you reach the optimum, you can start working.
If it is assumed that the seam will overlap, you first need to connect the sheets to each other with small seams, the so-called. potholders. The purpose of this procedure is to fix the fastening of the sheets to each other so that their relative position does not change, and to eliminate the gap.
With a short seam length, the size of the tacks is no more than 0.5 cm, and the distance between adjacent ones is 5-10 cm. If the seam is planned to be long, then the size of the tacks will be 2-3 cm, and the interval will be from 30 to 50 centimeters. You can use fastening with self-tapping screws, clamps, bolts, etc. for the same purpose.
This type of fixation should also be used if you are going to butt weld. Otherwise, a gap will form between the parts, and you risk burning it even more.
Some experts believe that it is better not to cook overlapping seams with gas, because... this would require heating the metal to too high a temperature, causing greater deformation.
If welding is electric arc, you need to make tacks with short touches, 1-3 seconds, no longer. Pull the electrode back and quickly return it until the surface cools down. Otherwise there will be a burn through.
How to cook with an electrode
A long seam must be made in pieces, moving the electrode to the cold area: top, bottom, middle, top again. The shorter the length of the “stitch”, the less deformation of the sheets will be.
When welding butt joints, it makes sense to place an additional gasket under the seam.
You can weld sheets thinner than 1 mm using TIG technology without such a gasket only with a good inverter, imported electrodes and if you have welding skills.
If it is possible not to remove the substrate, it is better to use a narrow (up to 1.5 cm) strip of the same metal. Weld it to the seam. In addition, it will eliminate the gap if there is one.
If this is not possible, then it is advisable to place a thick piece of copper. Copper will remove heat and reduce the likelihood of burnout.
At the end of the work, the backing will need to be removed. If a copper gasket is not found, you can use a steel gasket for this purpose, and after welding, carefully remove it using an angle grinder.
How to cook with gas
The flame of a gas burner is divided into three areas: the core, the reduction zone and the torch. The core has clear boundaries and is close to a cylinder in shape. The diameter is equal to the diameter of the burner mouthpiece, and the length depends on the flow rate of the gas mixture. Behind the core is the middle zone, the so-called.
restorative, high temperature zone. It is called reducing because it contains hydrogen and carbon oxides, which contribute to the deoxidation of the metal in the weld pool, i.e. binds oxygen. Thanks to this, the seams are smooth, without pores or blisters.
During work, it is important to ensure that the flame touches the metal in this particular area.
Gas welding can be right or left. With the left, the burner mouthpiece is led from right to left, the filler wire (if used) is moved ahead of the flame, and the flame itself is directed to the cold area where no processing has yet taken place.
Welding of thin metal is usually left-handed. The mouthpiece should be guided in a smooth wavy line. For sheets less than 1 mm thick with flanged edges, filler wire is not required.
The flame power should be set at a rate of 100 to 130 cubic decimeters of acetylene per hour per metal thickness of 1 mm.
Security measures
Welding work involves a number of specific factors that are hazardous to health and life.
- 1. When working with electricity, there is a risk of electric shock;
- 2. When working with gas, there is a danger of explosion in acetylene generators and gas cylinders;
- 3. Burns to the skin and eyes from arc radiation and metal splashes;
- 4. Harmful emissions - gases, vapors;
- 5. Fire danger.
In this regard, the following safety rules are provided:
- 1. Grounding of electrical equipment, ensuring insulation;
- 2. Regular inspection of electrical equipment for serviceability and tightness;
- 3. Checking the tightness of gas cylinders, the serviceability of the water seal and gearbox;
- 4. Use of personal protective equipment: helmet, goggles, mittens, protective shield, respirator;
- 5. Absence of flammable objects and materials nearby. Anything that cannot be removed must be isolated with non-flammable protective materials.
Source: https://svarkaman.ru/tehnologiya/svarka-tonkogo-metalla-tig-poluavtomaticheskaya-gazovaya.html
How to cook stainless steel semi-automatically in a carbon dioxide environment: video, tips
Welding stainless steel with a semi-automatic machine can be quite difficult not only for a beginner, but also for an experienced specialist. Such difficulties are primarily associated with the characteristics of the metal itself, for high-quality welding of which it is necessary to correctly select the operating welding modes and the appropriate consumables.
Semi-automatic welding machine for metal welding in a protective gas environment
Types of stainless steels
The main alloying element of steels classified as stainless steels is chromium. It is thanks to this element, which stainless steel must contain at least 12%, that an oxide film is created on its surface.
Despite the very small thickness of such a film, sometimes not exceeding the size of several atoms, it provides reliable protection of the metal from corrosion.
In addition, if this protective film is accidentally or intentionally damaged by mechanical force, then after some time it will restore its integrity.
The chemical composition of the vast majority of stainless steel grades, in addition to iron, carbon and chromium, may contain chemical elements such as nickel, titanium, niobium and molybdenum. These elements, found in stainless steel in fairly small quantities, improve both the anti-corrosion and mechanical characteristics of the alloy.
Chemical composition of the main grades of stainless steel
Stainless steels, depending on the characteristics of their internal structure, can belong to one of the following types. Martensitic
These are alloys containing 17% chromium and 0.5% carbon. Stainless steel with this structure is hard and highly brittle and can only be successfully used in slightly aggressive environments.
Austenitic
The chemical composition of such steels, in addition to chromium and carbon, also contains nickel, which increases the austenitic region in their structure. The distinctive qualities of such alloys, classified as non-magnetic, are high corrosion resistance and strength, optimally combined with good ductility.
Ferritic
This includes stainless steel alloys containing no more than 0.12% carbon and up to 30% chromium. This stainless steel, characterized by a good ratio of high strength and ductility, is resistant to thermal hardening and can be successfully used in conditions of exposure to aggressive environments.
Semi-automatic welding of stainless steel in a protective environment ensures high-quality connection of products
Properties and weldability of stainless steel
Steels classified as stainless steels are difficult to weld materials, which is explained by a number of their physical and chemical characteristics. When you decide to cook stainless steel with a semi-automatic machine, you must take into account a number of important parameters. Only in this case can you count on the resulting welded joint being of the required quality and reliability.
Compared to steels of other categories, stainless steel has a fairly low (on average two times) thermal conductivity. Because of this, heat is removed from the welding zone very poorly, as a result of which the metal is subjected to significant overheating, which negatively affects its corrosion resistance. To avoid such negative consequences, welding of stainless steel using a semi-automatic machine is performed at a reduced current (by 15–20%), and the parts to be joined are subjected to additional cooling.
Approximate modes of semi-automatic welding in a shielding gas environment
With significant heating (over 500°), carbide compounds are formed at the boundaries of the crystal lattice of stainless metal, which cause a phenomenon such as intergranular corrosion. As a result, delamination of the internal structure of the metal occurs and corrosion processes develop. To avoid this, they resort to more intensive cooling of the products being joined, for which ordinary water can be used.
It is also difficult to cook stainless steel (including in a protective gas environment) because it has a tendency to thermal expansion. Significant expansion of the joined products that occurs during semi-automatic welding leads to the formation of cracks both in the weld and in the base metal. Meanwhile, this phenomenon can be avoided if a wider gap is left between the parts being welded.
A high-quality stainless steel weld may be slightly grayish, but not dark
Stainless steel, due to the characteristics of its chemical composition, has a fairly high electrical resistance, which causes significant heating of the electrodes used for semi-automatic welding. In this regard, for welding stainless steel, electrodes made of wire with a certain chemical composition are used, and the length of the rods, if they contain chromium and nickel, should not exceed 350 mm.
Consumables
Good results in joining stainless steel parts can be achieved by welding performed in a shielding gas environment. To weld using this technology, naturally, you will need both special equipment and appropriate consumables, which are filler wire and the gas itself.
The purpose of gas in semi-automatic welding is to protect the molten metal in the weld pool from oxidation. The gas used for such protection should not itself react with the molten metal so as not to have a harmful effect on it. That is why inert argon mixed with a small amount of carbon dioxide is predominantly used as a protective medium.
On the left is a weld made in a carbon dioxide environment. On the right - in argon (98%)
The standard composition of the gas mixture used when welding stainless steel with a semi-automatic machine includes 98% argon and 2% carbon dioxide. In some cases, in order to reduce the cost of welding, it is possible to use a gas mixture consisting of 70% argon and 30% carbon dioxide.
To weld stainless steel while obtaining a high-quality and reliable weld, it is very important to choose the right filler wire, which should also be made of stainless steel. In cases where it is not possible to use shielding gas, semi-automatic welding is carried out in a normal environment, but special flux-cored wire is used to perform it. Meanwhile, the use of the latter leads to the fact that the welds may become covered with a layer of rust over time.
Some features of the technology
The use of special semi-automatic welding machines mentioned above can significantly improve the quality of stainless steel welding, as well as simplify the process of its implementation. The use of such equipment allows you to solve several technological problems at once, including:
- supply of filler wire to the joint formation zone;
- supply of shielding gas to the welding zone;
- cooling of the welding torch;
- ensuring the convenience of making welded joints in hard-to-reach places.
Semi-automatic welding equipment
In products made of stainless steels, during the welding process, significant internal stresses are formed, which are removed by their further heat treatment - heating to a temperature of 660–760° and slow cooling in the open air.
Preparation for welding work
Before welding products made from stainless steel using a semi-automatic machine, they must be properly prepared in order to obtain a high-quality and reliable connection. The process of such preparation is as follows.
- The surface of the parts to be joined is thoroughly cleaned using a metal brush and then degreased, for which the most common solvents can be used.
- To remove residual moisture from the surface of the product, it is heated to a temperature of 100°.
Preparing stainless steel for welding the manifold
Welding rules and methods
As mentioned above, in order to qualitatively weld stainless steel using a semi-automatic machine, it is necessary to correctly select the filler wire from which the weld will be formed. It is optimal if the degree of alloying of the wire exceeds that of the base metal. This is explained by the fact that alloying elements contained in the chemical composition of the wire will burn out of the metal during its melting, therefore their content must be taken into account with a reserve.
For semi-automatic welding of stainless steel, wire with an ultra-low carbon content and high silicon content, resistant to oxidizing environments, is used
For welding products made of stainless steel, three main methods are used:
- short arc method (used in cases where small thickness products are welded);
- jet transfer method (allows you to weld parts even of very significant thickness);
- pulsed (the most universal technology that allows you to perform welding work with high productivity and at the same time save wasted resources).
Each of the listed methods has certain features, but there are also general rules that should be followed when using each of them. Let's look at these rules.
- The torch body is located at the opposite angle to the progress of the seam to provide a high-quality overview of the latter.
- The torch nozzle, through which shielding gas and welding wire are supplied, is located at a distance of approximately 12 mm from the surface of the products.
- The filler wire, melted as a result of the burning of an electric arc, is fed into the zone of the weld being formed in small drops.
Burner position: approximately 11 o'clock
In addition, there are general recommendations for welding work that uses shielding gas.
- Stainless steel should only be cooked with reverse polarity.
- The angle at which the welding machine nozzle is located should ensure good penetration of the joint and a small width of the seam being formed.
- The protrusion of the wire from the nozzle of the welding machine should not exceed 12 mm.
- The gas flow rate that forms the protective environment should be in the range of 6–12 m3/min.
- The gas supplied to the welding zone must first be passed through a drying agent, which is copper sulfate.
- To minimize the splashing of molten metal from the welding area, the surface of the products to be joined is treated with an aqueous solution of chalk.
- To get a beautiful and high-quality weld, it should not start and end at the very edge of the parts being joined. It's better to retreat some distance. The welding itself, which is important, is performed without oscillatory movements to the sides of the seam being formed.
Technique for welding thin metal with an inverter
[Welding sheets of thin metal with an inverter] allows you to quickly and efficiently produce a metal product.
Thin-sheet material is a material with a thickness of up to 5 mm; it is often used in the production of blanks for cars, motor boats, as well as for the manufacture of pipes, various hull structures, etc.
The main problem when welding thin sheets of metal is the high probability of damage.
The reason for this may be careless movement of the welder, as a result of which a burn may form on the workpiece.
In addition, welding of thin metal, carried out by a person without experience, may turn out to be of poor quality due to non-compliance with the technology.
Since the welding process is performed by an inverter exclusively using low current, even a slight gap in the working distance between the part and the electrode should not be allowed.
Otherwise, a break in the electric arc cannot be avoided. Therefore, it is not recommended to start welding thin sheets with an inverter without knowledge of the process features.
Next, we suggest that you familiarize yourself with a step-by-step lesson, specially created for novice welders, with which you can learn how to properly weld thin metal with an inverter semi-automatic machine.
Step-by-step guide to welding thin metal with an inverter
Welding thin metal requires, like any other welding process, to have protective clothing on hand: a special welding helmet, gloves and outer clothing made of rough fabric, but in no case should you wear rubber gloves.
Step one
We adjust the welding current and select an electrical conductor that will allow it to operate as an inverter.
We take the welding current indicator based on the characteristics of the metal sheets being joined.
Typically, the manufacturer indicates the current strength for specific cases on the inverter housing.
We use electrodes for inverter arc welding with a diameter of 2-5 mm. Next, insert the electrical conductor into the holder and connect the ground terminal to the workpiece.
To prevent sticking, do not bring it to the part too sharply.
Step two
Welding thin metal using an inverter machine begins with igniting the arc.
Using the electrode, we pointly touch the line to be welded a couple of times at a slight angle, which will activate it.
We keep the electrical conductor from the product to be welded at a distance that will correspond to its diameter.
Step three
If all of the above was done correctly, you should get a high-quality seam joint.
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At the moment, there is scale or scale on the surface of the weld, they need to be removed using an object, for example a hammer.
The following video for novice welders will demonstrate how to properly connect thin sheets of metal with an inverter.
How to control arc gap?
The arc gap is the distance formed during welding between the elements being connected and the electrode.
It is imperative to maintain a stable size of the specified distance while operating the inverter.
If you weld thin metal with an inverter and at the same time maintain a small arc gap, then the welded seam joint will be convex for the reason that the main part of the metal does not heat up well.
If you weld thin metal with an inverter semi-automatic and at the same time keep too large a distance between the electrical conductor and the workpiece, then such a large gap can interfere with weld penetration.
The electric arc will jump, the deposited metal will lie crookedly.
A correct and stable distance will allow you to obtain a high-quality seam joint; however, it is necessary to weld thin metal with an inverter, as mentioned above, with a gap corresponding to the diameter of the electrode.
Having gained experience and the ability to control the inverter welding arc length, you will be able to achieve optimal results.
Due to the electric arc, which is fed through the gap and melts the base metal, a weld pool is formed. It also helps to move the molten metal into the weld pool.
Features of the formation of a weld seam
If you move the electrode too vigorously during the welding process, then all that can be achieved is a deformed joint.
This fact is explained by the fact that the line of the weld pool is below the level of the base metal, and if the penetration of the arc into the base metal is strong and fast, it pushes the pool back, resulting in a seam.
That is why it is necessary to control that the welding seam line is located on the surface of the metal sheets.
A high-quality seam can be achieved through circular and zigzag movements of the electrode along the surface to be joined.
When moving in a circle, it is recommended to monitor the level of the connection, distributing the weld pool as evenly as possible.
When performing zigzag actions, you need to monitor the formation of the seam line alternately in three positions: from one edge, on top of the weld pool, from the second edge.
Here we should not forget that the weld pool moves with heat, which is very important when changing the working direction.
If there is a lack of electrode metal, an undercut is formed - a narrow groove in the base metal along or along the edges of the weld, appears as a result of the lack of metal to fill the pool during transverse movement.
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To prevent the formation of such a side recess or undercut, it is recommended to monitor the outer boundaries and weld pool, and, if necessary, adjust the width of the groove.
The welding pool is operated by the force of the electric arc located at the tip of the electrical conductor.
Do not forget that when working with a welding product at an angle, the pool will not be pulled, but will be pushed.
Therefore, a vertically positioned electrical conductor allows for less convex welding joints.
The process is explained by the fact that at this time all the thermal energy is concentrated under the electrode, the weld pool is pushed to the bottom, melts and is distributed around.
When the product is slightly tilted, all the force is pushed back, causing the weld to float up.
If the electrode product is tilted too strongly, the force is transferred towards the suture line, which does not allow effective control of the bath.
To achieve a flat seam connection, the electrical conductor is tilted at different angles.
In this case, welding should begin at an angle of 450, which will make it possible to control the pool and correctly connect the metal using a semi-automatic machine.
Welding thin sheet metal with a consumable electrode
In order for the process of welding thin metal with a semi-automatic machine to be successful, it is necessary to use an electrical conductor with a suitable diameter.
For example, for sheets of thin metal with a thickness of up to 1.5 mm, you need to use products with a diameter of 1.6 mm.
Correctly welding thin metal with a consumable electrode means preventing overheating during the welding process, which can lead to burning through the product.
The electrical conductor is moved along the line to be welded at an average speed; as soon as there is a risk of combustion, the speed is increased.
The current strength during inverter welding of metal sheets should not exceed 40 Amperes.
When selecting the current strength for working with a consumable electrode, it is better to make a test weld, which will simplify the solution of the task.
In this case, a test product can be cooked semi-automatically in different modes, taking into account the speed of movement of the electrode.
It is necessary to cook in such a way that it is possible to completely ensure penetration of the steel edges without burning the material.
The peculiarity of welding thin metal with an inverter with a consumable electrode is the instantaneous melting of the edges, which does not allow full monitoring of the weld pool.
That is why it is better to start semi-automatically welding thin sheets of material after gaining experience.
In the process of welding thin-sheet metal products, spot or intermittent welding technology can be used.
Due to the short operation of the arc, tacks are formed, subsequently the electric arc is extinguished, then the process is repeated at a distance equal to the size of 2 or 3 electrode diameters.
It is better to minimize the period between creating points so that the molten metal does not have time to cool.
This method is ideal if you need to weld leaky structures made of thin sheets with an inverter. Point clamps will eliminate the possible risk of metal warping.
How to choose polarity when operating an inverter?
Polarity is the basis of a quality welded joint. Direct polarity provides a reduced heat input into the metal base with a narrow but deep melting region.
With reverse polarity, a reduced supply of thermal energy is observed in a material with a wide and shallow melting region of the base metal.
It is the polarity of the electrons that needs to be paid attention to before starting work on the inverter.
If you weld metal using direct current, you can use the positive and negative charge of the source.
But at the same time you need to know where to connect which charge.
Here it is necessary to take into account that if a positive charge is provided to the material being welded, it will become very hot.
If this charge is connected to an electrical conductor, then the electrode will become very hot and burn, which can lead to burning of the metal.
The way out of the situation is to reverse the polarity of the inverter and the optimal current indicator.
During operation of the inverter, the electrode is connected “+” to the inverter arc, and “-” to the sheet of metal.
Practical advice for beginner welders
The following few tips and thematic video material will also be useful for novice welders:
- The ability to observe the weld seam and control it from all sides during the arc welding process with an inverter will allow you to obtain a high-quality result and eliminate the formation of burnt holes;
- During the welding process, the electrical conductor must be kept as close to the workpiece as possible until a red spot begins to appear. This will mean that there is already a metal drop underneath it, due to which the metal sheets are connected;
- When the electrodes slowly move along a metal surface, hot drops of metal that appear connect segments of sheets and thereby form a welding seam.
Having studied the above information and watched the videos, it will be much easier to weld thin sheets of metal with an inverter.
Source: https://rezhemmetall.ru/svarka-tonkogo-metalla-invertorom-i-elektrodom.html
How to make perfect homemade chebureki
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There is no classic dough for this dish. We offer several of the most common and successful options.
All types of dough will yield thin, crispy pasties with bubbles. The dough made with water at room temperature and with kefir will be less bubbly, but no less tender and tasty.
Cooking may require less or more flour than indicated in the recipe. This largely depends on its quality. Focus on the dough itself: it should be elastic, pliable and not sticky.
- 500 g flour;
- 1 teaspoon salt;
- 50 ml vegetable oil;
- 150 ml boiling water.
Add salt and butter to the flour and mix lightly. Pour boiling water in portions, constantly stirring the mixture. Then knead the dough with your hands until smooth.
Cover with film or a dish and leave at room temperature for 30 minutes.
Ingredients
- 400–450 g flour;
- 1 teaspoon salt;
- ½ teaspoon sugar;
- 50 ml vegetable oil;
- 200 ml water at room temperature.
Preparation
Combine flour, salt and sugar. Add oil and water and knead into a smooth dough.
Cover with film, a bowl or wrap in a bag and leave at room temperature for 30 minutes.
