Is it possible to weld aluminum at home with an inverter?

Aluminum is not the most durable material, so it is not surprising that objects made from it often break. It is not necessary to take them to a workshop; you can repair them at home by welding aluminum with an inverter. However, to create reliable connections, you need to take into account the extraordinary properties of this capricious material.

Aluminum - properties and features

Due to its chemical and physical properties, aluminum is widely used in various fields of human activity.

For welding various structures or parts, not only aluminum, but also alloys made from it can be used. True, the process itself can only be done by experienced welders.

Because this metal is capricious, and in order to weld it efficiently, you need high qualifications.

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The difficulties of welding aluminum are due to a number of characteristic features of the metal:

High turnover. Under the influence of high temperatures, the metal loses strength and during the welding process, the molten part of the metal can destroy the lower, unmelted part. In this case, the aluminum will simply leak out through the seam. The difficulty of controlling the situation is aggravated by the fact that the color of the metal does not change when heated. Therefore, in order to maintain the shape of the weld pool, welders use special linings made of ceramic or metal;
Formation of an oxide film. When interacting with oxygen, a film appears on the surface of aluminum, the properties of which differ from its properties in higher density and refractoriness. During welding, aluminum oxide prevents the metal from fusing into a monolithic seam. Therefore, it is removed using cathode sputtering. And in order to prevent the appearance of an oxide film, the welding area is protected from contact with air. For this, argon welding is used;
With a sufficiently high coefficient of linear expansion, aluminum has a low elastic modulus, which can provoke deformation of the structure being welded. The likelihood of deformation can be reduced using various technological methods - electric welding in optimal mode or heating;
The welding process contributes to the appearance of porosity in aluminum alloys. This happens because metal compounds contain hydrogen, which escapes through newly formed pores. Also, with an increased silicon content, small crystallization cracks may appear, which can significantly weaken the weld;
Aluminum has high thermal conductivity. Therefore, to weld it, powerful sources of welding current are required;
During welding, hot cracks may form in aluminum seams. This occurs due to processes of internal changes at the moment of solidification of the molten metal. To prevent their occurrence, special modifiers are used that are added to welds. Also, it is undesirable for the seams to be close to each other.

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In addition, at home there are often cases when welding is applied to aluminum alloys of an unknown brand, which is not always feasible without special materials and special welding modes.

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Rules for preparation and conduct

It is best to weld critical joints of aluminum workpieces using argon arc welding . The method using an inverter and rod fusible electrodes allows you to obtain quality sufficient for home repairs or construction. How to weld aluminum blanks at home using an inverter?

The strength and durability of the seam is largely determined by the quality and thoroughness of the preparatory work. They are designed to remove the layer of oxides with a high melting point that covers any part made of aluminum or its alloys upon contact with air.

Difficulties in welding aluminum products

Parts made of aluminum are coated with an oxide film, which has a high melting point of 2000 degrees Celsius. While the metal itself melts at 600 degrees. Therefore, before starting work, the film must be removed: chemically or mechanically. It is worth remembering that welding aluminum should begin immediately after removing the refractory film in order to avoid re-oxidation of the surface - this occurs when the metal comes into contact with oxygen contained in the air.

It must be taken into account that the strength of products decreases with sudden temperature changes. And due to the fact that the electric arc heats up to a high temperature, the aluminum melts and begins to flow out of the welding zone.

Additional complications are created by the fact that the color of the metal does not change when heated. Therefore, it is difficult to control that the weld is the same size throughout the entire area. The welded structure may change shape due to the low elastic modulus. For the same reason, when the product cools down, microcracks can form in the area of the weld pool.

Knowing about these difficulties, you can weld aluminum yourself using an inverter, without the help of specialists.

Welding requirements

Welding aluminum must strictly follow the following rules:

Welding is carried out only under the protection provided by inert gases. As a rule, argon and its mixture with helium are used. Accordingly, the inverter apparatus must be equipped with argon arc welding equipment.
It is better to use tungsten electrodes for aluminum - they do not melt. During work, you need to periodically clean off oxides from them, otherwise the quality of the seam will deteriorate.
The work is carried out using alternating electric current, the strength of which is set greater than when working with steel products.
To prevent the weld from deforming due to temperature changes, it is necessary to warm up the working surface before welding.
Filler electrodes for aluminum are preheated by placing them in a muffle furnace.

Equipment for work

For welding aluminum or aluminum alloy workpieces can be used

inverter-type devices that differ in performance and degree of automation of work processes. If it is not possible to purchase a semi-automatic device, you can install an attachment to the inverter, which will generate alternating current. This will allow you to work efficiently.

In the case when aluminum is welded with a TIG inverter, non-consumable tungsten electrodes and filler wire with a diameter of 2-5 mm of several markings are used: AO, AD and AK. It contains a large number of magnesium alloy additives.

You can also use the following electrodes for welding aluminum with an inverter: Russian brands OZA, OZR OZANA; or imported samples of OK 96.20, OK 96.40, Kobatek-213 brands.

The wire for semi-automatic welding inverters for aluminum has a diameter of 0.8-1 mm. It is produced in reels that weigh half a kilogram. It is optimal to use wire made of lithium-silicon alloy of two grades - ER 4043 and ER 5356. Or wire grades made of magnesium alloy with aluminum - Sv-AK 5 or Sv-AMg 5.

The argon arc (AC TIG) method of welding aluminum parts is mainly used for detailed welding. As a result, no pores or rough seams are formed. Alternating current allows you to melt the refractory oxide layer on the surface of the material and create a weld pool, which is necessary for connecting structural elements. When using a device of this type, it is possible to repair thin-walled products made of pure metal and its alloys. However, it is quite sensitive to contamination of the electrodes used - for this reason, they must be cleaned in a timely manner.

Electrodes for aluminum

The most common brands of electrodes for welding aluminum alloys: OZA-1, OZA-2, OZANA-1, OZANA-2, OK96.20. Electrode rods are made from welding wire and coated with a mixture of chloride and fluoride salts. The coating thickness is no more than 0.3...0.5 mm per side.

Electrodes for aluminum OZANA-2

Let's consider a more detailed purpose of each electrode.

OZA-1 - for parts and structures made of technically pure aluminum A0, A1, A2, A3. Welding with preheating along cleaned edges.
OZA-2 – for welding casting defects and surfacing aluminum-silicon alloys AL-4, AL-9, AL-11.
OZANA-1 - welds technically pure aluminum with a thickness of products more than 10 mm. Preheating at a temperature of 250…400 C.
OZANA-2 – for AL-4, AL-9, AL-11 alloys, surfacing and welding of casting defects. Can be used as a connecting material for products made of duralumin and silumin.
OK96.20 – aluminum-manganese alloys AMts; aluminum-magnesium alloys AMg2; AMg3; AMg5; AMg6; aluminum-silicon alloys AL-4; AL-9; AL-11. Suitable for duralumin

Aluminum electrodes are more expensive than conventional electrodes and are very hygroscopic, i.e. they absorb moisture from the surrounding air.

Instructions for performing the work

Aluminum welding with an inverter is carried out according to a strict algorithm.
First of all, the machine for inverter welding is set up. The toggle switch is switched to alternating current mode corresponding to the AC value. The next step is to set the polarity balance to a value - when working with products made of pure aluminum, it must be shifted from the original position (50/50) to the negative side, and when welding alloys - to the positive side. The value of the welding current is set depending on parameters such as sheet thickness and electrode diameter. For example, with a sheet thickness of 2 mm and a filler wire diameter of 3 mm, it is set to a value of 60 Amperes.

The thickness of the product also determines the slowing down of the attenuation of the electric arc to fill the crater at the end of the weld pool. So, when working with a 2mm sheet, this value is set to 3 seconds.

The settings of the welding inverter for aluminum welding are completed by setting the time and intensity of purging the seam with an inert gas (it is impossible to work without argon), which is required in order to cool the weld seam.

After setting up the equipment, it is necessary to prepare the workpiece itself - clean it of the film that increases the heat resistance of the material. Both mechanical cleaning (iron brush, sandpaper) and chemical cleaning are used. In the latter case, an aqueous solution of zinc chloride or another solvent is used. Then the product must be preheated to 400 degrees. Only after this can you proceed to finishing welding work. You should act slowly so that the elements being welded are heated with the same intensity.

In order for the resulting weld to be uniform with characteristic ribbing, the filler wire or electrodes on aluminum for welding must be applied with light touches at a certain angle - 15 degrees, starting from the beginning of the weld pool. In this case, several passes are made along the seam.

Thus, if you have the necessary equipment, you can weld aluminum products conscientiously at home using an inverter. It is important to consider that beginners should not immediately perform finishing work. First, it is better to train under the supervision of a specialist in order to acquire the necessary skills and experience in performing such operations.

You can see the aluminum welding process in the video:

What should the device be like?

There are no particularly specific conditions for the device .
It must maintain a sufficient operating current for the selected workpiece thickness and electrode diameter. The operating voltage is set around 22-24 volts. The device must support reverse polarity mode.

A large current reserve leads to an increase in size, weight and increased energy consumption.

If your plans for welding aluminum are large and such work is planned to be carried out constantly, then it is better to immediately purchase a device that supports the TIG mode, or welding with a non-fusible electrode in an argon or helium protective atmosphere. The electrode can be made of tungsten or graphite. This semi-automatic device allows you to cook with conventional fusible rod electrodes without gas supply.

What parameters are set depending on the thickness of the metal being welded?

When setting up the welding machine, you must perform the following manipulations:

adjust the AC balance (plus or minus) . Typically, when welding aluminum, reverse polarity is used, that is, “-“;
adjust the welding current depending on the thickness of the elements being connected . The pulse current increases with increasing thickness of the parts being welded. So, for aluminum with a thickness of 1 mm, a current of 23 to 27 Amperes is used, and for welding aluminum with a thickness of 5 mm - 150-180 Amperes;
adjust arc attenuation, which also depends on the thickness of the parts : the thicker, the longer. For example, to connect aluminum with a thickness of 2 mm, it is enough to set this parameter for 3 seconds;
set up gas purging for cooling (if such a function is available).

Features of the technology

Let's look at the features of aluminum electrode welding technology. Manual arc welding of aluminum is not the most convenient process, so it is important to know and take into account some features of welding.

Selection of electrodes . First of all, you need to select the appropriate type of electrodes. The fact is that some brands have a coating intended only for working with aluminum alloys. Others are used exclusively for welding pure aluminum. Therefore, this parameter should be taken into account. Electrode manufacturers indicate the purpose of a specific brand, so you can easily choose the right one.
Surface cleanliness . When welding with electrodes, preparation of the surface of the structure is of great importance. It should be well processed so that the seam is smooth and durable.
Current _ Aluminum welding is carried out using direct current of reverse polarity. This is due to the fact that an oxide film forms on the surface of this metal. And with reverse polarity, the film is destroyed using cathode sputtering.

Chemical properties of aluminum

Aluminum is characterized by high solubility of hydrogen in liquid form with low solubility at the crystallization point. This directly affects the quality of welding work. If even a small amount of hydrogen dissolves in the weld metal, the weld may become porous , as the hydrogen will tend to escape.

Another important chemical property of aluminum is oxidation . The combination with oxygen creates aluminum oxide, which forms a kind of film on the surface of the metal. On the one hand, the oxide film reliably protects the metal from corrosion. On the other hand, it becomes an obstacle to welding work . Despite the fact that aluminum melts already at 660.3

C, melting temperature of the oxide film - 2037

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Mechanical properties of aluminum

The strength, elasticity and elongation of the weld depend on the type of alloy from which the parts are made, as well as on the composition of the electrode. The strength of the welded joint will be quite weak in cold-hardened alloys. To achieve good weld strength in heat-resistant alloys, longer heat treatment times and slow cooling are required.

IMPORTANT! Aluminum has good thermal conductivity, so it is recommended to use heat-dissipating pads when carrying out welding work. This will help preserve the remaining parts of the workpieces from shrinkage and deformation.

Use of alloying components

To improve the quality of the weld, the following alloying additives can be used in aluminum electrodes:

Manganese (Mn) - increases corrosion resistance.
Silicon (Si) - reduces the melting of aluminum, improves fluidity and weldability.
Magnesium (Mg) - gives the metal excellent weldability and good strength. When combined with silicon, it forms a heat-resistant alloy.

Electrodes OK AlMn1 (96.20) containing manganese

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Preparation of materials before welding

A distinctive feature of welding aluminum using an inverter machine in arc mode is that it will not be possible to use metal and electrodes without preliminary preparation.

There will be a spark, of course, but nothing will come of it other than splashes of aluminum in different directions. To obtain the expected result, it is necessary to first prepare the materials to be welded and those that will be used for metal processing.

To give the electrodes the required properties, they must be preheated in an oven. At home, you can use a crucible, the main thing is not to overexpose it, induction or even gas, made of several heat-resistant bricks.

As for aluminum parts, before welding, the ends are carefully processed to remove the protective film. This will ensure high-quality adhesion to the surface of the liquid metal.

What do you need to know to make a quality seam?

To obtain strong and durable connections, you need to know and consider the following points:

products made of aluminum alloys are always coated with a layer of refractory oxides;
before starting welding, this layer should be removed by mechanical stripping or etching;
the oxide layer is quickly restored in air, so the treatment must be carried out immediately before welding;
the color of the aluminum billet practically does not change when heated, it will not be possible to monitor the temperature visually;
When heated, the strength of the product decreases, this can lead to the appearance of microdefects during crystallization.

Taking these features into account allows you to avoid common mistakes when you need to weld aluminum blanks at home.

Difficulties of the process

Let's look at the complexities of the electrode welding process on aluminum. The difficulty of manual welding of aluminum structures is largely due to the properties of this metal. Below are examples of the main problems that may arise during the welding process.

High metal fluidity . Molten aluminum is difficult to control. With significant overheating, the behavior of the metal becomes somewhat unpredictable. The melt can destroy the layer of solid metal underneath and flow out through the crack. To solve this problem, it is recommended to use ceramic or refractory steel gaskets .
Oxidability of aluminum . The main problem of aluminum products. Combining with oxygen, metal molecules form a dense oxide film. It is stronger than the metal itself and melts only at very high temperatures. Another disadvantage is that the film is a dielectric, so it is difficult to ignite an arc. To solve this problem, you need to thoroughly clean the metal working surface before welding .
High coefficient of linear expansion. Aluminum is quite fragile and has low elasticity. When the metal is very hot, the welding zone puts pressure on the rest of the structure, which can cause cracks or deformation of flat surfaces. To avoid this, you need control welding temperature. Better yet, preheat the part to 200-250
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When the weld metal hardens, it can crystallize and hot cracks appear . Therefore, it is advisable to add a special filler material. This is especially necessary in cases where several seams are located at a short distance from each other.

Useful video

Watch the video where the craftsman argues that welding aluminum with an electrode is not the best solution and demonstrates the process clearly, with explanations.

How to cook correctly: technique, stages and nuances

Now let's figure out how to weld aluminum structures using conventional coated electrodes, and what is required for this.

First stage: preparatory

Before starting welding, it is necessary to carry out preparatory work to clean the surface from dirt and oxide film. This is necessary in order to ensure good weldability of the metal and the formation of a high-quality seam. Sequencing:

Pre-cleaning . Any detergent + stiff brush. The metal is then washed with clean cold water.
Then the surface needs to be degreased . Organic solvents are suitable for this: white spirit, acetone, etc.
If the part is small, it You can put it in an alkaline bath for a few minutes. The solution temperature must be greater than 60
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After this, the surface must be sanded with a wire brush . Do not use abrasive agents, as particles of the working layer may remain on the surface.
The metal is then washed with a solvent . It cannot be wiped off, must dry on its own.

Video

In the next video, the master welds a bicycle stand with Zeller-480 electrodes.

NOTE! It is recommended to calcinate aluminum electrodes before use. The optimal calcination mode is 2 hours at a temperature of +200

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Welding techniques and nuances

When welding with electrodes, you need to use direct current of reverse polarity . The current strength depends on the thickness of the electrode. It is calculated as follows: per 1 mm of electrode there should be a current of 20-25 amperes.

In order for the seam to be of high quality, the working surface of the part should be heated to a temperature of 300-400

C. This will help prevent hot cracking and also reduce the risk of material deformation.

The electrode must be held vertically, but can be tilted slightly . The end of the rod should be moved in the direction of the seam . It is recommended to weld in one pass on a short arc, without making transverse movements.

If the arc breaks the slag crust must be removed from the crater on the working surface and from the end of the electrode . Then you can continue working. After welding is completed, the resulting seam should be cleaned of slag formations and washed with water .

IMPORTANT! Aluminum electrodes melt 2-3 times faster than conventional ones. Therefore, when we weld aluminum with electrodes, it is recommended to weld with one electrode continuously until it completely melts.

Find out more about electrodes for aluminum here. Where to buy electrodes for aluminum.

Covered welding technique

Welding of aluminum parts with an inverter is carried out using a current of reverse polarity, in the lower welding position . This is due to the high fluidity of the melt and the need to maintain a high speed of electrode movement

The electrode should be brought perpendicular to the seam line or with a slight tilt back. The trajectory of movement is straight, without transverse swings.

Operating modes for welding aluminum parts of different thicknesses.

The substances contained in the coating increase the resistance of the weld pool material to the passage of current, which complicates the re-ignition of the electric arc.

If the arc goes out, you should remove the slag layer from the crater and from the tip of the rod, and step back 1 cm . The remainder of the seam and the crater must be welded again to avoid porosity.

Upon completion of the seam, its surface is cleaned of slag and washed with water.