What is the name of the aluminum based alloy?

Pipe D16T: standard and material features

By what standards are thin-walled and thick-walled pipes D16t produced? What material is it made from? How does this material differ from alternative solutions? Let's figure it out.

Meet the hero of our today's material.

Raw materials

First, let's separate the flies from the cutlets. D16t is a marking not of the pipe itself, but of the alloy from which it is made. Like all aluminum alloys, ours has a low density (about 2800 kg/m3).

The main disadvantage of aluminum is its low mechanical strength, which is largely offset by the addition of other elements of the periodic table.

Compound

According to GOST 4784-97, alloy D16 has the following composition:

Please note: the amount of aluminum in the alloy is approximate. This metal is the base; Under certain conditions, the upper content limit indicated in the table may be exceeded.

So, the main components of the alloy are aluminum and copper.

What characteristics does such a composition provide?

• D16 is noticeably harder than pure aluminum. However, like all duralumin alloys.
• Strength is fully maintained in the range of up to 250 degrees Celsius. Actually, in the range of 120 - 250C this alloy has no equal among all types of duralumin.
• The upper limit of short-term heating is about 500C.

Post-processing

Perhaps the reader noticed that the name of the alloy - D16 - differs from the one in the title of the article D16t in the absence of a letter at the end.

Blanks of alloys D16 and D16t.

It stands for post-processing method. The following options are possible:

Useful: in the price lists of manufacturers you can find markings like D16TA. This designates an alloy that has undergone hardening, natural aging and (after forming the part) plating.

Terminology

Some terms may need clarification.

• Annealing is heating to the recrystallization temperature (in our case, approximately 500C) followed by slow cooling. Without going into the physics of the process, we note that annealing gives metals increased ductility and toughness, and at the same time relieves internal stresses in metal structures.
• With rapid cooling from the recrystallization temperature to room temperature and below, the physical properties of the metal change in the other direction: on the contrary, it becomes extremely hard. The corresponding process is called hardening.
• Plating is the application of a layer of pure aluminum to the surface of the alloy. The fact is that it has greater corrosion resistance than many of its alloys; plating performs a protective function.

Broken cladding layer on a 5-ruble coin.

But the process of aging the alloy is so interesting that we will devote a separate section to getting to know it.

Aging

At the beginning of the 20th century (more precisely, a decade before the First World War, in 1903), the German materials scientist Alfred Wilm, an employee of the metallurgical factory Dürener Metallwerke AG, discovered an unexpected phenomenon while studying the properties of aluminum.

An alloy of 96% aluminum with 4% copper, after being quenched, like many other metals, quite predictably became harder and stronger. However, the process did not stop when the alloy reached room temperature: at 20C in the next 4-5 days, the metal continued to gain strength without losing its ductility.

The alloy was called duralumin (in honor of the German city of Duren, where its industrial production began in 1909), and its composition and heat treatment technology were quickly classified: at first it was widely used for the construction of frames for military airships.

The photo shows the German airship Graf Zeppelin. Duralumin was used to construct a rigid frame that made the aircraft resistant to gusts of wind.

However, the awl cannot be hidden in a bag: by 1920, duralumin had become the main material in aircraft construction around the world. During the experiments, another interesting property of the alloy was revealed: the process of gaining strength can be sharply accelerated by heating it after hardening to 188 - 193 degrees.

In this case, maximum strength was achieved in 11 - 13 hours, which, of course, from the point of view of manufacturability, looked much more advantageous.

How strong is the D16t alloy compared to pure aluminum? Let's compare their resistance to compressive loads: aluminum can withstand 7-8 kg/mm2, and duralumin 45.

Hardness, electrical and thermal conductivity of aluminum alloys.

There are a few more things to know about rafting.

GOST 18482-79

Actually, let's get back to the pipes. They must be produced in accordance with GOST 18482-79 “Pipes pressed from aluminum and its alloys.”

Let's study the main provisions of the document:

• Pipes can be either round or shaped.

Several types of duralumin profiles.

• In terms of wall thickness, the standard provides for division only into thin-walled (wall up to 5 mm) and thick-walled (over 5 mm).
• The outer diameter for a round section, according to the assortment table contained in the standard, can vary from 18 to 300 millimeters . Maximum permissible deviations from the nominal size increase with increasing diameter and take values ​​from 0.5 to 2.8 mm up or down.
• The wall thickness can reach 93.116 millimeters with a 300 mm diameter.

Please note: the assortment table is not an immutable canon. Additional sizes may be introduced upon agreement with the supplier; In this case, tolerances are taken as for the smaller of the nearest diameters.

• The length of the products is from 1 to 6 meters: unmeasured, measured or multiple of measured . In the latter case, the instruction common to most similar standards applies: a 5-mm allowance is made for each cut. Interestingly, pipes made of softer alloys can be supplied in coils up to 15 kilometers long.

The hardness of the D16t alloy allows pipes to be supplied only in straight sections.

• Products with a wall thickness of over 10 mm and an outer diameter of 100 mm or more must not have burrs on their outer surface.

Conclusion

We will consider our acquaintance with the new material successful. We hope that it will be useful to the reader (see also the article “Pipe for underfloor heating: how to choose the optimal type and install it correctly”).

As always, the video in this article will offer additional information. Good luck!

Source: https://remstroymast.ru/tryba-d16t-standart-i-osobennosti-materiala.html

What is the name of the aluminum-copper alloy? Production of metal alloys based on copper and aluminum

Aluminum is considered one of the most common metals on Earth. It is also called “flying metal”. Although it does not occur in nature in its pure form, it can be found in many minerals. And the most common alloy, which is used to produce many parts and structures, is duralumin (duralumin).

It was invented by the German scientist Alfred Wilm, who worked at the Dürener Metallwerke AG plant (Düren). He determined that an alloy of aluminum and copper has much better characteristics than the metal itself in its pure form.

Group of high-strength alloys

In fact, duralumin is a whole group of alloys in which the main component is aluminum, and its alloying elements are copper, zinc, manganese, and magnesium. But in general, their characteristics are determined not only by their composition, but also by the method of heat treatment. In 1903, it was discovered for the first time that an aluminum-copper alloy becomes even stronger and harder as it ages.

As it turned out later, this is explained by the fact that when, after hardening, the metal is kept at room temperature for several days, its supersaturated solid solution disintegrates, and this, in turn, is accompanied by strengthening of the material.

The aging process and return to a previous state

As mentioned earlier, metal aging is an important process that is caused by structural transformations that cause changes in physical and mechanical properties. It can be natural or artificial. In the first case, the alloy is kept for several days at room temperature.

With artificial aging, the processing time is reduced, but the temperature increases. In order to return the alloy to its previous state, it must be heated to 270 degrees for a few seconds and then quickly cooled.

Aluminum production

In order to produce an alloy of aluminum and copper, you need high-tech equipment and, of course, the metal itself. It is mined from bauxite. This is a rock that needs to be crushed, water added to it and treated with steam under high pressure. In this way, silicon is separated from alumina. Then the thick mass is placed in a special bath with straightened cryolite. The contents are heated to 950 °C and an electric current of 400 kA is passed through it.

This allows the bond between the oxygen and aluminum atoms to be broken. As a result, the latter settles to the bottom as liquid metal. This is how castings are made from liquid aluminum. Now the metal is completely ready for machining. However, in order to increase its strength, it is necessary to add alloying elements to it and thus obtain a high-quality aluminum-copper alloy.

Production of duralumin

In total, all aluminum alloys are divided into two groups: cast and wrought. The process of their production depends on what type should be obtained in the end. In addition, the manufacturing method also depends on the required characteristics.

To produce duralumin, aluminum ingots are melted in an electric furnace. Interestingly, this is one of the few metals that can be transferred from solid to liquid and vice versa many times. This will not affect its performance. Copper and other alloying elements such as manganese, iron, and magnesium are added to the molten aluminum in turn. It is very important to observe the percentage ratio: 93% aluminum, 5% copper, the remaining 2% comes from other alloying elements.

Hardening and annealing of duralumin

The hardening process is mandatory for such an alloy. The holding time for small parts is only a few minutes, and the temperature is about 500 °C. Immediately after the procedure, duralumin becomes soft and viscous.

It is easy to deform and process. After some time, the alloy hardens and its mechanical properties increase. If the temperature threshold is exceeded, oxidation occurs and the material loses its characteristics.

After hardening, it must be cooled slowly in cool water.

So, you already know what the aluminum-copper alloy is called. It can often be deformed: cold rolled, drawn, forged. In this case, so-called hardening occurs. This is a process during which dislocations move and multiply in the metal structure.

As a result, the alloy itself changes its structure, becoming harder and more durable. This reduces its ductility and toughness. To ensure that deformations occur more easily and cold hardening does not destroy the metal, annealing is used.

To do this, the alloy is heated to 350 °C and then cooled in air.

Alloy phase diagram (aluminum and copper)

In order to most clearly describe the interaction of duralumin components in the solid and liquid state, as well as explain the nature of the change in the properties of the alloy, a state diagram is used.

It shows that the highest solubility of Cu in the alloy with aluminum is observed at a temperature of 548 ° C and at the same time it is 5.7%. As the temperature increases, it will increase, and as it decreases, it will decrease. Minimum solubility (0.5%) will be observed at room temperature. If duralumin is hardened above 400 °C, it will become a solid homogeneous solution - α.

During this process, the solid solution will decompose. An alloy of aluminum and copper, the formula of which is CuAl2, behaves very unusually. The process is accompanied by the release of excess phase A1. This decay occurs over a long period of time. This is the natural aging that we mentioned earlier.

Alloy properties

Alloying a metal with certain elements can improve its characteristics. Do you remember the name of the aluminum-copper alloy? What properties does it have?

Aluminum itself is very light, soft and completely fragile. It is soluble in weakly concentrated alkalis and acids. By adding copper and magnesium to aluminum, you can get a fairly strong alloy. Its performance parameters are quite easy to improve - you just need to leave it to sit at room temperature. Thus, the aging effect increases the strength of duralumin, as we discussed above.

Aluminum itself is quite light. A small percentage of copper does not make the alloy heavier. Another positive characteristic is the ability to remelt the alloy many times. At the same time, it will not lose its properties. The only thing that is necessary is to let it “rest” for a couple of days after casting.

The disadvantage of duralumin is its low corrosion resistance. Therefore, most often such material is coated with a pure layer of aluminum or painted with varnishes and paints.

Aluminum alloys and their applications

For the first time, duralumin was used to make airships. The lightness and strength of this material made it possible to create an excellent aircraft. For this purpose, the D16t brand was used. Currently, alloys with aluminum, zinc, copper and other alloying elements are widely used in astronautics, aviation and other areas of mechanical engineering.

For example, the use of duralumin in the manufacture of a car can significantly reduce its weight and cost, but at the same time it will be quite durable.

In general, it can be noted that the range of this alloy is quite wide: pipes, wires, sheets, tapes, rods and cast parts of various shapes. D16t is still considered one of the most popular and widespread brands. The small “t” at the end of the marking means that the alloy is hardened and has naturally aged. It is used:

• In the designs of spacecraft, ships and aircraft.
• For the manufacture of various parts for machine tools and machines.
• For the production of street signs, road signs.

Everyone should know the name of the alloy of aluminum and copper. Dural is also used in the oil industry. Thus, special pipes made from it can ensure the operation of a well for 6-7 years.

It’s easy to remember what the alloy of aluminum and copper is called. So, we told you what properties it has and where it is used. It can easily replace rolled steel, especially if it is necessary to make the structure lightweight.

Source: https://autogear.ru/article/358/652/kak-nazyivaetsya-splav-alyuminiya-s-medyu-proizvodstvo-splavov-metallov-na-osnove-medi-i-alyuminiya/