At present, almost all industries use aluminum alloy. It is used everywhere, from the production of dishes, and to the manufacture of spare parts for cars.
Silumin
It is worth starting with the fact that there are several different alloys in which aluminum is used. However, this one is considered the most popular among others. Silumin is the next step after aluminum. Get it using a silicon alloy added to this chemical element. The combination of these two elements provides the resulting alloy with increased hardness, as well as increased resistance to wear of parts obtained from the alloy.
The silicon content in such alloys ranges from 4 to 22%. It is also worth saying that some more elements may be added. These include copper, zinc, titanium, iron or calcium. It is also known that silumin is included in the composition of silumin.
Silumin properties
It is important that silumin is all alloys that were obtained on the basis of silicon and aluminum, but it must be understood that not all final materials have the same properties. You need to know that with an increase in the percentage of silicon content, the final strength of the material increases, but its fragility also increases. The main advantages that can be distinguished from this alloy include:
- High strength.
- Low physical weight.
- High wear resistance of the material.
- Resistance also to corrosion.
- One of the important advantages is the price of silumin, which is considered quite low. Let's say kitchen utensils from this material cost from 250 r. up to 2000-3000 p.
All of these advantages combined and were able to ensure the high popularity of this material.
This material has only one drawback - it is its increased fragility. If we talk about mechanical effects, then silumin is able to withstand high loads, but if, for example, a product from this alloy is dropped, then it will most likely crack. It is also worth noting that the melting point of silumin is not too high - only 580 degrees Celsius.
Marking
Since silumin is an alloy of aluminum and silicon, and also just one of its varieties, a special marking has been developed that allows you to quickly and easily determine the percentage of components, as well as which particular chemical elements were used in the manufacture of the alloy. In order to mark the silumin alloy, use alphanumeric designations. For example, AK12 or AK9TS7. The first letter always indicates the aluminum content in the alloy, and the second indicates the silicon content. The numbers indicate exactly what percentage of this chemical element is in silumin. In this case, it is 12%. Since other elements can be added, their letter is also indicated. The second example shows the marking of aluminum - A, silicon - K 9% and zinc - C 7%.
It is also important to note that the alloy has a high fluidity in the molten state, as well as good weldability. Given that the melting point of silumin is only 580 degrees Celsius, this can be attributed to the list of material advantages.
Types of silumin
Most often they say that silumin is an alloy of aluminum and silicon. However, this is not a true statement. Alloys are of such a name, in which the content of such an element as silicon is in the region of 12–13%. Such a group of alloys is commonly called eutectic, normal or ordinary silumin. However, there is another classification of this material.
- The first type of alloy is called pre-eutectic. A characteristic feature of this group is that the silicon content in the percentage ratio of only 4 to 10% of the total. In addition, elements such as magnesium, manganese or copper can be added.
- The group of wear-resistant silumins - the silicon content rises to 20% of the total amount of alloy.
- To perform specific tasks, special alloys of silumins are made, for example, zinc.
Properties of normal silumins
The first group of aluminum silumins is eutectic. Their strength parameters are quite small, but the advantage of this type is different. It has excellent casting parameters. Materials from such an alloy are used in the molding of thin products, which in the future will be used in an environment of increased vibration or under the influence of shock loads.
It is also important to note that when casting this group of alloys, such requirements as elongation of the microstructure can be presented to it. To fulfill this requirement, it is necessary to modify silumin with sodium during the operation of casting in a chill mold or in a mold.
It is also important to note that only those that are characterized by a high purity of the composition are highly resistant to the effect of an aggressive environment on the alloy. In other words, in such materials there should be a minimum content of various impurities, such as iron and others.
Alloy groups
There are several groups into which silumin is divided. This separation is carried out by the use of this material for various purposes.
The eutectic silumin, which is marked AK12, that is, only 12% of the silicon content, is also not hardened by heat treatment and does not form shrinkage strength, it is recommended to use it for the manufacture of sealed parts of devices or units of low loading.
As an example of a pre-eutectic silumin, we can take the AK9ch alloy. For its manufacture, quenching is already used at a temperature of 530 degrees with a holding time of 2 to 6 hours. After that, there is a process of cooling the material in hot water and activate the aging process at a temperature of 175 degrees, which lasts for 15 hours. The use of silumin of this group is carried out for the manufacture of loaded and bulky parts.
The third group of alloys is a highly alloyed hypereutectic silumin, the marking of which is AK21M2. This material belongs to the piston group of alloys. This material is intended to work in an environment with elevated temperatures, as it is distinguished by increased heat resistance and a high coefficient of wear resistance.
Repairs
Since it may happen that cracks or breaks appear on the parts of this alloy, there is the possibility of repair work. Most often, a special substance is used for carrying out this type of work - epoxy glue. However, in the event that the part is to be operated in an environment with increased loads, it is best to use welding. However, it is necessary to take into account the composition of the alloy, since not all of them are able to withstand the temperature of the welding machine, some of them can simply melt.
Welding
Repairing silumin at home using argon arc welding is considered the easiest way. However, everyone recognizes that the best solution for repairing parts will still be to turn to professionals, but self-welding is also quite real. It is important to note that the work of argon-arc welding should be carried out in an inert gas environment.
Most often, argon gas is used directly to achieve this, but in some cases it is possible to use a mixture of argon with helium. It is also important to note that after welding work on the repair of parts from silumin, all welding seams must be processed. After this procedure, the seams will be almost invisible.