The bicycle frame is the supporting part, since all the main components are attached to it. 70% of the load falls on the frame, which is why the structure must be made of high-quality materials.
For many owners, the main criterion is the weight of the product; the smaller it is, the more convenient it is to operate the product. Weight directly depends on the material, so you should choose a bike based on this criterion, taking into account the pros and cons of each.
Which profile to choose: aluminum or galvanized?
Both materials: aluminum and galvanized steel are actively used for the installation of ventilated facades. Both have their strengths and their followers. Let's consider the advantages of each facade profile for the construction of ventilated facades.
The facade profile is galvanized.
The low cost of galvanized facade profiles is its main advantage. But, if you consider what difficulties you will encounter during the installation process and during further operation, then this advantage no longer seems so significant.
Steel coated with a thin layer of zinc is protected from the aggressive effects of the external environment, but zinc itself is also susceptible to corrosion, just to a much lesser extent. The “white” rust covering it must be treated. For these purposes, the galvanized profile is painted and it becomes truly protected. Only during installation is the galvanized facade profile cut to size directly on the construction site using a circular saw (grinder), and nothing prevents rust from appearing at the cut site.
Aluminum facade profile.
The higher cost of aluminum facade profiles is compensated by the convenience and ease of installation, as well as its durability and safety.
The aluminum façade profile is excellently protected from corrosion. Under the influence of oxygen, the surface of aluminum is covered with a strong, stable oxide film (passivated). Aluminum oxide creates a chemically inert protective layer that protects the metal from corrosion, that is, from the process of destruction of metals as a result of chemical or electrochemical action.
Fire resistance of façade aluminum and galvanized profiles.
Melting point, 0 C
Aluminum profile – 640
But during a fire, the temperature inside the cladding remains no more than 420 0 C!
According to GOST 31251-2008, the structure with cladding undergoes fire tests. If the integrity of the cladding is compromised, then the system, regardless of the profile material, will not pass the test.
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Two hardening mechanisms
There are two mechanisms for strengthening aluminum alloys, which can complement each other:
- strain hardening (hardening) and
- thermal hardening (aging).
The starting point for assessing the degree of increase in the strength of aluminum alloys as a result of deformation or thermal hardening is usually the values of the strength characteristics of the alloy in the “soft” state, which is its state after complete annealing.
Even in a state of complete annealing, the strength of any alloy increases with increasing content of interstitial atoms in the aluminum solid solution, that is, increasing the content of alloying elements. Examples are the alloys of the Al-Mg and Al-Mg-Mn systems, which are shown by the circles with plus signs (+) at the bottom of the diagram in Figure 1.
Galvanized spillways
The low price of the drainage system is its only advantage over aluminum. Availability is offset by low corrosion resistance and the complexity of processing the elements.
A layer of zinc covered with paint and varnish material on top protects the metal well from corrosion. However, the appearance of scratches on the surface of pipes/gutters is a reason to sound the alarm. The combination of zinc and paintwork, unlike aluminum with powder paint, does not form a protective oxide film when interacting with oxygen. Therefore, if a galvanized drainage system is damaged, it rusts and becomes unusable within 3-5 years.
Rusting U-shaped galvanized drain on the facade of a building
The second vulnerability factor of galvanizing—the difficulty of processing—is expressed in the following. As a rule, gutters and pipes are cut directly on objects using an angle grinder (grinder). If the cut area is not treated with anything, rust will quickly appear here. There are two ways to avoid this:
Make gutters exactly to the dimensions of the roof slopes so that they do not have to be cut.
Treat the edges of the elements with special compounds or re-paint them.
In both cases, the buyer spends more time and money preparing the system for installation.
Initial check
Every scrap metal acceptor needs to know the differences between aluminum and other metals. Many popular household items are made from it. Therefore, the surrender of aluminum items is a common and widespread occurrence.
The first feature is that aluminum is lightweight. Compared to many other metals. Plus, it has a low density. As a result, sometimes it is enough to use force to evaluate the material’s resistance to deformation.
The next fact is that aluminum products have a silvery-white hue. Therefore, if the item is not painted, it can be visually confirmed in this way. Application of magnet
If previous checks are in doubt, and there is no way to verify it chemically, then you can use a magnet.
Steel, cast iron, iron will react and become magnetized. Aluminum - no. Yes, there is also copper. But it is characterized by a completely different color. Therefore, it is simply impossible to confuse aluminum and copper.
This method has only one drawback - it will not determine the purity of the composition. That is, it is aluminum or an alloy based on it.
Aluminum drain LINKOR in Moscow
Aluminum construction is more expensive than galvanized construction, but it is superior in a number of ways:
Powder paint is applied over the aluminum drain. The layer thickness is 70 microns, which is 200-300% more than classic paintwork for galvanized systems. This contributes to improved noise absorption from raindrops and a more comfortable pastime for guests.
When exposed to strong water flows, aluminum gutters make almost no noise
If you are planning to buy metal roof gutters in Moscow or the region, take a closer look at aluminum structures from LINKOR. We will deliver pipes, gutters, fittings and components in standard colors within 3 days, and also carry out professional installation of the system.
For any questions, call the number. The office is open daily from 9 a.m. to 9 p.m. Applications on the website are accepted around the clock.
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Checking for density
This is exactly the case when school knowledge in physics, mathematics and chemistry will be useful in real life. Aluminum can indeed be defined by its density. How to do it:
- Take a graduated cylinder and fill it with water.
- We place a piece of the material being tested in it.
- We calculate the volume - the object will displace some of the water from the graduated cylinder, which will indicate the level on the scale when the material is removed.
- Weighs the piece being tested.
- Now we apply the formula: divide the mass by the volume.
If the result is close to 2.7 grams per milliliter, then we are definitely looking at aluminum.
Difference between steel and aluminum system
1. Steel has a lower coefficient of thermal expansion compared to aluminum. With a temperature difference from –20 to +50 degrees, a stainless 3-meter guide lengthens by 2mm, while an aluminum one by 5-6mm. Therefore, aluminum systems provide a number of movable joints and thermal seams. In steel systems, all connections are fixed, simpler and more reliable. The system elements operate in the zone of elastic deformations.
2. In a steel system, all brackets are load-bearing. Therefore, the weight of the cladding is evenly distributed over all brackets on the guide (in a double-circuit system - across the array of brackets). All fastening points are rigid, using blind rivets or self-tapping screws. Let us remind you that in aluminum facade systems the brackets are necessarily divided into load-bearing and wind-bearing ones. Moreover, the entire weight of the 3-meter guide with cladding must be carried by one supporting bracket.
3. The rest - work only for wind loads. For movable fastening of the guide to the wind bracket, oblong holes are provided in the latter. To create a movable connection, it is necessary to use blind rivets (not self-tapping screws!). In addition, the rivet attachment point should vary depending on the ambient temperature at which installation takes place.
Strength
Black steel as a material is quite strong, but is susceptible to corrosion. Powder coating only saves you from rust for a while. Stainless steel and aluminum will last much longer, and the building will look much more modern. Provided, of course, that the stainless steel is of proper quality, because lately manufacturers have managed to make stainless steel that even scrap metal points do not accept, because there is practically no metal in it (I don’t know what they mix in there). Because of this, of course, the strength of the pipe and its service life suffer greatly.
Galvanized spillways
The low price of the drainage system is its only advantage over aluminum. Availability is offset by low corrosion resistance and the complexity of processing the elements.
A layer of zinc covered with paint and varnish material on top protects the metal well from corrosion. However, the appearance of scratches on the surface of pipes/gutters is a reason to sound the alarm. The combination of zinc and paintwork, unlike aluminum with powder paint, does not form a protective oxide film when interacting with oxygen. Therefore, if a galvanized drainage system is damaged, it rusts and becomes unusable within 3-5 years.
Rusting U-shaped galvanized drain on the facade of a building
The second vulnerability factor of galvanizing—the difficulty of processing—is expressed in the following. As a rule, gutters and pipes are cut directly on objects using an angle grinder (grinder). If the cut area is not treated with anything, rust will quickly appear here. There are two ways to avoid this:
Production process
The technological process for producing this metal includes three stages:
- Obtaining alumina from primary raw materials (aluminium-containing ores).
- Creation of technical aluminum from the resulting alumina.
- The process of maximum metal purification.
Aluminum oxide is produced from alumina by electrolysis. The compound must be as pure as possible, since at this stage of its preparation it is very problematic to get rid of unnecessary impurities.
To obtain aluminum with a purity close to unity, it is necessary to organize several workshops for its processing, each of which will be responsible for a certain stage of production. That is why pure metal has a fairly high price, reaching up to $1,700 per 1 ton (1,000 kg of aluminum).
Aluminum drain LINKOR in Moscow
Aluminum construction is more expensive than galvanized construction, but it is superior in a number of ways:
Powder paint is applied over the aluminum drain. The layer thickness is 70 microns, which is 200-300% more than classic paintwork for galvanized systems. This contributes to improved noise absorption from raindrops and a more comfortable pastime for guests.
When exposed to strong water flows, aluminum gutters make almost no noise
If you are planning to buy metal roof gutters in Moscow or the region, take a closer look at aluminum structures from LINKOR. We will deliver pipes, gutters, fittings and components in standard colors within 3 days, and also carry out professional installation of the system.
For any questions, call the number. The office is open daily from 9 a.m. to 9 p.m. Applications on the website are accepted around the clock.
Brass.
Alloy of copper and zinc. Different ratios of these two components make it possible to obtain alloys with different properties. If the zinc content is from 5 to 20%, brass is called red, and yellow if the zinc content is 20-36%
These alloys are malleable and have a fairly low melting point. Externally, brass resembles gold, so it is often used in applied arts and decoration. Furniture fittings, locks, decorative elements. Musical instruments are made from brass. It is also used in the military industry.
Aluminum is a silvery-white metal, the 13th element of the periodic table. Incredible but true: aluminum is the most abundant metal on Earth, accounting for more than 8% of the total mass of the earth's crust, and it is the third most abundant chemical element on our planet after oxygen and silicon.
However, aluminum is not found in nature in its pure form due to its high chemical reactivity. That's why we learned about it relatively recently. Aluminum was formally produced only in 1824, and another half a century passed before its industrial production began.
Most often in nature, aluminum is found in alum . These are minerals that combine two salts of sulfuric acid: one based on an alkali metal (lithium, sodium, potassium, rubidium or cesium), and the other based on a metal of the third group of the periodic table, mainly aluminum.
Alum is still used today in water purification, cooking, medicine, cosmetology, chemical and other industries. By the way, aluminum got its name thanks to alum, which in Latin was called alumen.
Difference between steel and aluminum system
1. Steel has a lower coefficient of thermal expansion compared to aluminum. With a temperature difference from –20 to +50 degrees, a stainless 3-meter guide lengthens by 2mm, while an aluminum one by 5-6mm. Therefore, aluminum systems provide a number of movable joints and thermal seams. In steel systems, all connections are fixed, simpler and more reliable. The system elements operate in the zone of elastic deformations.
2. In a steel system, all brackets are load-bearing. Therefore, the weight of the cladding is evenly distributed over all brackets on the guide (in a double-circuit system - across the array of brackets). All fastening points are rigid, using blind rivets or self-tapping screws. Let us remind you that in aluminum facade systems the brackets are necessarily divided into load-bearing and wind-bearing ones. Moreover, the entire weight of the 3-meter guide with cladding must be carried by one supporting bracket.
3. The rest - work only for wind loads. For movable fastening of the guide to the wind bracket, oblong holes are provided in the latter. To create a movable connection, it is necessary to use blind rivets (not self-tapping screws!). In addition, the rivet attachment point should vary depending on the ambient temperature at which installation takes place.
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Softening annealing
Recrystallization
Any increase in strength as a result of strain hardening disappears at temperatures above 250 ºC as a consequence of recrystallization and the strength of the aluminum alloy returns to the level it had in its “soft” state. Annealing below the recrystallization temperature (which depends on the chemical composition of the alloy and the degree of cold plastic deformation) results in a less dramatic loss of strength through the recovery process.
Figure 4 – Change in hardness and structure during annealing [3]
Return
This thermal softening (annealing at a temperature of 200-250 ºC) is used, for example, to obtain a “semi-solid” state for a sheet that is in a “solid” state. For a given level of strength of an aluminum alloy, the elongation will be significantly higher than for the same level of strength obtained simply by cold plastic working.
What do both products have in common?
Differences between galvanized and aluminum profiles
1. Significant difference in the melting temperature of metals. For aluminum this is 640 degrees, and for galvanized steel this figure is three times higher - 1800 degrees. However, you should not draw conclusions from this information that aluminum is flammable; this is not the case. Aluminum structures for external installation work undergo fire tests to meet safety standards and to ensure that the integrity of the cladding is not compromised in the event of a fire.
2. Ability to create complex configurations. In terms of flexibility, the aluminum profile wins, with which you can create any structure, including unusual shapes, with smooth bends. The use of steel profiles in complex architectural projects requires thorough preparation, which leads to higher installation costs.
3. Load-bearing capacity. The tensile strength of steel structures is up to 55 kg. / sq. m. Aluminum alloys can withstand loads three times less - up to 18 kg. / sq. m. But this does not mean that for the installation of a curtain wall you should choose exclusively stainless steel options. You should pay attention to the cladding material. For granite or brick, you need to prepare a stronger steel structure. But the weight of aluminum panels is small; a profile made of a similar alloy is quite capable of withstanding such a load.
What is more expensive: aluminum or stainless steel Metalworker's Guide
The heating season has ended with grief, after which the issue of changing batteries came to the fore. It’s time to retire the leaky ancient cast-iron radiators to a well-deserved rest, replacing them with something more modern.
Private developers, when installing heating, also often cannot decide on the type of radiators. After listening to salespeople in stores praising the most popular models, an ignorant buyer is at a loss.
And he still has no idea which radiators are better - aluminum or bimetallic. Perhaps let's look at this issue objectively?
The fins located on the inside can significantly increase the heat transfer area to 0.5 square meters. Radiators are made using two methods.
The extrusion method produces cheap and lightweight products that are not of the highest quality (this method is not used in Europe). Radiators made by casting will be more expensive, but more durable.
One of the types of aluminum radiators.
2. Bimetallic radiators are made from two different metals. The body, equipped with ribs, is made of aluminum alloy. Inside this housing there is a core of pipes through which coolant flows (hot water from the heating system). These pipes are made either from steel or copper (and the latter are practically never found here). Their diameter is smaller than that of aluminum models, so they are more likely to clog.
The appearance of the bimetallic radiator is very aesthetic, and the design satisfies the most sophisticated needs. All its steel components are hidden inside.
Stainless steel
Types of stainless steel such as 304 or 316 are a mixture of elements and most contain some amount of iron, which easily oxidizes to form rust. But many stainless steel alloys also contain a high percentage of chromium (at least 18%), which is even more reactive than iron. Chromium oxidizes quickly, forming a protective layer of chromium oxide on the metal surface. This oxide layer resists corrosion and at the same time prevents oxygen from reaching the underlying steel. Other alloy elements such as nickel and molybdenum increase its resistance to rust.
We recommend an effective rust remover from metal surfaces - “RzhavoMed-U”
The most reliable method for metal recognition
Knowing the specific density of elements will help you quickly determine the type of material. For example, the density index (Al) is 2.6 g/cm3; for stainless steel it is 3 times higher. The technique is effective for products with large dimensions and weight (having the correct shape).
The essence of the technique is to determine the volume of the product and calculate its specific gravity. In such cases, you cannot do without knowledge of a special formula.
You can visually familiarize yourself with the methods of comparing metals from video sources posted on Internet resources. If you look closely at the photo, you can see the differences between two identical metals.
Cink Steel
Galvanized steel takes a long time to rust, but it will rust over time. This is carbon steel, galvanized or coated with a thin layer of zinc. Zinc acts as a barrier to prevent oxygen and water from reaching the steel, so it is protected from corrosion. Even if the zinc coating is scratched, it continues to protect nearby areas of the underlying steel through cathodic protection, as well as by forming a protective coating of zinc oxide. Like aluminum, zinc is highly reactive to oxygen in the presence of moisture, and the coating prevents further oxidation of the iron in the steel.
Professional rust converter with phosphating - “RzhavoMed”
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Aluminum: characteristics, advantages, disadvantages
One of the lightest metals that are generally used in industry. Conducts heat very well and is not subject to oxygen corrosion. Aluminum is produced in several dozen types: each with its own additives that increase strength, oxidation resistance, and malleability. However, with the exception of very expensive aircraft aluminum, they all have one drawback: excessive softness. Parts made of this metal are easily deformed. That is why it is impossible to use aluminum where, during operation, the product is exposed to high pressure (water hammer in water supply systems, for example).
Aluminum's corrosion resistance is somewhat high. Yes, metal does not “rot”. But only due to the protective layer of oxide, which forms on the product in air in a matter of hours.
