Specific weight of steel. Specific heat of steel

Steel is considered an alloy of iron with other chemical compounds. Among the components included in the composition, there is carbon in the amount of 2.14%. Due to its presence, iron alloys acquire their strength. The specific gravity of the steel is equal to 75500-77500 N / m³. The alloy may sometimes contain alloying elements. The specific heat capacity of steel at 20 ° C is measured at 460 J / (kg * ° C), or 110 cal / (kg * ° C).

Classification

There are various parameters, according to which the material under consideration is characterized. For example, steel can be instrumental and structural. High-speed alloy is considered one of the types of instrumental. There are also differences in accordance with the chemical composition. Depending on what elements are present in the alloy, the alloy and carbon are divided. The classification according to the level of carbon concentration has also been adopted. So, there are three types of alloys:

1. Low carbon. In it, the carbon content is up to 0.25%.

2. Medium-carbon steel. In this carbon alloy, about 0.25-0.6%.

3. High-carbon steel. In this alloy, about 0.6-2% of carbon is present.

Similarly, alloyed steel is classified according to the percentage content of alloying elements:

1. Low alloy steel contains up to 4%.

2. In the medium-alloy alloy, up to 11% is present.

3. High-alloy steel. It contains more than 11%.

Steel is produced by various methods and using special technologies. Depending on this or that method, the alloy contains different metallic inclusions. This index affects the specific gravity of steel. Classifying alloys by the number of impurities, distinguish:

1. Mixtures of ordinary quality.

2. Qualitative.

3. High-quality.

4. Particularly qualitative.

There is also a classification in accordance with the structural composition of the material. For example, ferritic, bainitic, austenitic, perlite and martensitic alloys are produced. Undoubtedly, the structural composition also affects the specific gravity of steel. Alloys are also divided into two-phase and multiphase. This depends on the presence of phases in the structure. Also, alloys are classified by the nature of solidification and the degree of deoxidation. So, there is a calm, half-quiet and boiling steel.

Methods of steel production

Cast iron is used as a raw material for steelmaking. The presence of a large amount of carbon, phosphorus and sulfur in its composition makes it brittle and brittle. For the processing of one material in another, it is necessary to reduce the content of these substances to the desired concentration. At the same time, the specific gravity of steel and its properties will change. This or that method of production of alloys assumes different ways of oxidation of carbon in cast iron. Most commonly used are:

1. Marten's method of steel smelting. It should be noted that this option recently competes poorly with other methods.

2. The converter method. Today, most types of steel products are produced using this technology.

3. Electrothermal - one of the advanced technological methods of steel production. As a result, the material produced is of very high quality.

The converter method

Using this technological method, the excess of pig iron, phosphorus and sulfur is oxidized with oxygen. A pressure purge is carried out through the molten material in a special furnace. It's called the converter. This oven has the shape of a pear. In its inner part - lining with refractory bricks. This oven is highly mobile: it can rotate 360 degrees. The converter capacity is about 60 tons. As a rule, two types of raw materials are used for lining:

1. Dinas - it contains SiO2, which has acid properties.

2. Dolomite mass - MgO and CaO. It is obtained from the dolomite material MgCO3 * CaCO3, which has the properties of bases.

Because of the different material for lining, converter furnaces are divided into Thomas and Bessemer furnaces. The blown air under pressure covers the entire area of the metal. It should be noted that the processes occurring in the furnace have a duration of no more than 20 minutes. The residence time of the material in the converter affects the heat capacity of the steel. The alloy that is produced in converter furnaces often contains a large amount of iron monoxide. That's why the material is often of poor quality.

The Marten furnace

This method of processing pig iron is obsolete. Undoubtedly, when using several backward technologies during processing, the quality of the material is significantly reduced, its technical characteristics (heat capacity of steel and others) change. The Martin furnace is a large melting bath. It is covered with a vault of refractory bricks and recuperator chambers. These compartments are designed for heating combustible gas and air. They are filled with a nozzle made of bricks (fireproof). The flow of hot gas and air is blown into the furnace through the third and fourth recuperators. And the first and the second in the meantime are heated from the furnace gases. After a sufficient increase in temperature, the entire process goes in the opposite direction.

Electrothermal method

This method has several advantages over open-hearth and converter. The electromechanical method allows to change the chemical composition of the obtained steel. At the same time, the mixture after the processing process is of a very high quality. Due to limited access of air to the electric furnace, the amount of iron monoxide is reduced. As you know, it pollutes steel with its impurities. And this, in turn, has a significant impact on its quality. In the electric furnace, the temperature does not drop below 2000 ° C. Thus, harmful impurities such as sulfur and phosphorus are completely removed from the cast iron composition.

Method of operation of the furnace

Electrothermal furnaces, due to their high temperature, allow alloying of steel with the help of refractory metals. They include, in particular, tungsten and molybdenum. The electric steelmaking method allows to obtain a high-quality mixture: specific heat of steel, as well as its qualitative characteristics - at the highest level. But, unfortunately, these furnaces consume a large amount of electrical energy (up to 800 kW per hour per ton of raw materials). The capacity of electric furnaces can range from 500 kg to 360 tons. The aggregates use a conventional lining. The structure of the charge may amount to 90% of iron scrap and 10% of pig iron. Sometimes the proportions of raw materials can be different. Lime, which is added to the charge, plays the role of flux. The main chemical processes in electric arc furnaces are not very different from open-hearth furnaces.

Specific gravity

The currents of the industrial frequency are used to induction heating the metal. Due to the large mass of the core, this effect is quite sufficient. For the melting of steel with a mass of up to 100 tons, a current of 50 Hz is sufficient. It should be said that some parameters for different types of the same raw material may coincide. For example, corrosion, heat-resistant and stainless steel have a specific gravity 7.9 g / cm ³ . This indicator is directly related to the weight of the finished product at the output. That is, what it is more, the product, respectively, is heavier. And the specific gravity of galvanized steel is also about 7.9 g / cm ³ . There may be a slight difference depending on the type. But the specific gravity of sheet steel is 7.85 g / cm ³ . As you can see, the indicator is somewhat lower, so the material is also easier. It should be assumed that the specific weight of pig iron and steel is different. The alloy output is higher, as a rule. This is more due to the fact that in the process of processing, in spite of the fact that some components are eliminated from the raw material, additional elements are added to the mixture. They influence the parameters of the output product. Different types of cast iron have their specific gravity (in g / cm ³ ):

- white - 7.5 ± 0.2;

- gray - 7.1 ± 0.2;

- malleable - 7.5 ± 0.2.

Calculation

The relationship between the volume of an alloy and its mass is characteristic only of a particular substance. In addition, this parameter is permanent. Using a special formula, one can know the density of matter. It has a direct relation to the calculation of the specific gravity of the alloy. That's how it looks.

The specific weight of the metal is assigned in the formula as γ. It is equal to the ratio of P - the weight of a homogeneous body - to the volume of the connection. And calculated by the following formula: γ = P / V.

It works only when the metal has a completely dense state, non-porous.

Conclusion

New technologies that are used in heavy industry, in many respects differ from those that were applied at the initial stage of development of this industry. Thanks to scientific progress, the modern metal industry produces a huge number of variations of alloys. The specific weight of the compounds affects the choice of a particular type of raw material, which will be used in the production. If you take three different metals: iron, brass and aluminum with the same volume - then all will have different masses. Therefore, when choosing a particular metal, it must take into account, among other parameters, its specific weight.