Steel C235: characteristics, properties, composition

A variety of rolled products for welded metal structures are produced from carbon steel of this grade. The standards and parameters of the material are indicated in GOST 27772, which allows the use of steel c235 in the production of channels (GOST 8240), equal and unequal angles (GOST 8509 and GOST 8510), rolled sheets (GOST 19903), I-beams (GOST 8239, 26020), and also various bent profiles and corrugated sheets.

This material can be classified as universal, since it can be purged with argon, vacuumed, modified, and processed with synthetic slags. According to the state standard, marking of shaped rolled products made from steel grade C235 is carried out with brown or yellow paint.

All about steel 235

Today, the industrial steel market is very rich. And in this regard, it is very difficult to choose exactly the grade of steel that is suitable for a particular project. You have to delve into the topic, study the characteristics, consider several options at once, hoping to find the right material.

In this article, we will make life a little easier for those who are looking for steel products for their projects. We will talk about steel 235, which is very common and revered in the field of metal structures. We will try to describe as informatively as possible all the most important aspects associated with this grade of steel.

Absolutely every grade of steel has a document clearly indicating its chemical and physical characteristics, as well as the scope of application and operating requirements. Steel 235 was no exception. GOST 27772 provides a full amount of information about this brand, but first of all we are interested in only some of it.

The composition of any steel, regardless of its purpose, will contain various chemical elements designed to improve the structure of the alloy and endow the resulting steel with some properties, be it strength, ductility, resistance to external influences and much more.

Having familiarized yourself with the composition of the alloying elements of steel 235, you can determine its physical, as well as some chemical characteristics, with a small degree of error.

The 235th is characterized by the following composition:

• 0.2% carbon.
• 0.6% manganese.
• 0.05% silicon.
• 0.3% chromium.
• 0.3% nickel.
• 0.3% copper.

Negative impurities include insignificant sulfur content - 0.05%, phosphorus - 0.04% and arsenic 0.08%.

As you can see, in terms of chemical composition, steel 235 does not have outstanding properties. However, we should assure you that in the field of its application this is not necessary and, on the contrary, more pliable material will be valued higher.

St3sp5 decoding what 5 means

Each category of steel is characterized by its specific chemical composition. It largely determines the scope of application of the workpieces being created and the difficulties that arise during heat treatment.

The chemical composition of St3 steel makes it one of the most common materials that can be found on the market. It is difficult to imagine modern construction work without this metal.

The key points regarding the chemical composition are the following:

1. As previously noted, the main chemical elements are iron and carbon. The first element has a concentration of 97%, carbon is only 0.14-0.22%. It is carbon that determines the hardness index and some other physical and chemical properties of the structure.
2. The structure includes a relatively small amount of alloying elements. The main elements are chromium and nickel, the concentration of which is 0.3%. Copper is included in the composition at the same concentration.

With a large number of varieties of steel, the concentration of harmful impurities, which are phosphorus and sulfur, is strictly controlled in the one under consideration. In addition, the composition contains nitrogen in high concentrations, which accounts for about 0.1 mass.

Structural carbon semi-quiet steel ST3ps: explanation, characteristics

Among the wide range of carbon-containing steels intended for the construction of supporting structures, the most popular is an alloy of ordinary quality - St3ps steel. The fact is that this specimen does not have a description of the welding regulations, is practically not susceptible to corrosion and has tempering hardness. It is produced by passing the material through open-hearth furnaces.

Steel St3ps

Characteristics of steel 235

The main application of this steel is the construction of metal structures. That is why completely different, specific requirements are placed on it. For such structural steel, what is much more important is not strength, but ductility, resistance to loads and relative softness, which greatly simplifies its processing if necessary. More specifically, steel 235 is characterized by a yield strength ranging from 190 to 230 megapascals with an elongation at break of around 22%.

The next important indicator for any steel directly intended for use in various types of structures is its weldability. The better and easier the welding process is, the better it is, accordingly. And steel 235 is ready to please craftsmen with its unlimited weldability. This means that two parts can be joined together by a weld without preheating and then tempering to relieve stress in the metal. At the same time, the seam itself can be applied by any of the methods available to the master, and the quality of the connection will remain invariably strong.

Plastic

Plasticity makes it possible to produce products using cold rolling. The main indicators of a material indicating plasticity are relative tensile elongation (20-24%) and the size of the yield area (2.4%). This allows the use of C235 steel sheets for bending and stamping. Thick-sheet material requires preheating, which will prevent the appearance of cracks on the surface. The reason for this is that the relative strain increases as the sheet thickness increases, which leads to the formation of cracks.

As the temperature increases, the yield strength decreases, but the yield area increases. Therefore, when processing a thick sheet, it is necessary not only to heat it, but also to increase the bending radius.

Analogs

Fortunately for many, the construction steel market is not so poor in steel with similar properties and compositions. Brand 235 also has similar “twin brothers”. The closest analogue is the well-known structural steel St18Kp, VSt3Kp2 or simple St3Kp2.

Rest assured: each of these brands is quite common and is sure to be available in large quantities at any enterprise engaged in the manufacture and sale of steel products.

Chemical composition

The chemical composition of steel C235 according to heat analysis of a ladle sample must comply with the standards given in table. 1 (Table 1-2 GOST 27772-88).

Chemical composition of steel according to heat analysis of ladle sample

Note: When smelting steel from Kerch ores, the mass fraction of arsenic is no more than 0.15%.

It is allowed to treat steel with synthetic slags, vacuum degassing, blowing with argon, modifying steel with calcium and rare earth elements based on the introduction of no more than 0.02% calcium and 0.05% rare earth elements into the metal (clause 2.10 of GOST 27772-88).

It is permissible for the manufacturer not to carry out a chemical analysis of steel for the content of chromium, nickel, copper, arsenic and silicon. The required chemical composition is guaranteed by the manufacturer. In steel smelted from Kerch ores, the determination of arsenic is mandatory (clause 2.13.1 of GOST 27772-88).

The weldability of steel is guaranteed by the manufacturer (clause 2.18 of GOST 27772-88).

Mechanical properties

The mechanical properties of shaped and rolled sheets made of steel C235 in tension, impact strength, as well as bending test conditions must meet the requirements of Table 2 (Table 3-4, clause 2.7 of GOST 27772-88).

Mechanical properties of rolled steel C235

For sheet metal with a thickness of 4-8 mm, the rate of relative elongation δ5 = 24% (clause 2.21 of GOST 27772-88).

The calculated resistances in tension, compression and bending of sheet, wide-band universal and shaped rolled products made of steel grade C235 in accordance with GOST 27772–88 for steel structures of buildings and structures should be taken according to table. 3 (Table 51 Appendix 1 SNiP II -23-81)

Calculated resistance of rolled steel C235

1. The thickness of the shaped steel should be taken as the thickness of the flange (its minimum thickness is 4 mm).
2. The values ​​of the calculated resistances were obtained by dividing the standard resistances (yield strength and tensile strength according to GOST 27772–88) by the reliability factor for the material γm = 1.025 (clause 3.2 of SNiP II -23-81), rounded to 5 MPa (50 kgf/cm²) .

Products – Tekhmashholding – group of companies, official website

In the production of metal structures, C245 steel is a low-carbon grade used for building structures.

Decoding steel C245

In the designation of steel, the letter C means “construction”, the numbers 245 are the yield strength (T) in megapascals (MPa). In more conventional units σT = 24.5 kg/sq. mm.

Among other parameters characterizing the mechanical properties of steel, we note the tensile strength = 370 MPa (37 kg/sq. mm).

Analogues of steel grade C235

Carbon steel C235 according to GOST 27772-88 corresponds to the following grades of carbon steel:

• St3kp2 according to GOST 380 and GOST 535 (Appendix 1 GOST 27772-88)
• VSt3kp2 according to GOST 380-71 (Table 51b appendix 1 SNiP II -23-81)
• VSt3kp2-1 according to TU 14-1-3023–80 (Table 51b appendix 1 SNiP II -23-81)
• 18kp according to GOST 23570–79 (Table 51b appendix 1 SNiP II -23-81)
• E 235-A and Fe 360-A according to ISO 630:1995 (Appendix A GOST 380-2005)

We manufacture the following standard metal products:

Flight stairs, platforms, stepladders and their guards according to series 1.450.3-7.94.2:

• Steel flights of stairs type LGF with continuous corrugated steps
• Steel platforms type PGF with continuous corrugated flooring
• Steel staircases type LGV with lattice steps made of perforated wood
• Steel platforms of the PGV type with perforated grating
• Steel stair railings type OLG
• Steel fences for sites such as OPBG and OPTG
• Steel stepladders type SG for vertical stairs
• Steel railings type OSG for vertical stairs

Flight stairs, landings, stepladders and their railings according to series 1.450.3-3.2:

Steel stepladders for wells according to:

If you are interested in our metal structures

You can send us a message by filling out the following form:

Composition and structure

S235 steel belongs to the low-alloy group. The main component is iron. Additional components:

1. Carbon - content up to 0.2%. Due to the low content of this element, the alloy is easily machined and has high ductility. Hardness and strength indicators are reduced.
2. Manganese - no more than 0.6%. Increases strength.
3. Silicon - no more than 0.06%. Slightly increases strength, ductility, heat resistance.
4. Chromium, nickel, copper - the average amount of each component reaches 0.3%. Increases technical characteristics.
5. Sulfur, phosphorus - no more than 0.05%. Refers to harmful impurities.

Impurities have virtually no effect on the final characteristics of the metal.

Decoding steel

Steel grade C345 belongs to the group of high-strength steel for welded building metal structures. The chemical composition and strength characteristics are regulated by the state standard GOST 27772 of 1988. According to it, the “C345” marking is deciphered as follows:

• Carbon up to 0.15%. For steels, carbon is an integral component along with iron. Its main purpose is to strengthen the metal structure due to the formation of iron carbides. Hardness and strength are directly proportional to the quantitative carbon content in the composition. The other side of the coin of such alloying is a decrease in manufacturability: ductility and weldability.
• Silicon (up to 0.8%) is introduced for deoxidation. It increases the strength of steel while maintaining its toughness value. In addition, this element helps to increase C345’s resistance to scale formation and improves weldability. Alloying with silicon also has a beneficial effect on the elasticity of the alloy.
• Manganese (1.3 -1.7%), like the previous element, belongs to the group of deoxidizers. A small amount of manganese in the alloy has a positive effect on hardness and strength. It is worth noting that such an increase in mechanical characteristics does not in any way affect the ductility of the metal. In addition to all of the above, alloying with manganese gives the alloy greater resistance to impact loads.

These elements, along with iron, are basic for c345. But GOST 27772-88 also allows the inclusion of the following components:

• Nickel (up to 0.3%) increases the alloy’s resistance to corrosion, hardenability and heat resistance.
• Chromium (up to 0.3%) significantly increases the ability of steel to harden under the influence of temperature. Increases the corrosion resistance of metal due to the formation of dense chromium oxides on its surface. Makes steel more resistant to abrasive wear.
• Copper (up to 0.3%) prevents corrosion under the influence of an aggressive environment.

It’s worth mentioning right away that the content of the above elements in c345 is insignificant. For this reason, their influence on properties is not so significant.

Just like any alloy, S345 steel contains harmful impurities. Among them, the most common are sulfur (up to 0.04%), phosphorus (up to 0.035%) and arsenic (0.08%). Their penetration into steel is due to the inaccuracy of the chemical composition of the starting materials - the charge. The error in the temperature regime of the melting equipment also has a significant impact.

A discrepancy between the amount of impurities and the above standards leads to significant losses in metal strength and leads to the formation of an effect such as brittleness. An increase in phosphorus by 0.01% can reduce tensile strength by 25%. Sulfur also increases the susceptibility of steels to red brittleness, i.e., the formation of cracks during hot pressure treatment.

Characteristics and properties

1. Density - 7.85 t/m3.
2. Yield strength - up to 235 MPa.
3. Tensile elongation is about 22%.
4. The temporary strength indicator is 360 MPa.

Alloying additives change the characteristics and properties of the alloy. Silicon and copper increase the alloy's resistance to rust. The material has average resistance to oxidation. Parts can be stored in dry rooms that do not have special protection from moisture.

Steel mast (Photo: pixabay.com)

Steel production

1. Open hearth technology. Suitable for the production of high quality alloys. For smelting, special furnaces are used, into which up to 500 tons of consumable raw materials can be loaded. Using this method, scrap metal can be recycled. The maximum melt heating temperature is 2000 °C.
2. Converter technology. Allows the production of metals with a high content of impurities. The furnace can be loaded with 900 tons of consumable raw materials. The melting process is fast. The temperature rises to 1600 °C in a few minutes.
3. Electric melting technology. Suitable for smelting high quality alloy steels.

One of the methods that has lost popularity due to the advent of electric smelting technology is oxygen-converter.

1. Melting of scrap, charge, consumable raw materials. A melt is formed in a special bath, over which other technological processes will be carried out. One of the main tasks of this stage is the removal of phosphorus from the composition. To do this, the temperature increases slightly, the composition is saturated with a sufficient amount of iron oxide.
2. Boiling. At this stage, the amount of carbon in the composition decreases. Oxidation absorbs a large amount of heat. It is important to create a continuous flow of thermal energy to the bath so that the temperature regime is stable, without subsidence.
3. Metal deoxidation. In order for the material to be of high quality, it is necessary to reduce the amount of oxygen in the composition. To do this, it is necessary to convert the iron oxide oxides to bind oxygen to the components of the composition. At this stage, one of two deoxidation technologies can be used - precipitation or diffusion.

Areas of application

Material used in manufacturing:

• tavra, I-beam;
• corners, gussets;
• sheets, channels.

During production, manufacturers must comply with certain rules that are specified in government documents:

• GOST 8239;
• GOST 8509;
• GOST 8510;
• GOST 19425;
• GOST 19903;
• GOST 8240;
• GOST 7511;
• GOST 82.

The material is used in construction:

• TPP, nuclear power plant;
• educational buildings, scientific laboratories;
• frames for different buildings;
• technical trailers;
• overpasses, bridges;
• masts, towers.

Good weldability allows you to create structures of different shapes. Riveted joints are used for assembling metal structures that are subject to vibration loads.

Use of steel 17G1S

The durability of the finished steel allows it to be used in a wide variety of areas. However, the main direction is the production of industrial parts, which include bends, flanges, splitters and other elements of pipelines and highways.

Since the bulk of these objects are underground, strong pressure and temperature changes are exerted on their surface

Therefore, it is important to choose an item that can withstand these factors without problems for many decades. If necessary, you can choose any foreign analogue of the 17G1S model: Fe510D1 (Germany), SM490A (Japan), 350W (Canada), Fe52CFN (European Union), 16Mn (China) and many others

Alternative options are almost identical in characteristics, and have no restrictions for welded structures.

Pipeline outlet made of steel 17G1S

Treatment

The material lends itself well to mechanical processing. The quality of welding is affected by the carbon content. For this material, the percentage of this component does not exceed 0.25%. This explains the ease of weldability of the alloy. The seam is strong, without internal voids. No cracks form inside or on the surface. To obtain a high-quality connection, when carrying out welding work, there is no need to perform additional operations - forging the seam, preheating the surfaces to be joined.

The ability to use metal for cold rolling depends on the ductility index. Relative tensile elongation - up to 24%. The size of the yield area is up to 2.4%. These figures show that this alloy can be effectively processed by flexible forming. To work with thick sheet metal, you need to preheat the workpieces. This will make it easier to process, and cracks will not form on metal surfaces. Thin sheets may crack when bending. To prevent this from happening, you need to heat the material and increase the bending radius.

S235 steel does not contain expensive additives and has a low price. It can be used in different directions, but we must not forget about the reduced strength and hardness.

Weldability

The weldability of structural steel C235 is determined based on a special formula that calculates the equivalent amount of carbon in the composition:

where the letters indicate the percentage of carbon, manganese, chromium, nickel and copper, respectively. In this case, Se will be less than 0.25%, which indicates easy weldability. Cracks do not form in the weld area during welding and during cooling. Welding work is carried out without preheating, forging, etc.

Steel C235: characteristics, properties, composition

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It often happens that you need to study a large layer of information, but, as usual, there is little time. In such a situation, articles like this one are very helpful: informative and concise. For example, this short review contains all the most necessary information regarding the C235 steel grade: its composition, properties, analogs, interpretation and scope of application. Having studied it, anyone can easily find the type of metal they need, if necessary.

Decoding the steel grade

Let's start with what this steel is called. After all, its symbol can tell a lot of useful information. So a professional who knows how to “read” alloy grades will immediately understand that C235 is a construction, structural, low-alloy steel. This is evidenced by its marking, in which the letter “C” denotes its direct purpose - use in building structures, and the addition of numbers is the yield strength of the alloy, expressed in units of measurement - megapascals. This characteristic of steel is very important for industrial alloys, as it helps to calculate the maximum load that parts made of a particular metal can be subjected to without the risk of further critical deformation and, as a result, breakage.

Chemical composition of the alloy

The fact that C235 steel is low-alloy does not mean that it does not contain any chemical impurities and additives that would give the material any outstanding properties. Yes, of course, the list of additives in general is not so extensive when compared with more specific types of steel, but chemical additives are still present in the composition of C235 steel. GOST is proof of this. This document, certified by all authorities, provides a list of alloying elements:

• Carbon (0.2%). The steel belongs to the low-carbon class and has reduced hardness characteristics, which reduces the final strength, but significantly increases ductility and facilitates machining.
• Silicon (0.05%) is a natural deoxidizer, which at this dosage slightly increases the strength of steel, its heat resistance and ductility.
• Manganese (0.6%) - improves the structure of steel, giving it strength, however, it has little effect on its other indicators.
• Nickel, chromium and copper (0.3% each). The effect of impurities is generally identical and is aimed at increasing corrosion resistance, heat resistance and overall strength.
• Phosphorus, sulfur (up to 0.05%) are harmful impurities that negatively affect the structure of the alloy. However, their content as a whole is negligible.

Alloy characteristics

Now that the chemical composition of steel has been studied, the following theses can be put forward regarding the characteristics of C235 steel:

1. Plastic. The alloy does not have high hardness due to the low carbon content in the composition, as well as due to some additives that give the metal even greater ductility. Due to this, firstly, facilitation of mechanical processing is achieved: giving a sheet of C235 steel a shape by bending without preheating, straightening with a special tool, cold pressing, etc. Secondly, the risk of defects forming in the part when it is loaded is reduced.
2. Weldability. The construction of building structures is difficult to implement without the participation of a welding machine, and therefore the material from which they will be made must have good weldability. And steel grade C235 fits perfectly. After all, it can be welded without preheating in any way and without fear of cracks forming at the seam.
3. Corrosion resistance. Steel's resistance to oxidation and rust is very important. After all, this indicator determines how soon this or that structure will become unusable. C235 steel has average resistance to corrosion, which allows it to be worked in conditions of normal humidity without the formation of rust.

Analogs and substitute steels

The rolled metal market is truly extensive and therefore for the same operation you can easily find at least a couple of steels with similar composition and characteristics. However, you need to know what exactly to look for. For steel C235, the list of substitute alloys is as follows:

• St18kp;
• St3kp2;
• VSt3kp2.

Knowing the list of these steel grades, any buyer at least triples his chance of purchasing building materials for his needs. Although, with a high degree of probability, a good consultant will be able to point out analogues of a particular alloy free of charge.

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Technical characteristics: subtleties of using reference manuals

The properties of 09g2s steel are largely determined by the chemical composition of the alloy, its specific parameters, which today are quite accurately calculated by metallurgists.

Steel grade 09g2s has the following critical points:

• Ac1 = 732, when austenite transforms into pearlite during cooling processes;
• Ac3(Acm) = 870 (s – from French chauffage/heating) the end point of cementite dissolution;
• Ar3(Arcm) = 854 (refroidissement – ​​cooling) the beginning of the release of Fe3C;
• Ar1 = 680 hypoeutectoid steel, corresponds to ferrite precipitation

The symbols are classic, numbers 1 and 3 indicate the numbers of points on the graph. The symbols cm usually mark hypereutectoid steels.

If we talk about other features of St 09g2s, the following characteristics are noted: easy weldability of the material. For this purpose, RDS, ADS under flux and gas protection are used. Only products that have undergone chemical-thermal treatment cannot be welded.

The mechanical properties of steel 09g2s are tabular values ​​that were developed by a number of GOST standards and describe the material at room temperature, as well as for its other states.

Among the important mechanical properties of 09g2s steel are the following:

• Yield strength for permanent deformation, measured in MPa;
• Relative values ​​of elongation at break and contraction;
• Impact strength (use under load is one of the main applications);
• Brinell hardness (HB).

Strength class of steel 09g2s: the table for the list of grades includes the one indicated, which, as already noted, corresponds to C345. This also includes a number of other brands. Thus, steels that are different in chemical composition and even in the method of producing steel can have the same strength class. This data can be found for 09g2s according to GOST 19281-2014; the characteristics of the alloys are presented in convenient tables that are easy to navigate. You can view (download) GOST 19281-2014 here.

But the opposite situation is also possible. For example, for 09g2s GOST 19281-89 and grade 16GS there is data on strength classes 265 and 296.

The same GOST describes the types of rolled metal:

• Varietal, round, shaped with various sections (including circle 09g2s).
• Wideband profiles with a certain thickness of products.

Large diameter circles steel 09g2s

Similar information is provided for other brands.

The density of steel 09g2s fluctuates, somewhere around the 7800 kg/m3 mark. But alloying elements can either increase the specific gravity or reduce it. Tungsten tends to be the first. The second is achieved by adding: cobalt, nickel, copper.

The hardness of steel 09g2s can be determined by Brinell, Rockwell, Vickers, etc. the choice of system is determined by the type of products for which parameter determination is required. It is also important when choosing a welding method; the hardness of the steel at the weld should remain fairly high.

Most of the listed parameters can be found in TU 14 3 1128 2000 for steel 09g2s, as well as for other grades. The technical specifications describe the requirements for the materials from which pipes are made for servicing gas fields and other areas of the industry.

The permissible stress for steel 09g2s is calculated depending on the following values:

• strength class and grade;
• temperatures at which it will be operated;
• thickness, sometimes configurations (circle, sheet, etc.).

Existing 09g2s analogues are foreign (European, Asian, others), most similar in mechanical and technical properties to the specified brand. However, the chemical composition can vary greatly. The Bulgarian version of this brand has the closest configuration.

C235 - classification and application of the brand

Material classification: Steel for building structures

Application: production of rolled products intended for building steel structures with welded and other connections

C235 - chemical composition of the material as a percentage

C235 - mechanical properties at a temperature of 20°

Steel 09g2s 12: decoding

Understanding how labeling is formed allows you to clearly understand what product the manufacturer represents, as well as its main features. For those who are interested in details about 09g2s, the breakdown of steel is as follows:

• 09 – quantitative fraction of carbon content in the alloy (0.09%);
• G2 is manganese and its part in the entire volume fluctuates around 2% (the exact figure ranges from 1.3 to 2%);
• C – denotes silicon, the absence of numbers after the symbol indicates that it is less than 1%.

*after the steel grade (with a dash) the category is written (example: 09G2S-12). The category indicates for which standardized characteristics the rolled metal was tested.

Thus, the decoding of 09g2s clearly looks like this:

As can be seen from the table, the interpretation of steel 09g2s is not limited to only three alloying components. In addition to carbon, silicon and manganese, it is supplemented by the following elements: nickel, sulfur, phosphorus, chromium, nitrogen, copper, etc. The percentage component of alloying metals is no more than 1-2 total%.

Marking 09g2s on a steel sheet

Also, for steel 09g2s, not only the alloying level is taken into account, but also other factors. Here are just a few of them that are significant for a particular case:

• constructiveness (purpose);
• eutectoid (structure: hexagonal, cubic, etc.; changes after hardening, etc.);
• production method (open hearth, conventional or electric steel);
• chem. steel composition 09g2s (in this case low-alloy).

As a result, analogues appear in relation to which questions like the following are often asked: is 345 steel 09g2s? The designation C345 was introduced for builders, where the numbers do not indicate the chemical composition of the material, but its important property - the yield strength; for steel 09g2s it corresponds to the construction standards C345, which is reflected in a number of GOSTs (27772-88). Below we consider several classic options, including when one grade of steel corresponds to several strength classes

Below, several classic options are considered, including when one grade of steel corresponds to several strength classes.