Steel St3sp: characteristics, chemical composition and properties

How does the abbreviation stand for?

Decoding of ST3PS steel is carried out in accordance with Gosstandart 380-2005:

• St – steel with a predominance of carbon;
• 3 – composition number;
• ps – semi-quiet (level of deoxidation).

Designations and interpretation of letters of alloying elements of steels

A – nitrogen (indicated in the middle of the mark) B – niobium C – tungsten D – manganese D – copper E – selenium K – cobalt M – molybdenum N – nickel P – phosphorus P – boron C – silicon T – titanium F – vanadium X – chromium C – zirconium Yu – aluminum Ch – rare earth

Alloy structural steels

At the beginning of the stamp there is a two-digit number indicating the carbon content in hundredths of a percent. Alloying elements are listed below. The number following the symbol of the element shows its content as a percentage; if there is no number, then the content of the element does not exceed 1.5%. Steel 30Х2М. This grade of steel contains about 0.30% carbon, 2% chromium, and less than 1% molybdenum.

Alloy tool steels

At the beginning of the brand there is a single-digit number indicating the carbon content in tenths of a percent. If the carbon content is more than 1%, the number is not indicated; then alloying elements are listed, indicating their content.

Chemical composition

Decoding the steel grade St3 indicates the main components in its composition - iron (97%) and carbon (0.14-0.22%). The main quality of the alloy—its hardness—depends on the carbon concentration. The steel also contains small amounts of:

• manganese – 0.4-0.65%;
• silicon – 0.15-0.17%;
• nickel and chromium – 0.3% each;
• arsenic – 0.08%;
• copper – up to 0.3%;
• sulfur – 0.05%;
• phosphorus – 0.04%;
• nitrogen – up to 0.008%.

A feature of the St3 alloy is the strict regulation of the content of harmful impurities - sulfur and phosphorus. Phosphorus reduces the plasticity of the metal when exposed to high temperatures, and sulfur, when interacting with iron, forms sulfides, causing the phenomenon of red brittleness. It should be noted that there is an increased concentration of nitrogen, which accounts for almost 0.1%. In accordance with GOST 380-2005, the alloy is marked with accompanying indices that indicate the degree of deoxidation, for example, St3Gsp:

• the first two letters indicate carbon steel of ordinary quality;
• the number “3” means the serial number of the brand according to this GOST;
• the sign “G” indicates a modification with a high manganese content;
• “sp”, “kp”, “ps” – degrees of deoxidation.

Substitutes for steel grade St3 can be:

• C245, according to GOST 27772-88;
• C285;
• VSt3Sp.

Foreign analogues are labeled according to different rules:

• A57036, K01804 – USA;
• 40B, 722M24, HFS4 – UK;
• 1.0038, DC03 – Germany;
• E24-2, E24-4 – France;
• SS330, SS400 – Japan;
• Fe360B, Fe360C – Italy;
• G235C – China;
• RSt360B – Austria;
• Fe235D – Hungary.

The product range includes:

• long and shaped steel according to GOST 2591-2006;
• sheets of various thicknesses and stampings;
• pipes and fittings, according to GOST 10705-80;
• tapes and strips that are produced in accordance with GOST 14918-80;
• wire of different sections.

Steel 3PS

Steel 3ps belongs to the category of structural and carbon-enriched steels with an ordinary level of quality. The above-mentioned 3ps steel fully complies with state and international standards, which is why it has the right to be used in the process of manufacturing products for export.
Accordingly, before shipment, the metal undergoes a series of thorough checks. The presence of additional impurities in the steel in the form of chemical elements makes it more durable and, accordingly, greatly expands the scope of its application. That is why 3ps steel contains carbon, copper, silicon, manganese, nitrogen, nickel, phosphorus, arsenic, sulfur and chromium.

Purpose of steel grade 3

It is thanks to the advantages of the material that metal processors and builders are eager to buy st3 for their work. Simplicity of welding, strength and ease of use make St3 steel an indispensable assistant in the production of many parts and hardware. It is made from:

• Welded and non-welded structures, the production of parts used at positive temperatures (shields, frames, casings, frames) is carried out.
• Rolled products up to 10 mm thick are used to produce frictionless, low-load parts, such as troughs or machine covers.
• Modified steel is used for the manufacture of channels, angles or I-beams, and shaped outer profiles.

The st3 circle can be used to create mounting fittings, meshes, clamps, water and gas pipes, wire and other elements.

Grade 3 steel is non-floczen sensitive, has no tendency to temper brittleness and has unlimited weldability. The affordable price of St3 also plays a role.

ST3ps structural carbon steel

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.

Characteristics of steel ST3

All characteristics of steel st3 are regulated by GOST 380-71 standards. Its composition can include from 0.14 to 0.22% carbon. Steel 3 has quality properties, which are determined by weldability, mechanical properties and corrosion resistance. The mechanical characteristics determine which group the steel belongs to: high-strength, regular or high-strength.

Chemical composition of steel ST3

Impact strength of rolled steel ST3

Mass fraction of steel elements St3sp according to GOST 380-2005

In open-hearth and converter smelting, the share of nitrogen is 0.01%. An increase in N < 0.013% is allowed, provided that the mass fraction of P is reduced by no less than 0.005% for each increase in the mass fraction of nitrogen by 0.001%. TU 14-1-5283-94: at the request of the consumer P < 0.035, S < 0.04.

Supply of VSt3ps

Supplied in the form of long products, including shaped steel according to the regulations of GOST 380-2005 Carbon steel of ordinary quality (grade), GOST 8281-80 Bent steel channels, unequal flanges, GOST 8278-83 Bent steel channels, equal flanges, GOST 8240-97 Hot-rolled steel channels . 2590-88 Hot-rolled round steel, GOST 8510-86 Hot-rolled unequal-flanged steel angles, GOST 19772-93 unequal-flanged bent steel angles, GOST 19771-93 Equal-flanged bent steel angles, GOST 11474-76 Bent steel profiles (technical conditions), GOST 850 9- 93 Hot-rolled equal-flange steel angles, GOST 9234-74 Bent steel sheet profiles with trapezoidal corrugation, GOST 103-2006 Long-rolled hot-rolled steel strip. Assortment, GOST 82-70 Hot-rolled broadband universal steel, GOST 82-70 Hot-rolled broadband universal steel, GOST 503-81 Cold-rolled low-carbon steel strip, GOST 8734-75 Seamless cold-deformed steel pipes, GOST 10706-76 Electric-welded straight-seam steel pipes ( technical requirements), GOST 10705-80 Electric-welded steel pipes, GOST 20295-85 Welded steel pipes for main pipelines (technical requirements)

Advantages and disadvantages

Among the strengths of this brand:

• Has excellent weldability under any heat treatment.
• Tolerances for the use of elements make it possible to obtain a large variation in mechanical properties.
• Low cost with wide application variations.
• Possibility of hardening with high frequency current (one of the most effective and economical technologies).
• Not prone to temper brittleness.
• Not flake sensitive.

The disadvantage that the St3 steel grade has, which is inherent in the entire class of carbon analogues, is the tendency to corrosion. Even surface treatment gives temporary results. Among other disadvantages:

• As a rule, the steel structure has a coarse or medium-grain structure. Also, when carburizing and nitriding is carried out, the grain is prone to rapid growth and increased fragility.
• Cannot be used for open use in northern climates.

Assortment

Steel grade St3 contains carbon in an amount of 0.14-0.22. Such rolled metal is produced in 2 ways: hot (heating up to 1100 ° C) or cold. The advantage of hot rolling is the absence of stress in the structure due to tempering from rolling heating. During cooling, cold hardening resulting from plastic deformation is naturally removed. Cold rolling is used to produce products with a thickness or diameter of less than 4 mm (due to the formation of scale during heating).

Hot-rolled sheet steel grade St3 (GOST 19903-2005) is intended for the manufacture of welded pipes and casing products. Good machinability by cutting and joining with all types of welding allows the production of products of any shape and size.

Steel grade C255 is an analogue of St3. Heavy-duty products are made from it by hot-rolling: beams, versatile angles, I-beams, rails.

Smooth-bore or periodic profile fittings, 2-4 strength classes, are rolled from ST3sp with a maximum percentage of chemical. elements for this brand: carbon content of 18-22%, manganese - 50-58%, silicon - 18-20%.

If hot-rolled steel sheet grade St3 undergoes additional drawing, its strength increases greatly.

Chemical and physical properties

Without steel grade St 3, in our time it is impossible to build, construct above-ground and underground communications, produce vehicles, units and machine tools.
Impurities in steel of this grade are no more than:

• chromium - 0.30 percent;
• nickel - 0.30 percent;
• copper - 0.30 percent;
• sulfur - 0.005 percent;
• phosphorus - 0.04 percent;
• nitrogen - 0.10 percent.

Steel deoxidation

The steel deoxidation process is a chemical process that removes oxygen from the molten raw material. In this case, it is determined by an impurity that worsens the mechanical and physical properties of the alloy.

According to the deoxidation process, St3 steel is divided into the following types:

1. Calm - deoxidation occurs with the use of manganese, silicon and aluminum.
2. Boiling - deoxidation using only manganese.
3. Semi-calm - deoxidation using aluminum and manganese.

The level of deoxidation is indicated in the marking of steel with the letters “kp”, “sp” and “ps”; their modification with an increased percentage of manganese is also indicated. For example – St3Gsp or St3Gps.

Boiling steel differs in chemical composition from calm steel in that the silicon content in it is very low, less than 0.05 percent. Calm steel contains more silicon, ranging from 0.16 to 0.30 percent. Since boiling steel contains more oxygen than calm steel, its quality is much worse than calm steel.

Semi-quiet steel occupies a middle position in quality between calm and boiling steels.

For the deoxidation process, elements such as silicon, manganese, and aluminum are used. The strength of their impact on steel varies. So, the “strongest” is aluminum, and the “weak” is manganese.

Quiet Steel is the most expensive steel in terms of cost. It lacks oxygen and is characterized by a homogeneous (homogeneous) structure, which, due to its nature, is designed to give the alloy maximum protection from environmental influences in the form of corrosion and ductility. Calm steel alloy St3 in accordance with GOST 380-2005 adopted in 2005, is used during the construction of rigid trusses and other metal structures, non-load-bearing and load-bearing elements. This grade of steel is used to make:

• sheet and packaged rolled products (steel sheet St 3);
• blanks for fittings and parts for pipelines (square pipe St 3);
• main and secondary elements for railway facilities, overhead and ground tracks, etc.

Semi-quiet steels occupy a neutral position between boiling and calm types of raw materials. In this form, a percentage of oxygen is already present, which gives the alloy less pronounced characteristics of ductility and hardness.

The chemical composition of this type of steel cannot be considered homogeneous. This grade of steel is used to produce rolled pipes and sheets, such a popular product as the St 3 beam. Semi-quiet steels are also used for the production of circles and strips, angles and squares, embedded parts and hexagons.

If we talk about boiling steels, then these are the most popular and affordable structural steel alloys. The production cost is low, but at the same time, blanks made from this steel (slabs, ingots, finished rolled sheets) lend themselves well to various processing under different thermal conditions.

The density of grade 3 steel of this modification is completely heterogeneous, however, subject to proper use and appropriate requirements, it is one of the most popular and inexpensive, practical types of alloys.

According to GOST 380-2005, it is stated that the manufacturer has the right to independently indicate the degree of deoxidation of raw materials if the customer has not determined it.

Mechanical performance

Mechanical indicators of the properties of St3 steel, which are used to control the properties of rolled raw materials:

• resistance that occurs temporarily - all categories;
• fluidity and its limit - all except the first category;
• bending under external influence in a cold state - all except the first category;
• relative lengthening - all existing categories are here;
• KCU (impact strength) at ambient temperature +20 °C – third category;
• KCU (impact strength) at an ambient temperature of –20 °C – fourth category;
• KCU (impact strength) after mechanical aging – fifth category;
• KC V (impact strength) at ambient temperature +20 °C – sixth category;
• KC V (impact strength) at an ambient temperature of –20 °C – seventh category.

Mechanical properties according to GOST 380-2005 standard

Mechanical properties according to GOST 535-2005 standard

By agreement with the consumer, for shaped steel with a thickness of more than 20 mm, the yield strength may be reduced by 10 MPa. The relative elongation may be reduced by 1% (by agreement with the consumer). The upper limit of tensile strength may be exceeded by 49 MPa, and by agreement with the consumer - without limiting the upper limit. limit of temporary resistance, provided that other standards are met. At the request of the consumer, exceeding the upper limit of temporary resistance is not allowed. * a - sample thickness, d - mandrel diameter Impact strength standards KCU, J/cm2

** Steel categories: 3 - steel with testing of mechanical properties for tensile strength on samples made from normalized blanks of the size specified in the order, but not more than 100 mm 4 - steel with testing of mechanical properties for tensile strength and impact strength on samples made from heat-treated (hardening + tempering) of workpieces of the size specified in the order, but not more than 100 mm 5 - steel with tensile testing of mechanical properties on samples made of steel in a cold-worked or heat-treated state (annealed or highly tempered)

Mechanical properties according to GOST 8696-74 standard

Impact strength standards KCV, J/cm2 (kgf⋅m/cm2)

Mechanical properties according to GOST 10706-76 standard

For main heating networks

* Steel categories depending on the standardized characteristics: 3 - steel with tensile mechanical properties tested on samples made from normalized workpieces of the size specified in the order, but not more than 100 mm 4 - steel with tensile and impact strength mechanical properties tested on samples, made from heat-treated (hardening + tempering) workpieces of the size specified in the order, but not more than 100 mm 5 - steel with tensile testing of mechanical properties on samples made from steels in a cold-worked or heat-treated state (annealed or highly tempered)

Mechanical properties according to GOST 10705-80 standard

Mechanical properties according to GOST 5781-82 standard

* c - thickness of the mandrel, d - diameter of the rod ** For reinforcing steel with a diameter of 20 to 40 mm, cold bending test at 180 °C: c=2d

Weldability of steel grade St3

Consumers enjoy working with this grade of steel. Its technical characteristics, taking into account modifications, are very universal. One of the most important advantages of this brand is its excellent weldability.

Steel allows the use of automatic arc and manual welding methods, as well as contact-spot and electroslag methods. St. 3 is also used for the manufacture of forged parts (fences, various gratings, etc.).

Technological properties St3sp

This steel is considered universal in its qualities.

It is not subject to brittleness after tempering, does not form flakes, and is characterized by excellent weldability using any technology.

St3sp5 decoding what 5 means

Steel.
Types and grades of steel. Their application. Steel is an alloy of iron and carbon with other elements, the carbon content in it is no more than 2.14%.

The most general characteristic is that steel is classified according to its chemical composition:

carbon steel (Fe – iron, C – carbon, Mn – manganese, Si – silicon, S – sulfur, P – phosphorus). Based on carbon content, it is divided into low-carbon, medium-carbon and high-carbon. Carbon steel is designed for statically loaded tools.

alloy steel - alloying elements are added: nitrogen, boron, aluminum, carbon, phosphorus, cobalt, silicon, vanadium, copper, molybdenum, manganese, titanium, zirconium, chromium, tungsten, nickel, niobium.

According to the production method and impurity content, steel differs:

ordinary quality steel (carbon less than 0.6%) – corresponds to GOST 14637, GOST 380-94. St0, St1, St2, St3, St4, St5, St6. The letters “St” indicate ordinary quality steel, the numbers indicate the marking number depending on the mechanical properties. It is the cheapest steel, but inferior in other qualities.

high-quality steel (carbon or alloy) - GOST 1577, carbon content is indicated in hundredths of % - 08, 10, 25, 40, the degree of deoxidation and the nature of solidification can additionally be indicated. High-quality carbon steel has high ductility and increased weldability.

Low-carbon high-quality structural steels are characterized by low strength and high ductility. Parts for cold stamping are made from sheet steel 08, 10, 08kp. Bolts, screws, nuts, axles, hooks, studs and other parts for non-essential purposes are made from steels 15 and 20.

Medium-carbon quality steels (st. 30, 35, 40, 45, 50, 55) are used after normalization and surface hardening for the manufacture of parts that have high strength and core toughness (axles, screws, bushings, etc.)

Steel 60 - steel 85 have high strength, wear resistance, and elastic properties. Crane wheels, rolling rolls, compressor valves, springs, leaf springs, etc. are made from them.

high quality - complex chemical composition with low phosphorus and sulfur content - according to GOST 19281.

Steel is also divided by application:

a) construction steel - carbon steel of ordinary quality. Has excellent weldability. The number indicates the conditional number of the steel composition according to GOST. The higher the reference number, the higher the carbon content, the higher the strength of the steel and the lower the ductility.

St0-3 - for secondary structural elements and non-critical parts (flooring, railings, lining, washers)

St3 is used for load-bearing and non-load-bearing elements of welded and non-welded structures and parts that operate at positive temperatures. GOST 380-88.

The quality standard provides for steel with an increased amount of manganese (St3Gsp/ps, St5Gsp/ps).

b) structural steel - GOST 1050

Carbon-based high-quality structural steels are used in mechanical engineering, for welded, bolted structures, for roofing work, for the manufacture of rails, railway wheels, shafts, gears and other parts of forklifts. The numbers in the marking indicate the carbon content in tenths of a percent.

St20 - lightly loaded parts, such as rollers, copiers, stops,

St35 - experiencing small stresses (axles, rods, levers, disks, traverses, shafts),

St45 (st40Х) - requiring increased strength (shafts, couplings, axles, racks)

Structural alloy steels are used for tractor tracks, the manufacture of springs, leaf springs, axles, shafts, automobile parts, turbine parts, etc.

c) tool steel - used for cutting tools, high-speed steel for cold and hot deformation of materials, for measuring instruments, for the production of hammers, chisels, chisels, cutters, drills, files, razors, rasps.

U7, U8A (the figure is tenths of a percent in terms of carbon content). Carbon steels are produced in high quality and high quality. The letter "A" stands for high quality carbon tool steel.

d) alloy steel - universal steel containing a special impurity. Silicon content more than 0.5%, manganese more than 1%. GOST 19281-89. If the content of the alloying element exceeds 1 - 1.5%, then it is indicated by a number after the corresponding letter.

low-alloy steel - where alloying elements are up to 2.5% (09G2S, 10HSND, 18KhGT). Low-alloy steel can be used in conditions of the far north, from -70 degrees C. Low-alloy steel is distinguished by greater strength due to a higher yield strength, which is important for critical structures.

highly alloyed (from 10 to 50%)

Steel 09G2S is used for steam boilers, apparatus and containers operating under pressure and temperatures from minus 70 to plus 450 degrees; it is used for critical sheet welded structures in chemical and petroleum engineering, and shipbuilding.

Steel 10HSND is used for welded structures in chemical engineering, shaped profiles in construction, and carriage building.

18ХГТ is used for parts operating at high speeds under high pressure and shock loads.

e) special purpose steel - steel with special physical properties. It is used in the electrical industry and precision shipbuilding.

The weldability of steel is affected by the degree of its deoxidation. According to the degree of deoxidation, steel is classified:

mild steel (st3sp) - completely deoxidized with a minimum content of slag and non-metallic impurities,

Mechanical restoration

Parts made from steel grade ST3PS are processed using pre-selected equipment and speed. This ensures that the required performance indicators are maintained, reduces local stresses, etc.

Sharpening and milling is carried out using a cutting tool made of VK8 or T5K10. Internal and external threads are created using taps and dies made of R18 and R6M5 steel. When processing on a machine, it is necessary to use cutting fluids, and when processing manually, castor oil.

The impact strength of ST3PS steel allows products to be processed on machine tools under constant vibration load. The speed depends on the properties of the alloy; other parameters are also selected:

• thickness 6-10 cm – tool holder 16*25 mm;
• cutting depth 3 mm – feed speed 0.7-1.2 mm/rev;
• rotation speed 700 rpm.

Where and how is it used?

The performance qualities allow the alloy to be used for the manufacture of elements of welded structures operating under load, machine parts and mechanisms. The operating temperature must be above 0 degrees. The fifth category of rolled elements can be used in conditions of negative temperatures -40/-425 C under the action of a variable load.

Complex products require subsequent heat treatment; annealing is most often used. It reduces residual stresses after welding. The scope of application of ST3PS includes the production of At-400S fittings.

The sheets are used to produce parts using cold stamping. The result is pallets for collecting cutting fluids in production, containers of various volumes and purposes, casings, etc.

Technological properties

Metal is welded by any known method, including electric and manual welding. Its main characteristics include:

• weldability;
• high mechanical qualities;
• anti-corrosion properties.

Thanks to this data, the class of steel is determined - regular, high-strength and high-strength. After welding, heat treatment is carried out only when the thickness is more than 36 mm. This reduces residual stresses, ensuring long service life and resistance to wear.

Production Features

The properties of the finished material are determined by the substances that make up its composition and largely depend on what technologies were used in the production of a particular alloy.

The basis of the steel alloy is ferrite. It is a component of iron-carbon alloys. It is, in fact, a solid solution of carbon and alloying components. To increase its strength, the melt is saturated with carbon.

Impurities from which nothing but harm can be expected include phosphorus and sulfur, as well as their derivatives. Phosphorus, reacting with ferrite, reduces the ductility of the alloy when exposed to high temperatures and increases brittleness when exposed to cold. During the melting process, iron sulfide may be formed, which can lead to red brittleness. St3 steel contains no more than 0.05% sulfur and 0.04% phosphorus.

For the production of structural steels, two steelmaking technologies are used:

• open hearth;
• converter

The parameters of the St3 grade, obtained by one or another method, differ little from each other, but the converter technology is simpler and cheaper.

Application of St3sp steel, taking into account characteristics and properties

This type of steel is one of the most popular in construction and industry.

The absence of oxygen in the alloy and a homogeneous structure are factors that increase resistance to corrosion in aggressive environments. These qualities, as well as high ductility, make this steel indispensable in the production of structures and elements that have high rigidity requirements.

These are rolled products - sheet and shaped (channels, I-beams and T-beams, angles), blanks for fittings, pipeline elements (in particular, square pipes), etc.

The characteristics of steel make it possible to construct supporting load-bearing structures and frames from it, the operation of which is carried out in difficult conditions.

Elements and parts are made from St3sp steel without heat treatment, which makes it possible to preserve all the characteristics of the alloy - flanges, tees, transitions.

Steel is also used as a base layer in the production of hot-rolled 2-layer sheets that are resistant to corrosion.

Application of material

The main characteristics of one of the most popular materials, such as maintaining the strength of the material despite high loads and a wide range of withstandable temperatures, allow the use of 3ps steel in load-bearing structures. Another advantage is the absence of the need to heat the metal before welding and heat treatment after welding.

Thanks to this, St3ps is used in production:

• Rolled sheet metal with a thickness of material within 10 mm, used for the construction of load-bearing structures connected by welding and used under varying influence of weight on elements from 11 to 25 mm in thickness.
• In the manufacture of reinforcement with a smooth profile used in the reinforced concrete industry.
• Production of profile parts for agricultural engineering.
• Production of expanded metal sheets.
• Manufacturing of pipeline parts.
• Production of connecting profiles for pipeline structures designed to operate under temperature conditions from -20 to +200°.
• Production of electric welding pipes.
• Production of the main layer of cladding for products requiring resistance to wear and corrosion.

Analogs

As already noted, the St3 grade is in demand in the production of various structures, and in fact, is the most popular structural steel. This is the reason why it is produced by metallurgical plants located in all parts of the world, for example:

• USA - A284Gr.D, A57036;
• Germany - 1.0038;
• Japan - SS330;
• European Union - Fe37-3FN;
• China - Q235.

Suppliers of steel produced outside our country must submit documents confirming the compliance of imported materials with domestic GOST and TU.

Similar foreign steels

The metal is one of the most common structural steels. Therefore, analogues of ST3PS include foreign products:

• Q235;
• S235J0;
• Fe235D;
• 1.0038;
• K01804 and D.

When purchasing foreign product ranges, you must ensure that they comply with GOST and TU requirements.

Sources

• https://nzmetallspb.ru/stanki/stal-st3-marki-harakteristiki-himicheskij-sostav.html
• https://molotok34.ru/spravochnik/st3ps-rasshifrovka-stali.html
• https://svarkaipayka.ru/material/stal/tehnicheskie-harakteristiki-uglerodistoy-stali-3.html
• https://promkrepez.ru/info/steel-grades/stal-marki-st3/
• https://metal.place/ru/wiki/st3sp/
• https://punktpriema.ru/articles/tehnicheskie-harakteristiki-konstruktsionnoy-stali-st3.html
• https://stanok.guru/stal/fiziko-himicheskie-harakteristiki-staley-st3.html