Steel St3: characteristics, decoding, GOST

Characteristics of steel grade St3ps

St3ps - Structural carbon steel of ordinary quality, welds well, welding is carried out without heating and without subsequent heat treatment, welding methods: manual arc welding, automatic submerged arc welding and gas protection, KTS, ESW.

According to GOST 27772-88, steel grade St3ps5 in its characteristics and properties is an analogue of steel for building structures S245, steel St3ps is an analogue of steel for building structures S275. For thicknesses greater than 36 millimeters, heating and subsequent heat treatment are recommended; it is not prone to flake sensitivity and there is no tendency to temper brittleness. Machinability by cutting in the hot-rolled state at НВ 124 and σв=410 MPa, Kυ hard alloy. = 1.8 and Kυ b.st. = 1.6, has found its application in load-bearing elements of welded and non-welded structures and parts operating at positive temperatures, and is actively used in general construction solutions. This grade of steel is used to produce parts and components of freight cars, power transmission line supports, excavators and forestry equipment, offshore structures, road bridges, building structures, oil and gas platforms. Forging is carried out at temperatures from 1300 to 750 0C, cooling is carried out in air.

Application of steel St3

When considering different grades of steel, you need to take into account the fact that they are classified according to the degree of deoxidation. This chemical process involves removing oxygen from the composition. Too high an oxygen concentration determines a decrease in physical and mechanical properties.

The classification is carried out as follows:

1. Calm is characterized by the fact that the composition includes from 0.16 to 0.3% silicon.
2. Semi-calm has an average concentration of the element in question.
3. Boiling differs in chemical composition from calm in that it contains at least 0.05% silicon.

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St3 material is marked accordingly. Various substances can be used to carry out a chemical process.

It is worth considering that a quiet one is much more expensive than other options. This can be associated with the following points:

1. The structure is homogeneous, thereby increasing the degree of protection of the material from environmental influences.
2. The composition includes a small amount of oxygen, which determines high performance.

When using mild steel, the following products can be manufactured:

1. Rolled sheets and shapes.
2. Fittings and parts that can be used to create a pipeline. Various pipes can be used to transport coolant or gas or other media. In order for them to withstand high loads and environmental influences, materials with strength and hardness must be used during production. In addition, attention is paid to cost, since alloys that are too expensive may be less practical to use. Steel 3 is more suitable for the manufacture of such products.
3. Primary and secondary elements used in the manufacture of suspended structures and railway elements. In the railway industry, the metals that are most in demand are those that have low cost and high performance. Due to the large size of suspended structures, the price of one square meter is also of great importance.

The semi-quiet variety of steel, which is also widely used, contains about one percent oxygen. Due to this, the characteristics of hardness and ductility are less pronounced. When using steel 3, the following can be produced:

1. Pipes. This type of material is widely used today. Pipes are used to create a heating system as load-bearing elements. It is worth considering that pipes can have different diameters and wall thicknesses. The alloy in question has relatively low corrosion resistance, so it is necessary to protect the surface from exposure to high humidity.
2. Sheet metal is also used extremely often, especially in the manufacture of cabinet products or cladding of load-bearing structures. The thickness can vary over a wide range. Rolled sheet metal can be used for cold bending or stamping. These two processes are characterized by high productivity. That is why the alloy in question is most widely used.
3. Squares and corners are often used to obtain load-bearing structures. They are characterized by high strength, since the edges significantly increase rigidity and can distribute the load. Corners and squares are characterized by a large number of parameters: sheet thickness, angle of planes, length and cross-sectional shape. The scope of application is the manufacture of load-bearing structures and strengthening of existing structures.
4. Various hexagons. They are also widely used and can be used in a wide variety of industries.

Steel sheet St3 hot rolled

Boiling alloys have become widespread due to their availability. They are the most affordable in terms of cost, and the resulting structure is characterized by a high degree of workability. In addition, the alloy lends itself well to heat treatment, but its performance is reduced due to the high oxygen concentration.

In conclusion, we note that many analogues of steel 3 have the appropriate performance characteristics. Foreign manufacturers use their own standards for labeling. At the same time, the concentration of harmful impurities is maintained within a certain range. The use of the most modern technologies makes it possible to reduce the amount of phosphorus and sulfur in the composition, making the material more durable and less fragile. In some cases, alloying elements are added.

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St3 steel can easily be called one of the most popular brands of steel alloys. This material can be found almost everywhere, from garden benches to complex welded structures. What causes this?

Interpretation of steel grade St3ps

Decoding steel: Letter St. indicate that the steel is of ordinary quality, although most steels are high quality. The numbers from 0 to 6 are the conventional brand number depending on the chemical composition and mechanical properties. Typically, the higher the number, the more carbon and the greater the strength. In our case, the number 3 indicates the carbon content in the alloy is 0.14–0.22%. The letters after the brand number indicate the degree of deoxidation: ps - semi-calm. Steels of the first group, such as St3sp, are supplied with guaranteed mechanical properties and are used mainly without heat treatment.

Production nuances

The characteristics of a metal are determined based on its chemical composition and manufacturing technology. The basis of ST3PS steel is ferrite - a solid solution of carbon, nickel and chromium. The more carbon a material contains, the higher its strength.

Undesirable impurities in the composition are sulfur (0.05%) and phosphorus (0.04%). Sulfur forms sulfur grains, which causes red brittleness in steel. Phosphorus interacts with ferrite, which reduces ductility when working at elevated temperatures and increases cold brittleness in the cold.

For the production of ST3PS steel, open-hearth and converter production methods are used. The basic characteristics of the metal are identical for any method, but the converter method has a lower cost.

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Supply St3ps

Supplied in the form of long products, including shaped steel according to the regulations of GOST 2590-88 Hot-rolled round steel , GOST 2591-88 Hot-rolled square steel , GOST 8239-89 Hot-rolled steel I-beams , GOST 19771-93 Equal-flange bent steel angles, GOST 19772 -93 Bent steel angles, unequal flanges , GOST 8278-83 Bent steel channels, equal flanges , GOST 8281-80 , unequal , GOST 8283-93 steel trough equal flange profiles , GOST 380-94 Carbon steel of ordinary quality , GOST 85 09-93 Steel corners hot-rolled equal flange , GOST 8510-86 rolled steel angles unequal-flanged , GOST 8240-97 Hot-rolled steel channels , GOST 535-88 Rolled bars and shaped carbon steel of ordinary quality , GOST 2879-88 Rolled hot-rolled hexagonal steel, GOST 19903-2015 Hot rolled sheet products , GOST 19904-90 Cold-rolled sheets , GOST 16523-97 Rolled thin sheets of high-quality and ordinary quality carbon steel for general purpose, GOST 503-81 Cold-rolled low-carbon steel strip, GOST 103-76 Hot-rolled steel strip , GOST 82-70 Hot-rolled steel Wide-band universal, GOST 3282-74 Wire Steel low-carbon general purposes , GOST 17305-71 Carbon structural steel wires, GOST 10705-80 steel power steel pipes , GOST 10706-76 Pipes steel eight-dimensional , GOST 3262-75 Pipes steel water and gap-pipes .

Carbon steel grade st3sp - ordinary quality

Substitutes

Steel StZps, Steel S245

Foreign analogues

Decoding steel St3sp

• The letters “B” indicate that this steel, supplied according to mechanical properties and with separate requirements for chemical composition,
• The letters "St" stand for "Steel"
• number 3 indicates the conventional brand number depending on the chemical composition,
• the letters "sp" - calm (degree of steel deoxidation),
• If the letter “sp” is followed by a number, then it indicates the category. If there is no number, then steel category 1. Depending on the category, steel has different standardized indicators (see below).

Type of delivery

• Long products, including shaped steel: GOST 2590-88, GOST 2591-88, GOST 535-88, GOST 2879-88, GOST 19771-93, GOST 19772-93, GOST 8278-83, GOST 8281-80, GOST 8282 -83, GOST 8283-93, GOST 380-94, GOST 8509-93, GOST 8510-86, GOST 8239-89.
• Thick sheet GOST 19903-74.
• Thin sheet GOST 19903-74.
• Tape GOST 503-81, GOST 6009-74.
• Strip GOST 103-76, GOST 82-70, GOST 535-88.
• Forgings and forged blanks GOST 8479-70.
• Pipes GOST 8734-75, GOST 10706-76, GOST 10705-80.

Characteristics, application and purpose

St3sp steel belongs to structural carbon steels of ordinary quality for general purpose and is used for the manufacture of the following parts and structures:

• Load-bearing elements of welded and non-welded structures and parts operating at positive temperatures.
• Shaped and sheet products (5th category) - for load-bearing elements of welded structures operating under variable loads: with a thickness of rolled products up to 25 mm in the temperature range from -40 to +425 °C;
• for rolled products with thickness over 25 mm in the range from -20 to +425 °C, subject to delivery with guaranteed weldability.

According to the international standard ISO 630:1995, St3sp steel is designated E 235-C (Fe 360-C)

Steel 3 is a widely used steel in the petroleum, petrochemical and oil and gas industries. Welded and stamped products can be made from steel of this grade:

• frames,
• frames
• heavy oilfield equipment skids
• bases (blocks)
• parts of drilling and production derricks and masts
• brake bands
• pulleys
• Cam couplings for drilling rigs
• keys
• stubs
• mud pump covers
• racks
• brackets
• gear housings
• drilling rig frames, etc.

Temperature of critical points, °C

Chemical composition, % (GOST 380-94)

Chemical composition, % (GOST 380-2005)

NOTE.

1. The mass fraction of chromium, nickel and copper in St3sp steel should be no more than 0.30% each.
2. The mass fraction of sulfur in St3sp steel should be no more than 0.050%, phosphorus - no more than 0.040%.
3. The mass fraction of nitrogen in steel should be no more than:
   smelted in electric furnaces - 0.012%;
4. open hearth and converter - 0.010%.
5. The mass fraction of arsenic should be no more than 0.080%.

Standardized indicators of St3sp steel by rolled category (GOST 535-2005)

NOTE

• The “+” sign means that the indicator is normalized, the “-” sign means that the indicator is not normalized.
• The chemical composition of steel according to heat analysis or in finished rolled products is in accordance with the order.

Parameters for the use of electric-welded straight-seam pipes made of St3sp steel (GOST 32569-2013)

NOTE. Groups of media, see table 5.1 GOST 32569-2013

Parameters for the use of electric-welded spiral-welded pipes made of St3sp steel (GOST 32569-2013)

NOTE. Groups of media, see table 5.1 GOST 32569-2013

Application of St3sp steel for fasteners (GOST 32569-2013)

Conditions for using St3sp steel for bodies, covers, flanges, membranes and valve assembly made from rolled products, forgings (stampings) (GOST 33260-2015)

Resistance of structural materials against crevice erosion (GOST 33260-2015)

NOTE. The coefficient of erosion resistance of a material is the ratio of the rate of erosive wear of the material to the rate of erosive wear of steel 12Х18Н10Т (taken as 1).

Mechanical properties of rolled products under tension, as well as cold bending test conditions (GOST 535-2005)

NOTE

1. By agreement between the manufacturer and the consumer, the following is allowed:
   reduction in yield strength by 10 N/mm2 (1 kgf/mm2) for shaped steel with a thickness of over 20 mm;
2. reduction in relative elongation by 1% (abs.) for shaped rolled products of all thicknesses.
3. It is allowed to exceed the upper limit of tensile strength by 49.0 N/mm2 (5 kgf/mm2), and by agreement with the consumer - without limiting the upper limit of tensile strength, provided that other standards are met. At the request of the consumer, exceeding the upper limit of temporary resistance is not allowed.

Impact strength of rolled products (GOST 535-2005)

NOTE

• The “-” sign means that the indicator is not standardized.
• Determination of the impact strength of round rolled products is carried out starting from a diameter of 12 mm, square - starting from the square side of 11 mm.
• It is allowed to reduce the value of impact strength on one sample by 30%, while the average value must not be lower than the standards specified in this table.
• Impact strength KCV is determined for rolled products with a thickness of up to 20 mm inclusive.

Mechanical properties of rolled products

Mechanical properties of forgings

Impact strength KCU (GOST 380-94)

Mechanical properties at elevated temperatures

Endurance limit

NOTE. Sheet 40 mm thick in hot-rolled condition.

Technological properties

Forging temperature, °C: beginning 1300, end 750. Cooling in air.

Cutting machinability - Kv tv.spl = 1.8 and Kv b.st = 1.6 in the hot-rolled state at HB 124 and σw = 400 MPa.

Flock sensitivity - not sensitive.

Tendency to temper brittleness - not prone.

Welding

Weldability - weldable without restrictions; welding methods: RDS, ADS with flux and gas protection, ESW and KTS. For thicknesses above 36 mm, heating and subsequent heat treatment are recommended.

It is allowed to use steel st3sp for welded connections of pipeline fittings at a temperature of the working medium (wall) from -20 to 300 °C.

Welding materials for electric arc welding

Welding materials for gas shielded welding

Welding materials for submerged arc welding

Welding materials for welding steel st3sp with other steels

Temperature of preliminary and accompanying heating and tempering when welding structures made of steel st3sp

Recommended welding modes for correcting weld defects

NOTE. * - along with the electrode brand UONI 13/..., it is possible to use the brand UONII 13/..., depending on the designation of the brand in the specifications of the electrode manufacturer.

Modes of electric arc welding of samples and products

NOTE. * - along with the electrode brand UONI 13/..., it is possible to use the brand UONII 13/..., depending on the designation of the brand in the specifications of the electrode manufacturer.

Modes of argon arc welding of samples for incoming inspection of welding materials

Linear expansion coefficient α*106, K-1

Young's modulus (normal elasticity) E, GPa

Thermal conductivity coefficient λ W/(m*K)

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Impact strength of steel St3ps

Mechanical properties of steel St3ps

Mechanical properties of steel St3sp according to GOST 380-94 regulations is sold in the form of hot-rolled steel with a cross-section of up to 20 mm, from 20 mm to 40 mm, over 40 mm to 100 mm, and also over 100 mm. Yield strength – 225, 235, 245 MPa. Tensile strength 370-480 MPa. Relative elongation after rupture is 23 – 26%.

Mechanical properties of St3ps steel according to the regulations of GOST 16523-89 and GOST 19903-2006 in the form of hot-rolled sheets. The cross-section is made from 1.5 mm inclusive to mm inclusive. The relative elongation after rupture is 23%, 25%, 26%. Below is the data in tabular form:

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.

Mechanical properties of St3ps steel at a temperature of 200C

Foreign analogues of steel grade St3ps

• Structural steel
• Tool steel