What does 20MnSi mean in steel?

Composition & Properties:

Grade: 20MNSI, UNS, standard: YB(T)27(1)-89

Chemical composition (%) residual chromium, nickel, copper, c+1 6mn<=

Form of threaded steel bar form Hot rolled.

Tensile strength MPA 510 Yield strength MPA 345 Elongation % 18

Rules for Attached Grades:

The alloy element symbol and Arabic numerals specified in the standard are indicated, but the average carbon content number is generally not indicated, for example: the average carbon content is , containing chromium, molybdenum, and vanadium respectively22% alloy tool steel, whose grade is expressed as "CR12MOV"; The average carbon content is tungsten, molybdenum, chromium and vanadium

00% high-speed tool steel, whose grade is expressed as "W6Mo5Cr4V2".

If the average carbon content is less, an Arabic numeral can be used to indicate the carbon content (in parts per thousand). For example, an alloy tool steel with an average carbon content, manganese content, and silicon content is expressed as "8mnsi".

Low chromium (average chromium content Alloy tool steels, add the number "0" before the chromium content (in parts per thousand). For example, an alloy tool steel with an average chromium content is denoted as "CR06".

The manganese content in 20mnsi steel is between, the silicon content is between, and the carbon content is between.

However, when the manganese content exceeds %, due to the enhanced hardenability, the microstructure of the hot-rolled steel is likely to transform into bainite or martensite, and the toughness is significantly reduced. If the MN content is low, it is relatively high Mn, and the cooling is abundant under the same cooling conditions, and it can obtain a good structure, and has good bending and twisting resistance. Hot-rolled ribbed steel bars are divided into three grades: HRB335 (old grade 20mnsi), HRB400 (grade 20mnsiv, 20mnsinb, 20mnti) and HRB500.

Reinforced concrete steel bar refers to the reinforced concrete with straight bar or wire strip steel, its shape is divided into two kinds of light round steel bar and deformed steel bar, and the delivery state is straight bar and disc round two. The light round steel bar is actually the small round steel and disc round steel of ordinary low carbon steel. Deformed reinforcement is a rebar with a ribbed surface, usually with 2 longitudinal ribs and transverse ribs evenly distributed along the length direction.

There are three types of transverse ribs: spiral, herringbone, and crescent. It is expressed in millimeters of nominal diameter. The nominal diameter of the deformed reinforcement is equivalent to the nominal diameter of the light round reinforcement with equal cross-section.

Steel bars are mainly subjected to tensile stresses in concrete. Deformed steel bar due to the effect of ribs, and concrete has a larger bonding capacity, thus can better withstand the effect of external force. Steel bars are widely used in various building structures, especially large, heavy, lightweight, thin-walled and high-rise building structures.

20mnsi is a steel grade with high strength and good comprehensive properties, which is a building material. 20mnsi is the old national standard, and now it is the second part of steel for reinforced concrete for construction, and hot-rolled ribbed steel bar. The old name of the secondary hot-rolled ribbed steel bar (HRB330) has been phased out.

20mnsi chemical composition.

1. Carbon (c).

2. Manganese (MN).

3. Nickel (Ni).

4. Silicon (Si).

5. Phosphorus (P).

6. Sulfur (S).

7. Chromium (CR).

8. Copper (Cu).

9、c+1/6mn≤

<> high-manganese low-carbon permeable steel. 20Mn steel contains more abundant manganese elements, due to the high content of manganese metal, so compared with 15Mn steel, it has more high-quality characteristics, both in strength and plasticity, as well as in machinability and permeability, it is very superior. Another good feature is that in the process of quenching or carburizing, there will not be too many soft spots on the surface of the steel, which creates very good innate conditions for carburizing, and not only that, but it is also very convenient for carbon and nitrogen to be incorporated together.

30mn steel has higher strength and hardenability than No. 30 steel, medium weldability, cold deformation, medium plasticity, good machinability, and is generally used in the normalized state to manufacture bolts, nuts, levers and small parts working under high stress.

Features and scope of application:Low-carbon carburizing steel with high manganese content (W mn) is strong due to high manganese. Plasticity.

The machinability and hardenability are slightly higher than that of 15 steel, and there are fewer soft spots formed on the surface during carburizing and quenching, so carburizing is appropriate. Carbonitriding treatment obtains the comprehensive properties of surface wear resistance and good core toughness. Good toughness after hot-rolled or normalizing treatment.

Suitable for gears. Crank shaft, bracket. Chain.

Screw. Nut. Riveting and welding structural parts, plates are suitable for the manufacture of oil tanks, etc.

Farm tools in cold regions, such as cream jars, etc.

Chemical Composition:Carbon C:

Silicon Si: Manganese Mn: Sulfur S:

Phosphorus p:

Chromium cr:

Nickel ni:

Copper cu:

Mechanical Properties:Tensile Strength b (MPa): 540(55)Yield Strength s (MPa): 315(32)Elongation δ5 (%20

Section shrinkage 45

Impact power AKV (J): 63

Impact toughness value kv (j cm2): 78(8)Hardness: 217HB without heat treatment; Annealed steel 187HB specimen size: specimen size is 25mm

Heat treatment specifications and metallographic structure:Heat Treatment Specification: Normalizing, 880; quenching, 860; Tempering, 600.

Delivery Condition: Delivered in non-heat-treated or heat-treated (annealed, normalized or high-temperature tempered) condition. If the delivery is required in the state of heat treatment, it shall be indicated in the contract, and those who are not specified shall be delivered according to no heat treatment.

30MN steel is a kind of low-carbon carburizing steel with high manganese content, higher strength and hardenability than No. 30 steel, medium weldability, cold deformation, medium plasticity, good machinability, generally used in the normalized state, used to manufacture bolts, nuts, levers and small parts working under high stress.

Chemical Composition: Carbon C:

Silicon Si: Manganese Mn: Sulfur S:

Phosphorus p:

Chromium cr:

Nickel ni:

Copper cu:

Mechanical Properties:Tensile Strength b (MPa): 540(55)Yield Strength s (MPa): 315(32)Elongation δ5 (%20

Section shrinkage 45

Impact power AKV (J): 63

Impact toughness value kv (j cm2): 78(8)Hardness: 217HB without heat treatment; Annealed steel 187HB specimen size: specimen size is 25mm

30Mn2 belongs to the national standard alloy structural steel, and the implementation standard: GB T 3077-2015

30mn2 has medium plasticity when cold deformed, and the machinability and weldability are acceptable, but the parts need to be preheated to more than 200 before welding. The wire drawing, cold heading and heat treatment process has good performance, high hardenability, critical quenching diameter in oil, and small quenching deformation, but there are overheating, decarburization sensitivity and tempering brittleness. The steel has high strength, toughness and wear resistance after quenching and tempering, and the static strength and fatigue strength are also good.

This kind of steel is mostly used in the quenched and tempered state, and is mostly used as stamping parts (4 11 mm steel plates) to manufacture girders, beams, gearbox gears, shafts, cold heading bolts, and quenched and tempered parts with larger cross-sections in automobiles, tractors and general machinery manufacturing. In addition, this steel can also be used as carburizing steel to make carburized parts with high core strength requirements, such as mining crane rear axles and journals.

The chemical composition of 30mn2 is shown in the figure below

30mn2 is a relatively ordinary bearing steel, structural steel, its material has been reflected in their brand name, it is not difficult to see that it is a low-end medium carbon quenched and tempered manganese steel.

The strength, plasticity and wear resistance of 30mn2 steel are high, and the machinability and heat treatment process performance are relatively good, but it is easy to crack during heat treatment, with white spot sensitivity, low cold deformation plasticity, poor weldability, and needs to be preheated before welding.

30mn2 is commonly used in the manufacture of tractor frames, gears, bearings, cold heading bolts and quenched and tempered parts with large cross-sections. It can also be used to make carburized parts with high core strength requirements, such as crane axles and journals.

At present, there are many high-grade materials that can replace 30mn2, and the quality and service life of the workpiece can be improved according to the design requirements.

30Mn2 alloy steel is a material, and the type is alloy structure. Used in the manufacture of automobiles. Frame beams on tractors, gearbox gears. Axis. Cold heading bolts and quenched and tempered parts with larger cross-sections.

Used in the manufacture of automobiles. Frame beams on tractors, gearbox gears. Axis. Cold heading bolts and quenched and tempered parts with larger cross-sections. It can also be used to make carburized parts with high core strength requirements, such as crane axles and journals.

Chemical Composition: Carbon C:

Silicon si:manganese mn:

Mechanical properties: Tensile strength b (mpa): 785

Elongation δ5 (%)12

Section shrinkage 45

Work of impact absorption (impact value) (aku2 j): 63

Steel annealed or tempered at high temperatures**Brinell hardness HBS 10 3000 : Unheat treated just 207

Heat treatment Quenching Temperature 1st quenching 840 2nd quenching --Coolant Water.

Temper at a temperature of 500 coolant water. Empty.

Specimen size: specimen blank size mm: 25

30mn2 alloy structural steel.

Standard: GB T 3077-1988

Features and scope of application:

After quenching and tempering, it has high strength, toughness and wear resistance, and good static strength and fatigue strength. It is used as an important fastener for small cross-section, which can be used as frame longitudinal beam, gearbox gear, shaft, cold heading bolt and quenching and tempering parts of larger cross-section; In mining machinery, carburized parts with high central strength requirements, such as crane rear axles and journals.

Chemical Composition: Carbon C:

Silicon si:manganese mn:

Sulfur S: Permissible residual content

Phosphorus p: permissible residual content

Chromium Cr: Permissible residual content

Nickel Ni: Permissible residual content

Copper Cu: Permissible residual content

Mechanical Properties: Tensile Strength B (MPa): 785(80)Yield Strength S (MPa): 635(65)Elongation δ5 (12.)

Section shrinkage 45

Impact power AKV (J): 63

Impact toughness value kv (j cm2): 78(8)hardness: 207hb

Specimen size: The specimen blank size is 25mm

Heat treatment specifications and metallographic structure:

Heat treatment specification: quenched 840, water cooled; Tempered 500, water-cooled.

Delivery Status: Delivered in heat-treated (normalized, annealed or high-temperature tempered) or without heat-treated, the delivery status should be indicated in the contract.

Low-alloy steel refers to the addition of a small amount of alloying elements to the steel due to the strengthening of alloying elements, the yield point of low-alloy structural steel is 25-150% higher than that of ordinary carbon steel, plus most of them are low-carbon, and have good plastic toughness and welding performance, and some also have corrosion resistance, low temperature resistance and other characteristics, therefore, low-alloy steel is a very promising steel, and the proportion in the production of steel is increasing.

Low-alloy steels are divided into ordinary quality low-alloy steels, high-quality low-alloy steels, and special quality low-alloy steels according to their quality and use.

Low-alloy steels for general purpose.

Low-alloy structural steel for general purposes includes: ordinary quality and high-quality low-alloy structural steel, ordinary quality low-alloy steel refers to the production process that does not stipulate special quality control requirements for general use, high-quality, and requires special quality control in the production process (such as reducing sulfur and phosphorus content, controlling grain size, improving surface quality, etc.) The grade of general-purpose low-alloy steel structural steel consists of the Chinese pinyin letter (q) representing the yield point, the yield point value, and the quality grade symbol (A, B, C, D, e) The three parts are arranged sequentially, according to the grade of GB T1591-94 low-alloy high-strength structural steel.

In the old standard, the grade of low-alloy structural steel is represented by two-digit Arabic numerals and alloying element symbols and numbers, the number indicates the average carbon content (in a few parts per 10,000), when the average alloy content is less than that, only the element symbol is indicated in the steel number, and the content is not indicated; When the average alloy content is, write the finished product ...... accordinglyIts grade, chemical composition and performance are shown in the table.

Due to the action of alloying elements, general-purpose low-alloy structural steel has high strength and toughness, good process performance, low production cost, wide application, most of them are directly used, often used in railways, bridges, ships, automobiles, pressure vessels, and often used as welded structural parts and mechanical components.

Other low-alloy steels.

Other low-alloy steels, including ordinary quality, high-quality, and special quality low-alloy steels, are also special steels that need to be produced for a special product. High-quality steels that can be welded with low-alloy high-strength structural steels include low-alloy steels for boilers and pressure vessels, shipbuilding, automobiles, bridges, and bicycles; There are also special quality alloy steels for nuclear energy, pressure vessels, ships, weapons, and low alloy steels with guaranteed thickness direction. 20mnsi, 20mnti, 20mnsiv, 25mnsi, 20mnnbb used as general low-alloy steel reinforcement steel.

There are also low-alloy steels for railways and mines.