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Introduction to the classification numbers and use of steel

一, the classification of steel

classification of steel

  1. According to chemical composition, it can be divided into:
    ⑴ Carbon steel (non-alloy steel) : low carbon steel, medium carbon steel, high carbon steel
    Alloy steel: low alloy steel, medium alloy steel, high alloy steel
  2. Classification of Steel By quality:
    ⑴ Ordinary quality steel: S: 0.035 ~ 0.055%; P: 0.035 ~ 0.045%
    ⑵ High quality steel: S, P≤ 0.035%
    ⑶ High quality steel: S≤0.020~ 0.030%; P 0.025 ~ 0.035% or less
    ⑷ Super grade high quality steel: S≤ 0.015%; P 0.025% or less
  3.  Classification of Steel By use:
    ⑴ Structural steel:
    1) Steel for engineering structure: used to manufacture various engineering components, such as Bridges, ships, building components, etc.
    2) Steel for machine parts: including carburized steel, tempered steel, spring steel, rolling bearing steel.
classification of steel

Tool steel: used to manufacture all kinds of tools, measuring tools, molds, etc., generally for high carbon steel, in quality are high quality steel or high quality steel.
⑶ Special performance steel: steel with special physical or chemical properties, used for parts or structures with special requirements, such as stainless steel, heat resistant steel, high wear resistant steel, magnetic steel, etc classification of steel

  1. Common carbon structural steel:Mainly to ensure the mechanical properties, the brand reflects the mechanical properties.
    With Q+ numbers, “Q” is the yield point, “qu” Pinyin, the number represents the yield point value. For example: Q-275, indicates that the yield point is 275MPa, if the label is marked with letters A, B, C, D, it indicates that the steel quality grade is different, that is, the CONTENT of S and P is different. The quality of A, B, C and D improved successively, “F” stands for boiling steel, “B” for semi-killed steel, and those not marked “F” and “B” for killed steel. For example, Q235-A•F refers to class A boiling steel with yield point of 235MPa, and Q235-C refers to Class C killed steel with yield point of 235MPa.
    Ordinary carbon structural steels are normally used directly in supply without heat treatment. Usually Q195 (A1), Q215 (A2), Q235 (A3) carbon content is low, there is a certain strength, often tied into thin plate, steel bar, welded steel pipe, used for Bridges, buildings and other steel structures, but also can manufacture ordinary rivets, screws, nuts, washers, anchor bolts, bushing, pin shaft and so on, Q255 (A4) and Q275 (A5) steels have high strength, good plasticity and toughness, and can be welded. It is usually made of shaped steel, strip steel and steel plate as structural parts and the manufacture of connecting rods, keys, pins, gears and shafts on simple machinery,classification of steel etc.classification of steel

2. High quality carbon structural steel:

  • At the same time to ensure the chemical composition and mechanical properties of steel. The brand number is a two-digit number representing the average carbon content of steel in a few ten-thousandths. For example, 45 steel indicates that the carbon content of steel is 0.45%; 08 steel means the carbon content of steel is 0.08%. If the manganese content in the steel is high, the manganese element must be marked, such as 0.45%C, Mn0.70 ~ 1.00% steel is 45Mn.
    High quality carbon structural steel is mainly used for manufacturing machinery parts. Usually go through in order to improve the mechanical properties, heat treatment according to carbon content is different, have different purposes, 08, 08 f, 10, 10 f steel, good plasticity and toughness, excellent cold formability and weldability, cold rolled sheet, often used to produce shells of instrument, automobile and tractor on cold stamping parts, such as the automobile body, the tractor cab, etc.; 15, 20, 25 steel for the production of small size, light load, surface wear resistance, core strength requirements are not high carburizing parts, such as piston steel, template, etc.; 30, 35, 40, 45, 50 steel after heat treatment (quenching + high temperature tempering) with good comprehensive mechanical properties, that is, with high strength and high plasticity, toughness, used for making shaft parts; 55, 60, 65 steels have high elastic limit after heat treatment (quenching + high temperature tempering) and are commonly used as springs.

3. Carbon tool steel:

  • The grade of this kind of steel is indicated by carbon or T followed by a number. The figure represents the average carbon content of steel in thousandths of a percentage point. T8 and T10 are carbon tool steels with an average carbon content of 0.80% and 1.0% respectively. For high quality carbon tool steels, “A” shall be appended at the end of the steel number. Such as T12A.
    Carbon tool steel is used for manufacturing various measuring tools, cutting tools, molds, etc.
    Carbon tool steel has high hardness after heat treatment (quenching + low temperature tempering), which is used to manufacture measuring tools, cutting tools and molds with small size requiring wear resistance.
    T7, T7A, T8, T8A, T8MnA are used to manufacture tools that require high toughness and bear impact load, such as small punches, chisels, hammers, etc.
    T9, T9A, T10, T10A, T11, T11A are used to manufacture the required toughness tools, such as drill, tap, turning tool, die, drawing die, saw blade……
    T12, T12A, T13, T13A steel has high hardness, high wear resistance, but low toughness, used for manufacturing non-impact tools such as gauges, plug gauges, templates, files, scrapers, fine turning tools, etc.

4. The casting of the carbon steel

  • The grade is composed of “ZG” + two groups of numbers: the first group represents the yield strength value and the second group represents the tensile strength value.
    In fact, this kind of steel belongs to the structural steel, mainly used for manufacturing complex shapes, mechanical properties of higher parts, the carbon content is generally 0.20%-0.60%, if the carbon content is too high, the plasticity becomes poor, and when casting cracks.