Carbon steel is an iron-carbon alloy with a carbon content of 0.0218% to 2.11%. It is also called carbon steel. It generally contains a small amount of silicon, manganese, sulfur, and phosphorus. Generally, the higher the carbon content in carbon steel, the greater the hardness and strength, but the lower the plasticity.
Classification
(1) According to the purpose, carbon steel can be divided into three categories: carbon structural steel, carbon tool steel and free-cutting structural steel. Carbon structural steel is further divided into engineering construction steel and machine manufacturing structural steel;
(2) According to the smelting method, it can be divided into open-hearth steel and converter steel;
(3) According to the deoxidation method, it can be divided into boiling steel (F), killed steel (Z), semi-killed steel (b) and special killed steel (TZ);
(4) According to the carbon content, carbon steel can be divided into low carbon steel (WC ≤ 0.25%), medium carbon steel (WC0.25%-0.6%) and high carbon steel (WC>0.6%);
(5) According to the quality of steel, carbon steel can be divided into ordinary carbon steel (high phosphorus and sulfur content), high-quality carbon steel (low phosphorus and sulfur content), high-grade high-quality steel (lower phosphorus and sulfur content) and special high-quality steel.
Types
Carbon structural steel
Grade: For example, Q235-A·F, indicating σs=235MPa.
Grade annotation: Q is yield strength, A is quality grade (there are four grades, ABCD), and F is boiling steel.
Features: low price, excellent process performance (such as weldability and cold formability).
Application: general engineering structures and ordinary mechanical parts. For example, Q235 can be used to make bolts, nuts, pins, hooks and less important mechanical parts, as well as threaded steel, steel sections, and steel bars in building structures.
High-quality carbon structural steel
Grade: For example, 45, 65Mn, 08F.
Grade annotation: directly indicates the ten thousandth of the metal carbon content.
Application: Non-alloy steel used to manufacture important mechanical parts is generally used after heat treatment.
Common steel grades and uses:
08F, low carbon mass fraction, good plasticity, low strength, used for stamping parts such as automobile and instrument housings;
20, good plasticity and weldability, used for parts with low strength requirements and carburized parts, such as hoods, welded containers, small shafts, nuts, washers and carburized gears;
45, 40Mn, good comprehensive mechanical properties after quenching and tempering, used for mechanical parts with large forces, such as gears, connecting rods, machine tool spindles, etc.;
60, 65Mn steel has high strength; used to manufacture various springs, locomotive wheel rims, and low-speed wheels.
Carbon tool steel
Grade: For example, T12 steel represents carbon tool steel with Wc=1.2%.
Grade annotation: T plus the thousandth of the metal carbon content.
Features: It belongs to eutectoid steel and hypereutectoid steel, with high strength and hardness, good wear resistance, and is suitable for manufacturing various low-speed cutting tools.
Common steel grades and uses:
T7, T8: Make parts that require toughness and withstand certain impact. Such as sledgehammers, punches, chisels, woodworking tools, scissors.
T9, T10, T11: Manufacture tools with low impact and high hardness and wear resistance. Such as taps, small drills, dies, hand saw blades.
T12, T13: Make tools that are not subject to impact. Such as files, scrapers, razors, and measuring tools.
Cast steel
Brand: For example, ZG200-400, which means cast steel with σs=200MPa and σb=400MPa.
Performance: The casting performance is worse than that of cast iron, but the mechanical properties are better than cast iron.
Application: Mainly used to manufacture relatively important mechanical parts with complex shapes, high mechanical properties, and difficult to form by forging and other methods in terms of technology, such as automobile gearbox housings, locomotive vehicle couplers and couplings, etc.