Chemical Composition: It has a low carbon content (typically ≤0.12%), along with small amounts of manganese, silicon, sulfur, and phosphorus, ensuring good weldability and formability.
Applications: Commonly used in manufacturing general structural parts, such as brackets, pipes, containers, automotive components, and everyday hardware. It is also suitable for low-stress structural applications due to its cost-effectiveness.

Chemical Composition: Low carbon content (≤0.22%), with trace elements like manganese, silicon, sulfur, and phosphorus (sulfur ≤0.050%, phosphorus ≤0.045% for Q235-A).
Applications:
Ideal for general structural uses such as building frames, bridges, machinery parts, containers, and automotive components. It is cost-effective and suitable for low-to-medium stress scenarios.

Chemical Composition: Contains slightly higher carbon (typically 0.18-0.28%) and manganese, contributing to its enhanced strength. Sulfur and phosphorus content are controlled (≤0.050% each) for basic workability.
Applications:
Suitable for structural components requiring higher strength, such as machinery parts, brackets, gears, and medium-stress industrial structures. It balances cost and performance for applications beyond the scope of lower-strength carbon steels.

Chemical Composition: Ultra-low carbon content (≤0.08%), with minimal manganese and silicon, ensuring high purity and uniformity.
Applications:
Ideal for manufacturing thin-walled, complex-shaped parts requiring precise forming, such as automotive body panels, household appliance casings, food cans, and metal containers. It is also used in decorative metal products due to its good surface finish after processing.

Chemical Composition: Low carbon (0.07-0.14%), with small amounts of manganese (0.35-0.65%) and trace elements like silicon, sulfur, and phosphorus (strictly controlled for purity, with sulfur ≤0.035% and phosphorus ≤0.035%).
Applications:
Widely used in manufacturing parts requiring good plasticity and weldability, such as pipes, containers, bolts, nuts, and mechanical components (e.g., shafts, gears) that do not bear heavy loads. It is also suitable for cold-forming processes and can be carburized to enhance surface hardness for specific uses.

Chemical Composition:
Carbon (C): 0.17-0.24% (slightly higher than 10# steel, contributing to higher strength).
Manganese (Mn): 0.35-0.65%.
Silicon (Si): ≤0.30%.
Sulfur (S) and phosphorus (P): Strictly controlled (≤0.035% each), ensuring good purity and workability.
Applications
20# steel plate/sheet is versatile, suitable for both structural and functional components requiring moderate strength and formability:
General structures: Frames, brackets, and low-to-medium stress parts in machinery.
Pressure-containing components: Pipes, boilers, and containers (for non-high-pressure scenarios).
Carburized parts: Shafts, gears, and fasteners (surface carburizing enhances wear resistance while maintaining core toughness).
Cold-formed products: Stamped parts, automotive components, and hardware.

30# is a medium-carbon high-quality structural steel with ~0.30% carbon, stronger than 10#/20#.
Properties: Yield strength ≥295 MPa, tensile strength 540-660 MPa; moderate ductility (elongation ≥20%) and workability (welding needs preheating).
Uses: Medium-load parts like shafts, gears, bolts; suitable for heat treatment to enhance hardness.
Note: Balances strength and processability, fit for medium-stress applications.

Chemical Composition: Carbon (C) 0.52 - 0.60%, silicon (Si) 0.17 - 0.37%, manganese (Mn) 0.50 - 0.80%, sulfur (S) ≤0.035%, phosphorus (P) ≤0.035%, chromium (Cr) ≤0.25%, nickel (Ni) ≤0.30%, copper (Cu) ≤0.25%.
Applications: It is widely used in the manufacture of wear - resistant and high - strength mechanical parts such as gears, connecting rods, and locomotive wheel tires in the mechanical manufacturing field; in the metallurgical and mining fields, it is used to make various equipment; in the transportation field, it is used to make structural parts such as automobile frames and suspension systems.

20Mn is a high-quality structural steel containing manganese, with a carbon content of approximately 0.20% and a manganese content of 1.20-1.60% (higher than ordinary carbon steel).
Properties: Yield strength ≥345MPa, tensile strength 510-650MPa, elongation ≥18%; good weldability, and hardenability better than ordinary carbon steel.
Applications: Suitable for mechanical manufacturing (shafts, gears, etc.), medium-load structural parts in automobiles and heavy machinery, and can be cold-formed.
Features: Manganese enhances strength and hardenability, offering high cost-effectiveness. It has higher strength than 20# steel while maintaining good plasticity.