Key Properties
Chemical Composition: Low carbon content (≤0.12%), with manganese (0.30-0.60%) and trace elements; sulfur and phosphorus are strictly controlled (≤0.045%) for better toughness.
Mechanical Performance: Yield strength ≥195MPa, tensile strength 315-430MPa, elongation ≥30%. It has excellent plasticity, weldability, and cold-forming ability (e.g., easy bending, rolling).
Typical Applications
Structural uses: Scaffolding tubes, frame supports, and lightweight structural frameworks in construction.
Low-pressure fluid transport: Water, air, or gas pipelines where high pressure resistance is not required.
Daily necessities: Fencing, handrails, and simple metal components in furniture or agricultural equipment.

Properties: Carbon content 0.14-0.22%, tensile strength 375-500MPa, elongation ≥26%; excellent weldability and formability, but the "A" grade has no impact toughness requirements.
Applications: Construction scaffolding, low-pressure fluid pipes (water, gas), machinery frames, and other general structures or medium-low load scenarios.
Features: Easy to process, low cost, suitable for general needs in non-extreme environments.

Composition: Carbon (0.18-0.28%), manganese (0.50-0.80%), with sulfur/phosphorus ≤0.050% each.
Mechanicals: Tensile strength 490-630MPa, elongation ≥20%. It balances higher strength with moderate formability and weldability.
Applications
Medium-stress structural parts: Frames, supports, and load-bearing tubes in machinery, construction, and automotive industries.
Low-pressure industrial pipelines: Transporting fluids or gases where higher strength than Q235 is needed.

Chemical Composition: Carbon (C ≤0.08%), manganese (Mn ≤0.40%), silicon (Si ≤0.03%), with strict limits on sulfur (S ≤0.035%) and phosphorus (P ≤0.035%) for high purity.
Mechanical Performance: Tensile strength 270-390 MPa, yield strength ≤185 MPa, elongation ≥35%. It is extremely malleable, enabling deep drawing, bending, and precise shaping without cracking.
Typical Applications
Fine cold-formed products: Thin-walled tubes for precision instruments, decorative pipes, and small-diameter tubes in household appliances.
Low-pressure, lightweight uses: Fluid transport tubes in non-critical systems (e.g., water lines for small appliances) and structural tubes requiring a smooth surface finish.

Chemical Composition: Carbon (C: 0.07-0.14%), manganese (Mn: 0.35-0.65%), with low sulfur (≤0.035%) and phosphorus (≤0.035%).
Mechanical Performance: Tensile strength 335-475 MPa, yield strength ≥205 MPa, elongation ≥25%. It balances moderate strength with high ductility.
Typical Applications
Fluid transport: Pipelines for water, gas, oil, or steam in low-to-medium pressure systems (e.g., industrial pipelines, automotive fuel lines).
Mechanical parts: Fabricated components like sleeves, connectors, and structural tubes requiring easy welding/forming.

Chemical Composition: Carbon (C: 0.17-0.24%), manganese (Mn: 0.35-0.65%), with strict limits on sulfur (≤0.035%) and phosphorus (≤0.035%).
Mechanical Performance: Tensile strength 410-550 MPa, yield strength ≥245 MPa, elongation ≥22%. It offers higher strength than 10# steel while maintaining good ductility.
Typical Applications
Pressure piping: Used in low-to-medium pressure fluid transport systems, such as water, steam, oil, and gas pipelines in power plants, chemical factories, and heating systems.
Mechanical manufacturing: Fabrication of structural parts, fittings, and seamless tubes for machinery, automotive, and hydraulic equipment.

Chemical Composition: Carbon (C: 0.27-0.34%), manganese (Mn: 0.50-0.80%), with sulfur (≤0.035%) and phosphorus (≤0.035%) to ensure basic purity.
Mechanical Performance: Tensile strength 500-650 MPa, yield strength ≥295 MPa, elongation ≥17%. Its higher carbon content contributes to greater strength and hardness, though ductility is lower than low-carbon grades.
Typical Applications
Mechanical structural parts: Used in the fabrication of shafts, gears, connecting rods, and high-strength structural tubes for machinery, where moderate load-bearing capacity is required.
Medium-stress components: Suitable for parts in automotive, hydraulic, and industrial equipment that need to withstand higher static or dynamic loads.
Non-critical pressure scenarios: Occasionally used in low-pressure pipelines where strength takes priority over extreme ductility.

Composition: Carbon (0.52-0.60%), manganese (0.50-0.80%), with strict sulfur/phosphorus limits (≤0.035% each).
Mechanicals: Tensile strength ≥645MPa, yield strength ≥380MPa, elongation ≥13%. Hardness reaches 217-255HB (annealed/untreated), with enhanced wear resistance after heat treatment.
Applications
High-stress components: Gears, shafts, and structural tubes in machinery requiring strength and wear resistance.
Industrial tools: Frames or parts for cutting/forming equipment, where hardness is critical.

20Mn is a low-alloy manganese steel tube/pipe with ~0.20% carbon and 1.10-1.40% manganese, stronger than plain low-carbon steels.
Properties: Tensile strength 450-600MPa, yield strength ≥275MPa, elongation ≥20%. Good weldability and machinability.
Applications: Machinery frames, shafts, automotive parts, and medium-pressure fluid pipes needing higher strength than ordinary low-carbon steels.