DIN 17200 C22 Structural Steel

Introduction

DIN 17200 is a part of the German Industrial Standards (DIN) for technical delivery conditions of steel and related products. DIN 17200 C22 specifies the chemical composition, mechanical properties, heat treatment, and weldability requirements for C22 structural steel. C22 steel is a high-quality carbon structural steel with good strength, ductility, and weldability, making it suitable for a wide range of structural applications.

Chemical Composition

The chemical composition range of C22 steel is as follows:

  • Carbon (C): 0.17 – 0.24%
  • Manganese (Mn): 0.3 – 0.6%
  • Silicon (Si): ≤0.4%
  • Phosphorus (P): ≤0.045%
  • Sulfur (S): ≤0.045%
  • Lead (Pb): ≤0.33% (optional)

Carbon is the primary strengthening element in steel. Manganese increases the strength and hardenability of steel. Silicon improves the strength and ductility of steel. Phosphorus and sulfur reduce the strength and ductility of steel and increase its brittleness. Lead reduces the machinability and weldability of steel.

Mechanical Properties

The mechanical properties of C22 steel depend on its heat treatment condition. In the annealed state, the typical mechanical properties of C22 steel are as follows:

  • Ultimate tensile strength (σb): ≤156 MPa
  • Yield strength (σs): –
  • Elongation at break (δ): –
  • Reduction in area (ψ): –
  • Brinell hardness (HB): ≤130

In the quenched and tempered state, the typical mechanical properties of C22 steel are as follows:

  • Ultimate tensile strength (σb): 550 – 700 MPa
  • Yield strength (σs): ≥350 MPa
  • Elongation at break (δ): ≥20%
  • Reduction in area (ψ): ≥40%
  • Brinell hardness (HB): 190 – 260

Heat Treatment

Common heat treatment processes for C22 steel include annealing, normalizing, and tempering.

  • Annealing: Annealing is a heat treatment process in which the steel is heated to above its recrystallization temperature and then slowly cooled. Annealing relieves residual stresses in the steel, softens the steel, and makes it easier to machine.
  • Normalizing: Normalizing is a heat treatment process in which the steel is heated to above its Ac1 temperature (usually slightly above the recrystallization temperature of the steel) and then cooled in air. Normalizing refines the grain structure of the steel, improving its strength and ductility.
  • Tempering: Tempering is a heat treatment process in which the steel is heated to a specific temperature below its Ac1 temperature, held for a period of time, and then cooled in air. Tempering further improves the ductility of the steel and reduces its hardness and brittleness.
DIN 17200 C22 Structural Steel Coils

Weldability

C22 steel has good weldability. However, the following should be considered when welding:

  • Preheating: Before welding, the steel should be preheated to 150 – 200 °C to reduce welding stresses and the risk of cracking.
  • Electrode selection: Welding electrodes should be selected that match the chemical composition of the base metal.
  • Welding process: The correct welding process should be used, such as low-hydrogen electrodes or inert gas shielded welding, to avoid welding defects.
  • Post-weld heat treatment: After welding, the steel should be tempered to relieve welding stresses and improve ductility.

Applications

C22 steel is suitable for a wide range of structural applications, including:

  • Construction: C22 steel can be used to fabricate building structures such as beams, columns, and trusses.
  • Mechanical manufacturing: C22 steel can be used to manufacture machine parts such as gears, shafts, and connecting rods.
  • Transportation: C22 steel can be used to manufacture transportation vehicles such as trucks, trailers, and railway vehicles.

Comparison with Other Standards

C22 steel has the following advantages compared to other similar structural steels:

  • Compared to ASTM A36 steel, C22 steel has higher strength and ductility.
  • Compared to GB Q235 steel, C22 steel has better weldability.

Conclusion

C22 steel is a versatile structural steel with good strength, ductility, and weldability, making it suitable for a wide range of structural applications. C22 steel is widely used in industries such as construction. Contact us for more!

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