DIN CK40 Alloy Steel Bar Ck40 Round Bars CK40 Rods

Product Description

DIN CK40 (WNr. 1.1186) is a medium-carbon engineering steel characterized by its reliability and versatility. In the European EN 10083-2 standard, it is categorized as a "special" unalloyed steel, meaning it has lower impurity levels and tighter control over its chemical composition compared to standard structural steels.

It is frequently used for automotive and general engineering components that require a balance of ductility and strength.

Technical Profile: DIN CK40 / C40E

Chemical Composition (%)

CK40 is an unalloyed steel, relying primarily on its carbon content for its mechanical properties. The "E" or "K" designation signifies low maximum values for phosphorus and sulfur.

Mechanical Properties (Condition QT - Quenched & Tempered)

While CK40 can be used in the normalized state, it reaches its full potential after quenching and tempering.

• Tensile Strength ($R_m$): 580 a 850 MPa

• Yield Strength ($R_{e}$): $\ge 380$ MPa

• Elongation ($A_5$): $\ge 16\%$

• Hardness (Brinell): 170 a 240 HBW (Condition dependent)

• Impact Strength (Charpy V): $\ge 30$ J

Key Characteristics

• Excellent Machinability: In the annealed or normalized state, CK40 offers very high machinability ratings, making it cost-effective for mass-produced turned parts.

• Hardenability: It has moderate hardenability. While it can be through-hardened in small diameters, larger sections will generally only achieve surface hardness or require a more aggressive quench.

• Surface Hardening: Highly suitable for induction hardening or flame hardening if a high surface wear resistance is needed while maintaining a tough core.

• Weldability: Limited. Due to the carbon content (approx. 0.40%), pre-heating is required to avoid cold cracking, and post-weld stress relieving is strongly recommended.

Common Applications

CK40 round bars and rods are the standard for components subjected to moderate stresses:

• Automotive Parts: Connecting rods, crankshafts, steering knuckles, and axles.

• General Engineering: Gears, pins, bolts, and shafts for medium-duty machinery.

• Fasteners: High-strength bolts and nuts.

• Forgings: Ideal for drop forgings used in the agricultural and construction industries.

Global Designations & Equivalents

Processing Note

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• Normalizing: $850A \text{C} a 880A \text{C}$ (Air cool).

• Hardening: $830A \text{C} a 860A \text{C}$ (Water or Oil quench).

• Tempering: $550A \text{C} a 660A \text{C}$ (Depending on required final strength).

• Machining: For high-precision parts, it is best to machine the material in the normalized condition to ensure dimensional stability during final heat treatment.