Ck45 Steel Billet/Bar: The Versatile Medium Carbon Grade
Ck45 is a common, unalloyed medium carbon steel defined by the European standard EN 10083 (often referenced by its older designation, C45). It is one of the most widely used general-purpose engineering steels globally, known primarily for its balance of strength, moderate ductility, and suitability for heat treatment. This grade is recognized worldwide, being directly comparable to the American standard AISI 1045.
The designation “Ck” in some specifications indicates that the steel has a low controlled sulphur and phosphorus content, ensuring a cleaner steel with better mechanical properties and response to heat treatment. Ck45 is supplied both as semi-finished billets and as finished bars (hot-rolled, forged, or cold-drawn).
ERST Group supplies Ck45 billets and bars, meeting the high-volume requirements of the general machinery and manufacturing industries.
Key Characteristics and Performance
Ck45 is primarily used when moderate strength and hardness are required, often achieved through simple normalizing or quenching and tempering.
Key Characteristics
- Moderate Strength: Offers good tensile strength and yield strength, typically higher than low-carbon steels like ST37.
- Heat Treatable: Excellent response to quenching and tempering (Q+T) to achieve required hardness levels for specific applications.
- Good Machinability: In the normalized or soft annealed condition, Ck45 exhibits good machinability.
- Weldability: While weldable, its medium carbon content requires preheating and post-weld heat treatment to avoid cold cracking, especially in thicker sections.
Primary Applications
- Shafts and Axles: Used extensively for moderately stressed shafts, axles, and gear blanks.
- Machine Parts: Couplings, bolts, connecting rods, rolls, and various general engineering components.
- Forgings: Highly utilized for forged parts requiring subsequent heat treatment for improved strength.
- Tools: Simple hand tools and machinery components where abrasion is not extreme.
Standard Chemical Composition (EN 10083 / Ck45 Equivalent)
The chemical composition is centered around a carbon content of approximately 0.45%, which is critical for its mechanical properties after heat treatment.
Ck45 Steel Chemical Specification
| Element | Specification (%) | Role of the Element |
|---|---|---|
| Carbon (C) | 0.42 – 0.50 | Defines the grade; crucial for hardness after heat treatment. |
| Silicon (Si) | 0.10 – 0.40 | Deoxidizer; improves cast structure and strength. |
| Manganese (Mn) | 0.50 – 0.80 | Increases strength and improves response to heat treatment. |
| Phosphorus (P) | Max 0.035 | Impurity; strictly controlled for low brittleness. |
| Sulphur (S) | Max 0.035 | Impurity; strictly controlled for better machinability and toughness. |
| Chromium (Cr) | Max 0.40 | Residual element; generally controlled below alloying levels. |
Forms and Delivery
Ck45 is offered in several formats based on the required stage of manufacturing.
- Billet: Semi-finished product (e.g., $100 \times 100$ mm to $150 \times 150$ mm) for rolling into smaller bars or forging.
- Round/Flat Bar: Finished product, supplied either Hot-Rolled (HR) or Cold-Drawn (CD). Cold-drawn bars offer tighter dimensional tolerance and better surface finish.
- Condition: Typically supplied in the Normalized or Annealed condition to optimize machinability before final processing by the end-user.
- Packaging: Bars and billets are bundled and strapped with steel banding for bulk and secure handling.