CSN 12040 Alloy Steel Bar 12040 Round Bars 12040 Rods

Product Description

CSN 12040 is a Czech standard (ÄŒSN) high-quality medium-carbon structural steel. It is the equivalent of the widely used European C40 or C45 grades. This steel is designed for components that require higher strength and hardness than mild steel, making it one of the most common materials for general mechanical engineering.

1. Chemical Composition

The "12" prefix in the CSN system denotes structural carbon steels, and "040" indicates the carbon content (approximately 0.40%).

2. Mechanical Properties

Its properties vary significantly depending on whether the bar is in a normalized or a quenched and tempered (QT) state.

3. Key Technical Characteristics

• Surface Hardening: CSN 12040 is ideal for induction or flame hardening. This allows the part to have a very hard, wear-resistant surface (up to 50–55 HRC) while maintaining a ductile core.

• Machinability: Very high. It is a preferred grade for complex CNC turning and milling because it produces consistent chips and a smooth surface finish.

• Weldability:Poor to Moderate. Due to the 0.40% carbon content, it is susceptible to cracking. Preheating to 200°C and slow cooling are required if welding is necessary.

• Forging: Excellent. It is easily hot-worked at temperatures between 850°C and 1100°C.

4. Global Equivalents

CSN 12040 is essentially the Czech version of the "Workhorse" carbon steels used globally:

5. Common Applications

CSN 12040 round bars and rods are used for parts where moderate stress and wear resistance are required:

• Shafts & Axles: Crankshafts, transmission shafts, and axle journals.

• Gears & Pinions: Medium-load gears (often induction hardened).

• Fasteners: High-strength bolts, studs, and heavy-duty nuts.

• General Parts: Spindles, levers, hubs, and connecting rods for pumps and compressors.

Available Stock Conditions

• Round Bars: Available from 8mm up to 500mm+.

• Rods: Often available as hot-rolled (black) or cold-drawn (calibrated) with h9/h11 tolerances.

• Finish: Can be supplied as "Peeled" to remove the decarburized surface layer, which is essential if you plan to surface-harden the material.