ISO C40E4 Alloy Steel Bar C40E4 Round Bars C40E4 Rods

Product Description

ISO C40E4 (1.1191) Steel Overview

ISO C40E4 is a high-quality medium-carbon engineering steel defined under the ISO 683-1 standard. The "E4" suffix indicates a specific degree of purity and controlled sulfur content, making it an upgraded version of standard C40. It is virtually identical to the well-known C45E or CK45 grades in terms of performance and chemical behavior.

This grade is favored for its high strength and consistent response to heat treatment, particularly induction or flame hardening.

Chemical Composition (%)

Mechanical Properties (Normalized)

Typical values for round bars in the normalized condition:

• Tensile Strength ($R_m$): $\ge$ 570 MPa

• Yield Strength ($R_e$): $\ge$ 330 MPa

• Elongation ($A_5$): $\ge$ 16%

• Hardness: ~170 - 210 HB

International Equivalents

ISO C40E4 is highly interchangeable with several major national standards:

Key Characteristics

1. Hardenability: It offers higher strength and hardness after heat treatment than lower carbon grades like C25 or C35. It can achieve a surface hardness of 54–57 HRC after hardening and tempering.

2. Machinability: In the annealed or normalized state, C40E4 provides good machinability, allowing for high-speed cutting and a good surface finish.

3. Forgeability: Excellent. It is a popular choice for drop forging and hot upsetting.

4. Weldability: Moderate to poor. Because of the higher carbon content, there is a risk of crack formation. Pre-heating to 200°C–300°C and post-weld stress relieving are strongly recommended.

Common Available Formats

• Round Bars: Available as hot-rolled, peeled, or cold-drawn. Used extensively for rotating parts and axles.

• Rods: Often used as starting material for forged components or high-strength fasteners.

• Forged Blocks: For heavy-duty machinery components.

Common Applications

• Mechanical Engineering: Crankshafts, steering knuckles, and gear racks.

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

• Tools: Hand tools like hammers, pliers, and wrenches.

• Power Transmission: Transmission shafts, hubs, and splines.

Thermal Processing Data

• Forging: 850°C – 1100°C.

• Normalizing: 840°C – 880°C.

• Annealing (Soft): 680°C – 710°C.

• Hardening: 820°C – 860°C (Quenching in water or oil).

• Tempering: 550°C – 660°C depending on the desired toughness.