AFNOR 20MC5 Alloy Steel Bar 20MC5 Round Bars 20MC5 Rods

Product Description

AFNOR 20MC5 is a French standard chromium-manganese alloy steel designed primarily for case-hardening (carburizing). It is the slightly higher-carbon sibling to the 16MC5 grade, offering increased core strength while maintaining the excellent surface hardness required for heavy-duty mechanical parts.

1. Chemical Composition

The "20" denotes a carbon content of approximately 0.20%, while "MC" indicates the alloying elements Manganese (M) and Chromium (C).

2. Mechanical Properties (Post Heat Treatment)

When quenched and tempered (specifically after carburizing the surface), 20MC5 exhibits high fatigue strength and wear resistance.

• Tensile Strength ($R_m$): 900 – 1200 MPa

• Yield Strength ($R_e$):$\ge$ 650 MPa

• Elongation ($A_5$):$\ge$ 9%

• Surface Hardness: 59 – 63 HRC (after case hardening)

• Core Hardness: Typically 300 – 400 HB

3. Technical Characteristics

• Hardenability: 20MC5 has high hardenability due to the Manganese and Chromium combination, allowing for consistent results even in medium-sized cross-sections.

• Carburizing Capability: It is specifically formulated to absorb carbon into its outer layer at temperatures between 880°C and 980°C.

• Ductility: Even with a high-strength core, it retains sufficient toughness to withstand shock loads and vibrations in drivetrain applications.

• Machinability: Best machined in the soft-annealed (+A) or treated-to-hardness (+TH) condition.

4. Global Equivalents

20MC5 is the AFNOR (French) equivalent of the widely used European grade 20MnCr5.

5. Common Applications

This grade is a staple in the automotive and heavy machinery industries for parts that face high surface pressure and friction:

• Power Transmission: High-load gears, crown wheels, and pinions.

• Engine Components: Camshafts, piston pins, and crankshaft gears.

• Mechanical Engineering: Heavy-duty splined shafts, bushings, and universal joint components.

• Tools: High-strength bolts and guide pins.

Supply Information

• Forms: Round bars, rods, and forgings.

• Condition: Typically supplied as hot-rolled (black surface) or cold-drawn (bright surface).

• Heat Treatment State: Most suppliers provide this in a normalized or annealed state so that you can machine it before your final hardening process.