AFNOR XC18 Alloy Steel Bar XC18 Round Bars XC18 Rods

Product Description

AFNOR XC18 (WNr. 1.0401) is a low-carbon engineering steel characterized by its excellent ductility and superior weldability. In the French AFNOR system, it is the standard "case-hardening" grade (acier pour cACmentation).

Because of its low carbon content, it is primarily used for components that require a hard, wear-resistant surface but must retain a very tough, shock-resistant core to withstand impact.

Technical Profile: AFNOR XC18

Chemical Composition (%)

XC18 is a clean, unalloyed carbon steel. Its low carbon level ensures it remains soft and workable before the case-hardening process.

Mechanical Properties (As Rolled/Normalized)

In its base state, XC18 focuses on formability rather than raw strength.

• Tensile Strength ($R_m$): 410 a 540 MPa

• Yield Strength ($R_e$): $\ge 235$ MPa

• Elongation ($A_5$): $\ge 22\%$

• Hardness (Brinell): ~130 a 170 HBW

• Case Hardness: Can reach 58 a 62 HRC after carburizing and quenching.

Key Characteristics

• Exceptional Weldability: Due to its low carbon equivalent, XC18 can be welded without the need for pre-heating or post-weld heat treatment in most applications, making it ideal for welded assemblies.

• Carburizing Grade: It is specifically designed to absorb carbon into its surface layer during heat treatment. This creates a "case" that is extremely hard while the "core" remains ductile.

• Formability: XC18 is very easy to cold-work, bend, and forge. It is often used for parts that require significant shaping before final hardening.

• Machinability: Very good machinability in the normalized or as-rolled condition. It does not "gum" as much as ultra-low carbon steels but is softer than medium-carbon grades like XC42.

Common Applications

XC18 round bars and rods are utilized for small-to-medium parts subjected to high surface wear:

• Mechanical Links: Pins, bushings, and pivots.

• Automotive Parts: Camshafts (case-hardened), gear shifters, and levers.

• Fasteners: Specialized bolts and rivets that require toughness.

• General Engineering: Spindles, light-duty gears, and spacers in machinery.

Global Designations & Equivalents

Heat Treatment & Processing

• Normalizing: $890A \text{C} a 920A \text{C}$ (Air cool).

• Carburizing (Case Hardening): Typically performed at $880A \text{C} a 980A \text{C}$ in a carbon-rich environment.

• Core Refinement: $880A \text{C} a 910A \text{C}$ followed by water or oil quenching.

• Case Hardening Quench: $780A \text{C} a 820A \text{C}$ (Water or Oil).

• Tempering: $150A \text{C} a 200A \text{C}$ to relieve internal stresses without significantly reducing surface hardness.