42CrMo4 Steel Billet/Bar: High-Strength Chromium-Molybdenum Steel
42CrMo4 is a high-performance, medium-carbon alloy steel widely specified in European (EN 10083) and international standards. It is one of the most common grades in the Chromium-Molybdenum (Cr-Mo) series, often considered the European equivalent to the widely used AISI 4140 steel.
This steel grade is primarily supplied as billets (semi-finished) or as hot-rolled/forged bars (finished product). Its chemical composition is tailored to achieve superior strength, toughness, and fatigue resistance, particularly after heat treatment (quenching and tempering).
ERST Group specializes in sourcing and supplying 42CrMo4 in various forms (billets and bars), meeting the stringent demands of the machinery, automotive, and oil & gas industries.
Key Characteristics and Performance
The addition of Chromium (Cr) and Molybdenum (Mo) is what defines this alloy, giving it exceptional mechanical properties.
Key Characteristics
- High Hardenability: The Cr-Mo combination significantly increases the depth to which the steel can be effectively hardened during quenching.
- Excellent Strength and Toughness: After proper heat treatment (Quenching and Tempering), 42CrMo4 achieves a high balance of tensile strength, yield strength, and impact toughness.
- High Fatigue Resistance: Essential for moving parts subjected to cyclical loading, such as shafts and gears.
- Good Wear Resistance: Suitable for components operating under abrasive conditions.
Primary Applications
- Automotive: Axles, crankshafts, connecting rods, heavy-duty gear systems, and steering components.
- Machinery: High-strength fasteners, shafts, coupling elements, and highly stressed parts in machine tools.
- Oil & Gas: Drill collars, wellhead equipment, and high-pressure valves.
- General Engineering: Gears, sprockets, and heavy construction pins.
Standard Chemical Composition (EN 10083 Equivalent)
The chemical composition is tightly controlled to ensure uniform response to heat treatment and reliable mechanical performance.
42CrMo4 Steel Chemical Specification
| Element | Specification (%) | Role of the Element |
|---|---|---|
| Carbon (C) | 0.38 – 0.45 | Provides high strength after hardening. |
| Chromium (Cr) | 0.90 – 1.20 | Increases hardenability and corrosion resistance. |
| Molybdenum (Mo) | 0.15 – 0.30 | Prevents temper brittleness and maintains high-temperature strength. |
| Silicon (Si) | Max 0.40 | Deoxidizer; residual element. |
| Manganese (Mn) | 0.60 – 0.90 | Increases strength and improves hot workability. |
| Phosphorus (P) | Max 0.035 | Impurity; must be minimized. |
| Sulphur (S) | Max 0.035 | Impurity; must be minimized. |
Forms and Delivery
42CrMo4 is versatile and supplied in various forms depending on the final application.
- Billet: Semi-finished square cross-sections (e.g., $100 \times 100$ mm to $150 \times 150$ mm) used for subsequent rolling or forging.
- Round Bar/Flat Bar: Finished products, usually hot-rolled, forged, or sometimes cold-drawn, and often supplied in the heat-treated condition (Quenched and Tempered – QT).
- Packaging: Bars are supplied in bundles, strapped securely with steel banding. Billets are shipped in bulk bundles, optimized for cargo integrity.