Technical Report on EN-19 Carbon Steel
1. Introduction
EN-19 is a high-quality alloy steel grade predominantly known for its excellent mechanical properties. It belongs to the class of medium carbon, low alloy steel and is commonly referred to by its AISI designation 4140. With its combination of strength, toughness, and wear resistance, EN-19 is widely used in engineering applications where durability under dynamic loads is crucial.
2. Chemical Composition
The typical chemical composition of EN-19 steel is as follows:
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.36 – 0.44 |
| Silicon (Si) | 0.10 – 0.35 |
| Manganese (Mn) | 0.50 – 0.80 |
| Chromium (Cr) | 0.90 – 1.50 |
| Molybdenum (Mo) | 0.15 – 0.30 |
| Sulfur (S) | ≤ 0.035 |
| Phosphorus (P) | ≤ 0.035 |
3. Mechanical Properties
EN-19 can be heat-treated to achieve a wide range of mechanical properties:
| Property | Value (typical, heat-treated) |
|---|---|
| Tensile Strength | 850 – 1000 MPa |
| Yield Strength | ~680 MPa |
| Hardness (HRC) | 28 – 32 |
| Elongation (%) | ~13 – 16 |
| Impact Toughness | High |
| Modulus of Elasticity | ~210 GPa |
4. Heat Treatment Processes
EN-19 responds well to a variety of heat treatment processes:
- Normalizing: Refines grain structure, improves machinability.
- Hardening and Tempering: Enhances strength and toughness.
- Annealing: Improves ductility and reduces hardness for machining.
- Case Hardening: Surface hardening while maintaining core toughness.
5. Key Properties
- High Tensile Strength
- Good Ductility and Toughness
- Excellent Wear Resistance
- High Fatigue Strength
- Good Machinability in Annealed Condition
- Good Response to Heat Treatment
6. Applications in Engineering Industry
EN-19 is extensively used across various sectors of the engineering industry:
6.1 Automotive Industry
- Gears, crankshafts, axles
- Drive shafts and differential shafts
- Connecting rods and camshafts
6.2 Aerospace Industry
- Landing gear components
- Actuator shafts and levers
- High-strength fasteners
6.3 Oil & Gas and Heavy Machinery
- Drill collars, tool joints
- Hydraulic machinery components
- Shafts under dynamic stress
6.4 Power Generation
- Turbine shafts
- High-load mechanical couplings
6.5 General Engineering
- Machine tool spindles
- Studs, bolts, and high-strength fasteners
- Heavy-duty gearboxes and power transmission systems
7. Fabrication and Welding
EN-19 steel is machinable in the annealed condition. However, due to its alloying content and high hardenability, pre-heating is recommended before welding to avoid cracking. Post-weld heat treatment (PWHT) is often required to relieve residual stress.
8. Conclusion
EN-19 carbon steel is a versatile alloy widely recognized for its excellent mechanical performance and adaptability to various industrial applications. Its ability to undergo significant heat treatment and deliver high strength-to-weight ratios makes it a material of choice for dynamically loaded components in the automotive, aerospace, and general engineering sectors.
9. References
- ASM Handbook on Alloy Steels
- ISO 683-1: Heat-treated steels, alloy steels and free-cutting steels
- British Standard BS970: EN19
