When it comes to engineering steels that combine high tensile strength, toughness, wear resistance, and heat-treatability, few materials stand out as much as EN19 / 42CrMo4 Alloy Steel. Widely recognized for its durability and performance in demanding applications, EN19 steel is one of the most trusted chromium-molybdenum alloy steels in the market.

Whether you’re designing automotive shafts, heavy-duty gears, aerospace landing components, or oilfield tools, EN19 (709M40) / 42CrMo4 / AISI 4140 / JIS SCM440 offers the right blend of strength and machinability.

What is EN19 / 42CrMo4 Alloy Steel?

EN19 is a high tensile alloy steel defined under BS 970 (709M40), while 42CrMo4 is its European EN equivalent. Both belong to the chromium-molybdenum alloy steel family, which is widely recognized for excellent mechanical performance and heat-treatment adaptability.

Key Highlights:

• Medium-carbon, chromium-molybdenum steel
• Excellent fatigue strength under dynamic loads
• Superior toughness & wear resistance
• High hardenability with proper quenching and tempering
• Suitable for precision-machined components

It is often compared with AISI 4140 alloy steel, another globally popular equivalent.

Learn more about our Alloy Steel Products.

Chemical Composition of EN19 / 42CrMo4

The chemical makeup gives this steel its unique characteristics:

This balanced composition ensures high tensile strength, toughness, and wear resistance. Chromium enhances corrosion and oxidation resistance, while molybdenum improves hardenability and creep resistance.

Mechanical Properties of EN19 Alloy Steel

The properties of EN19 / 42CrMo4 vary with heat treatment, but typically:

These properties make it a multi-purpose alloy steel for both heavy-duty and precision applications.

Strength of EN19 / 42CrMo4 Steel

One of the biggest reasons EN19 is so popular is its strength-to-weight ratio. Unlike mild steels, it retains high tensile and fatigue strength, making it suitable for:

• High-load automotive parts
• Rotating shafts & gears
• Aerospace-grade forgings
• Oilfield drilling equipment

Its hardness can be tailored via heat treatment, allowing manufacturers to optimize components for wear resistance or toughness.

Heat Treatment of EN19 / 42CrMo4

Heat treatment is the defining factor in unlocking EN19’s full potential.

1. Annealing
   
   
   • Process: Heated to 680–700°C and furnace cooled
   • Purpose: Improves machinability and refines grain structure
      
2. Normalizing
   
   
   • Process: Heated to 850–900°C, air cooled
   • Purpose: Improves mechanical uniformity
      
3. Hardening (Quenching)
   
   
   • Process: Heated to 840–880°C, quenched in oil/water
   • Purpose: Increases hardness & tensile strength
      
4. Tempering
   
   
   • Process: Heated to 540–680°C
   • Purpose: Balances hardness and toughness, reduces brittleness
      
5. Nitriding / Carburizing
   
   
   • Process: Case hardening
   • Purpose: Increases surface hardness and wear resistance

Related Reading: AISI 4140 Alloy Steel Heat Treatment Guide.
 

Industrial Applications of EN19/42CrMo4 Steel

1. Automotive Industry

• Axles, crankshafts, gears, spindles
• High-performance fasteners and bolts

2. Oil & Gas Sector

• Drill collars, tool joints, couplings
• High-pressure tubing and downhole tools

3. Aerospace & Defense

• Aircraft landing gear components
• Armored vehicle drivetrain parts

4. Power Generation & Heavy Engineering

• Turbine shafts
• Generator and motor components

5. General Machinery

• Machine tool mandrels and spindles
• Forged and machined components requiring durability

Check out our Steel Weight Calculator to estimate EN19 steel part weights accurately.

Advantages of EN19 / 42CrMo4 Alloy Steel

Disadvantages of EN19 / 42CrMo4 Alloy Steel

Equivalent Grades of EN19 / 42CrMo4

This interchangeability makes it globally available and reliable.

Conclusion

EN19 / 42CrMo4 Alloy Steel is one of the most versatile and high-performing engineering steels available today. With its high tensile strength, wear resistance, and adaptability to heat treatment, it finds use in automotive, aerospace, oil & gas, and heavy engineering sectors.

Whether you need components that resist fatigue, handle high torque, or withstand extreme conditions, EN19 / 42CrMo4 is a proven choice.

At Nifty Alloys, we stock and supply EN19, 42CrMo4, and equivalent alloy steels in different forms including round bars, plates, and forgings, ensuring quality and reliability for your projects.