40Cr4 alloy steel

Introduction

We manufacture forging ingots, billets, and blooms in alloy steel specifically for 40cr4, tailored for engineering and automotive applications.

40Cr4 is a medium carbon, chromium alloy steel known for its good strength, reliable toughness, and wear resistance. It is designed to perform under moderate to high mechanical loads and is widely used in automotive components, machinery parts, and general engineering applications.

The chromium content improves hardenability, allowing uniform heat treatment response and enhanced wear resistance. 40Cr4 also offers good machinability in the annealed condition and maintains dimensional stability after heat treatment, making it suitable for forging and precision machining processes.

This steel provides a balanced combination of mechanical performance, durability, and cost effectiveness for industrial applications.

Chemical composition

Element	Content (%)	Function / effect
Carbon (c)	0.38 – 0.45	Provides hardness and strength
Manganese (mn)	0.60 – 0.90	Improves hardenability and toughness
Silicon (si)	0.15 – 0.35	Increases strength and elasticity
Chromium (cr)	0.90 – 1.20	Increases hardness and wear resistance
Phosphorus (p)	Max 0.035	Impurity; lower content improves toughness
Sulphur (s)	Max 0.035	Impurity; controlled for machinability

Mechanical properties (typical, depending on condition & heat treatment)

• Tensile strength: 750 – 950 MPa
• Yield strength: 550 – 700 MPa
• Hardness: 24 – 32 HRC (customizable)
• Impact toughness: Good
• Fatigue resistance: Good

Heat treatment

• annealing: used to soften the steel for improved machinability before final processing.
• quenching: heating to approximately 830 – 860°c followed by rapid cooling to obtain required hardness.
• tempering: reheating to relieve internal stresses and improve toughness while maintaining hardness.

The heat treatment process can be adjusted to achieve the desired balance of strength and toughness.

Key features and benefits

• through hardening capability: uniform hardness across the section
• good strength and toughness: suitable for moderate to high load applications
• good wear resistance: improves component service life
• good machinability in annealed condition: ease of manufacturing
• dimensional stability: reduced distortion after heat treatment
• suitable for forging and machining: flexible processing options

Typical applications

• shafts and axles
• gears and pinions
• automotive components
• forged engineering parts
• couplings and general machine parts

Equivalent steel grades

• 40Cr4 has several international equivalents, including:
• 41Cr4 – higher strength chromium steel
• En18 (bs en 10083-1) – european standard alloy steel
• aisi 5140 – american standard

Why choose 40Cr4 for your application?

40Cr4 offers a reliable balance of strength, toughness, and cost efficiency. Its good hardenability, machinability, and dimensional stability make it suitable for a wide range of engineering and automotive components subjected to moderate to high stress.

Comparison table for similar grades

Grade	Carbon (%)	Key applications	Heat treatment	Comments
40cr4	0.38 – 0.45	Shafts, gears, automotive parts	Quenching & tempering	Balanced strength and toughness
41Cr4	0.38 – 0.45	Heavy-duty shafts, gears	Quenching & tempering	Higher hardenability
En18	0.35 – 0.45	General engineering, shafts	Quenching & tempering	Widely used alloy steel
Aisi 5140	0.38 – 0.43	Automotive, gears, shafts	Quenching & tempering	American equivalent

Summary

40Cr4 is a medium carbon chromium alloy steel suitable for quenching and tempering applications in engineering and automotive industries. It delivers dependable mechanical performance, durability, and value for general-purpose high-stress components.