En31 alloy steel

Introduction

we manufacture forging ingots, billets, and blooms in alloy steel specifically for En31, tailored for high-performance applications.  

En31 is a high carbon, high chromium alloy steel renowned for its exceptional hardness, wear resistance, and excellent fatigue strength. It is primarily designed for applications where extreme surface hardness and long service life are critical. Due to its high carbon and chromium content, En31 achieves very high hardness after heat treatment, making it a preferred material for bearing and tooling applications.

This grade provides superior resistance to abrasion and fatigue wear, ensuring long-lasting performance in demanding environments. Its high hardenability allows for uniform hardness throughout the component, which is essential for precision parts used in automotive, industrial machinery, and tooling industries.

Chemical composition

Element	Content (%)	Function / effect
Carbon (c)	0.90 – 1.20	Provides very high hardness and wear resistance
Manganese (mn)	0.30 – 0.75	Improves hardenability and strength
Sulphur (s)	Max 0.050	Controlled for machinability
Phosphorus (p)	Max 0.050	Impurity; low content improves toughness
Silicon (si)	0.10 – 0.35	Increases strength and elasticity
Chromium (cr)	1.00 – 1.60	Greatly improves hardenability, wear resistance, and hardness
Nickel (ni)	Nil	Not present
Molybdenum (mo)	Nil	Not present

Mechanical properties (typical values after hardening & tempering)

• Tensile strength:  very high (application dependent)
• Hardness:  58 – 65 hrc (after proper heat treatment)
• Wear resistance:  excellent
• Impact toughness:  moderate
• Fatigue resistance:  very good

Heat treatment

• Annealing:  used to soften the steel for machinability before final heat treatment
• Hardening:  heating to approx. 800 – 850°c followed by oil quenching
• Tempering:  low-temperature tempering to relieve internal stresses while maintaining high hardness

Proper heat treatment  is critical to achieve optimum performance and avoid brittleness.

Key features and benefits

• Very high hardness and excellent wear resistance
• High chromium content provides good hardenability
• Excellent fatigue life under rolling and contact stress
• Good dimensional stability after heat treatment
• Suitable for precision grinding and finishing
• Ideal for components requiring long service life

Typical applications

• Ball and roller bearings
• Bearing races and rings
• Dies and tools
• Spindles and guide rollers
• Measuring tools and gauges
• Other high wear and high contact-stress components

Equivalent steel grades

• En31 (bs 970):  british standard
• AISI  52100:  american bearing steel
• 100cr6 (en iso 683-17):  european equivalent
• Din 1.3505:  german standard

Why choose En31 for your application?

En31 is the preferred choice where extreme hardness, wear resistance, and fatigue performance are required. Its high carbon–high chromium composition makes it ideal for bearing and precision tooling applications where reliability and long service life are essential.

Comparison table for similar grades

Grade	Carbon (%)	Key applications	Heat treatment	Comments
En31	0.90-1.20	Bearings, dies, races	Hardening & tempering	Very high hardness & wear resistance
100cr6	0.95-1.05	Bearing components	Hardening & tempering	European equivalent
Aisi 52100	0.95-1.10	Bearings & races	Hardening & tempering	American equivalent

Summary

En31 is a high carbon chromium alloy steel optimized for hardened and ground components subjected to severe wear and contact stresses. It delivers outstanding hardness, wear resistance, and fatigue performance in demanding industrial applications.