EN31

EN31 Alloy Steel Product Overview

EN31, also known as 535A99 or AISI 52100, is a high-carbon, chromium-containing alloy steel known for its excellent hardness, wear resistance, and fatigue strength. Standardised under BS 970, it is primarily used for applications requiring high load-bearing capacity and resistance to abrasive wear, such as bearings and high-precision components. EN31 offers deep and uniform hardening, high compressive strength, and good dimensional stability, typically supplied in the annealed condition (max 229 HB) or hardened and tempered (58–62 HRC). Its high chromium content provides moderate corrosion resistance, making it suitable for demanding engineering applications.

Applications

EN31 alloy steel is widely used in industries requiring durable, high-wear components:

Bearings:

• Ball and roller bearings for automotive, aerospace, and industrial machinery.
• High-precision bearing races and rolling elements.

Engineering Components:

• Gears, shafts, and spindles subjected to high wear and stress.
• Punches, dies, and forming tools for cold work applications.
• Camshafts, tappets, and other automotive components.

Other Uses:

• Precision gauges, measuring tools, and wear-resistant machine parts.
• Cold forging dies and high-load bushings.
• Components in heavy machinery, railways, and defence applications.

Chemical Composition

The chemical composition of EN31 ensures its high hardness, wear resistance, and strength:

• Chromium (Cr): Enhances hardness, wear resistance, and moderate corrosion resistance.
• Carbon (C): Provides high hardness and strength, ideal for bearing applications.
• Silicon (Si) and Manganese (Mn): Improve strength and hardenability, though present in low amounts.

Supply Size

EN31 alloy steel is available in various forms and sizes to meet industrial requirements:

• Round Bars:
  Diameter 16 mm to 700 mm.
• Flat Bars:
  Minimum: 10 mm thickness x 80 mm width.
  Maximum: 500 mm thickness x 2000 mm width.