BS 080M40 Alloy Steel Bar 080M40 Round Bars 080M40 Rods

Product Description

BS 080M40 (En8) Steel Overview

BS 080M40, widely known by its older designation En8, is a medium-carbon unalloyed steel. It is one of the most frequently used grades in general engineering due to its versatility, providing higher strength than mild steel while remaining relatively easy to machine and treat.

It is governed by the BS 970 standard and is categorized as a "through-hardening" steel, meaning it can be heat-treated to improve mechanical properties across its entire cross-section.

Technical Specifications (Typical)

Chemical Composition (%)

International Equivalents

080M40 is the British standard designation that aligns with several other major global grades:

Key Characteristics

1. Machinability: Excellent. In its normalized or as-rolled condition, it is a favorite for high-speed machining and turning.

2. Heat Treatment Response: It can be surface hardened to approximately 50–55 HRC via induction or flame hardening, making it suitable for parts requiring wear resistance.

3. Weldability: Moderate. Because of the carbon content, it is more susceptible to cracking than mild steel. Pre-heating to 150°C–250°C is recommended, followed by slow cooling.

4. Toughness: Offers a good balance of ductility and strength, though it is not as tough as alloyed steels like 4140 (En19).

Common Available Formats

• Round Bars: Available as Bright Drawn (for precision and smooth finish) or Black Hot Rolled (for general forging and heavy machining).

• Rods: Often used for manufacturing high-strength studs, long-threaded bars, and small-diameter pins.

• Hexagon & Square Bars: Frequently stocked for the production of nuts, bolts, and specialized fittings.

Common Applications

• Automotive: Axles, spindles, steering arms, and brake cylinders.

• General Engineering: Shafts, gears, rockers, and stressed pins.

• Fasteners: High-tensile bolts, studs, and heavy-duty screws.

• Tools: Standard hand tools like spanners and basic wrenches.

Thermal Processing Data

• Forging: 850°C – 1200°C.

• Normalizing: 830°C – 860°C.

• Annealing: 680°C – 710°C (Slow furnace cool).

• Hardening: 820°C – 860°C (Quench in Water or Oil).

• Tempering: 550°C – 660°C to achieve the desired toughness.