BS970 708M40 – High-Performance Low Alloy Steel
A Tough, Durable & Versatile Engineering Steel
BS970 708M40 is a high-strength, low-alloy steel renowned for its excellent tensile properties, impact resistance, and machinability. It is widely used in applications that demand shock resistance, wear durability, and structural integrity, making it an ideal choice for components under high stress and load.
Why Choose BS970 708M40?
- High Strength & Toughness – Tensile strength of 850-1000N/mm², ideal for demanding applications.
- Excellent Wear Resistance – Can be flame hardened or nitrided for maximum surface durability.
- Superior Machinability – Readily machinable in its hardened and tempered state, reducing production costs.
- Multiple Heat Treatment Options – Can be supplied in a softened state for custom hardening and tempering.
Material Characteristics & Properties
Mechanical Properties (Typical for Hardened & Tempered Condition)
- Tensile Strength: 850 – 1000 N/mm²
- Yield Strength: ~650 N/mm² (varies with heat treatment)
- Hardness (HB): 248 – 302
- Ductility & Impact Resistance: Excellent
Heat Treatment Options
Flame Hardening – Increases surface hardness, improving wear resistance and lifespan of components.
Nitriding – Provides exceptional abrasion resistance, making it ideal for high-wear applications.
Tempering & Hardening – Can be supplied in a softened state for custom heat treatments as required.
Material Condition: Untreated/ Annealed/ Quench and tempered
Surface Finish: As rolled/ As forged/ Bright drawn/ Bright turned
708M40 Steel Making
| C | Si | Mn | S | P | Cr | Ni* | Mo | |
| Min | 0.36 | 0.10 | 0.70 | 0.90 | 0.15 | |||
| Max | 0.44 | 0.35 | 1.00 | 0.040 | 0.035 | 1.20 | 0.40 | 0.25 |
(* Denotes residual element)
708M40 Typical Mechanical Properties
| Test Type | Tensile and hardness test (at room temperature} | Impact test (KV) | |||||||
| Yield (RE) | 0.2% Proof | UTS (Rm) | Elong (A) | R of A (Z) | Hardness | Room Temp | |||
| Unit | N/mm2 | N/mm2 | N/mm2 | % | % | HB | J | ||
| Annealed | Min | ||||||||
| Max | 235 | ||||||||
| Q + T + Drawn, condition 'T' | Min | 700 | 850 | 9 | 248 | 50 | |||
| Max | 1000 | 302 | |||||||
| Q + T to condition 'Q' | Min | 480 | 625 | 18 | 179 | 16 | |||
| Max | 775 | 229 | |||||||
| Q + T to condition 'R' | Min | 495 | 700 | 15 | 201 | 28 | |||
| Max | 850 | 255 | |||||||
| Q + T to condition 'S' | Min | 585 | 775 | 15 | 223 | 50 | |||
| Max | 925 | 277 | |||||||
| Q + T to condition 'T' | Min | 680 | 850 | 13 | 248 | 50 | |||
| Max | 1000 | 302 | |||||||
Ideal Applications for 708M40
This versatile engineering steel is commonly used in industries where high-load capacity, durability, and machinability are crucial. Typical applications include:
Automotive & Transportation
- Axle shafts
- Crankshafts
- High-strength gears
Industrial & Heavy Machinery
- Induction-hardened pins
- Hydraulic shafts
- Precision-machined components
General Engineering & Manufacturing
- Structural components
- Wear-resistant parts
- Load-bearing assemblies
Its adaptability makes it a go-to material for engineers looking for a balance of strength, wear resistance, and cost-effectiveness.
Stock Availability & Ordering
We supply BS970 708M40 in a variety of sizes and forms, including:
Hardened & Tempered Bars – Ready for immediate machining & installation
Softened Bars – Ideal for custom hardening and tempering
Custom Sizing & Heat Treatment Options Available
Call us on: 01902 341705
Email us at: enquiries@midlandbrightsteels.co.uk
Need Advice on Selection & Processing?
The team at Midland Bright Steels are happy to provide expert guidance to help you choose the right material and treatment process for your specific application.
