BS970 817M40T / EN24T – High-Performance Alloy Steel
Versatile, Strong & Wear-Resistant for Demanding Applications
BS970 817M40T / EN24T is a high-strength, Nickel-Chromium-Molybdenum alloy steel renowned for its exceptional wear resistance, toughness, and machinability. This material is widely used across industries requiring through-hardened components that must endure high stress, impact, and wear conditions.
Why Choose 817M40T / EN24T?
High Tensile Strength & Toughness – Excellent performance under dynamic and impact loading.
Superior Wear Resistance – Designed to withstand abrasion and fatigue, ideal for moving components.
Excellent Machinability – Readily machineable in the hardened and tempered “T” condition.
Flexible Supply Options – Available in bright drawn, turned, hot rolled, and forged block form.
Custom Sizing – Forged blocks can be cold sawn to exact dimensions, reducing machining time.
Material Characteristics & Properties
Mechanical Properties (Typical in Hardened & Tempered “T” Condition)
- Tensile Strength: 850 – 1000 N/mm²
- Yield Strength: 680 N/mm² (approx.)
- Hardness (HB): 248 – 302
- Ductility: High, ensuring good elongation and impact resistance
Heat Treatment Options
Through Hardening – Achieves uniform strength and wear resistance throughout the component.
Tempering – Enhances toughness while maintaining hardness, making it suitable for high-stress applications.
Forged Block Availability – Cold sawn to custom sizes, reducing material waste and processing costs.
Ideal Applications for 817M40T / EN24T
This alloy steel is a trusted choice in precision engineering due to its ability to withstand high loads, wear, and shock forces. It is commonly used in:
Automotive & Motorsport
- Axles
- Gears
- Drive shafts
Heavy Machinery & Construction
- High-load pins
- Structural studs
- Precision-engineered fasteners
Aerospace & Engineering
- Aircraft landing gear components
- Wear-resistant machine parts
- Custom-fabricated industrial tools
Its strength, durability, and processing flexibility make it one of the most widely used engineering steels in high-performance applications.
Stock Availability & Ordering
We supply BS970 817M40T / EN24T in a variety of forms and sizes, including:
Bright Drawn, Turned & Hot Rolled Bars – Ready for immediate machining & use
Forged Blocks – Available for custom cold sawing to specific dimensions
Custom Heat Treatment Options Available
Call us on: 01902 341705
Email us at: enquiries@midlandbrightsteels.co.uk
Need Help Selecting the Right Material?
Our team is happy to provide technical guidance to ensure you choose the best steel grade for your application.
817M40T / EN24T
| BS970: 1955 | BS970: 1991 | Description |
| EN24T | 817M40T | Bright/Black 1.1/2% nickel chromium molybdenum steel |
| Chemical Analysis | |
| Car | 0.36/0.44 |
| Si | 0.10/0.40 |
| Mang | 0.45/0.70 |
| Phos | 0.035 max |
| Sul | 0.040 max |
| Moly | 0.20/0.35 |
| Nick | 1.30/1.70 |
| Mechanical Properties | |
| Tensile Strength N/MM2 Min Rm | 850/1000 |
| Yield Stress NIMM2 Min Rm | 700 |
| Elongation A Min% on 5.65√SO | 9 |
| Izod Min | 54 |
| Kcv Min | - |
| Proof Stress 0.2% N/MM2 Min | 680 |
| Brinell Hardness | 248/302 |
| International Specification Comparison | |
| BS 970:1991 | 817M40T |
| BS 970: 1955 | EN24T |
| German Din | 34NiCrMo6 |
| French Afnor | 35NCD6 |
| Swedish SS | 2541 |
| American SAE | 4340 |
| European Steel No | 1.6582 |
| European Steel Name | 34CrNiMo6 |
| European Standard | EN10277-5 |
| Quick View System | |
| Machineability | 40 |
| Weldability | Pre / post heat precaution required |
| Hardenability | High strength up to 100mm dia |
| Selection Guide and Usage Examples | Popular direct hardening steel with good tensile. ductility, shock and wear resistance properties |
| Size Range Summary | ||
| Rounds | IMP | 3/8" -3" dia |
| MM | 10mm -310mm dia | |
