4340 Alloy Structural Steel / DIN 1.6582 / JIS SNCM8
4340 is a specially engineered nickel-chromium-molybdenum alloy structural steel. Through precise control of the ratios of core elements such as chromium, nickel, and molybdenum, it achieves comprehensive properties surpassing conventional steels. Its core appeal lies in striking a perfect balance between high strength and exceptional toughness, making it an ideal choice for withstanding heavy loads, impacts, and complex stresses.
Product Description
Xiri Tool Steel is a leading supplier of 4340 alloy steel (DIN 1.6582) in China. 4340 steel is a nickel-chromium-molybdenum alloy structural steel, featuring extremely high strength, toughness and hardenability. It is widely used in key components of aviation, military industry and heavy-duty machinery that demand extremely high comprehensive mechanical properties.
Whether you need 4340 flat bars, 1.6582 steel plates, or forged rounds, we provide custom dimensions with machining or grinding services. Our materials are strictly tested to ensure premium metallurgical structure.
4340 is a specially engineered nickel-chromium-molybdenum alloy structural steel. Through precise control of the ratios of core elements such as chromium, nickel, and molybdenum, it achieves comprehensive properties surpassing conventional steels. Its core appeal lies in striking a perfect balance between high strength and exceptional toughness, making it an ideal choice for withstanding heavy loads, impacts, and complex stresses.
Equivalent Grades of 4340 Alloy Steel
| USA SAE |
Germany DIN |
Japan JIS |
ISO | China GB |
Russia GOST |
| 4340 | 1.6582 | SNCM439 | 35NiCrMo6 | 40CrNiMoA | 40ХН2МА |
Chemical Composition of 4340 Alloy Steel
| C | Si | Mn | Cr | P | S | Mo | Ni |
| 0.38-0.43 | 0.15-0.35 | 0.60-0.80 | 0.70-0.90 | max 0.030 | max 0.030 | 0.20-0.30 | 1.65-2.00 |
Supply Form & Size Range of 4340 Alloy Steel
We supply 4340 alloy steel in various forms to meet your manufacturing needs:
Round bar: Diameter 16mm – 1000mm
Steel Plate / Flat: Thickness 16mm – 1000mm x Width 200mm – 1800mm
Surface: Black, Peeled, Rough machined or Grinded.
Delivery Condition: Annealed (Hardness 248 HB max.)
Exceptional Performance of 4340 Alloy Steel | Building Competitive Advantage
Superior Strength and Toughness: Following appropriate heat treatment, 4340 steel exhibits remarkable high strength while maintaining outstanding impact toughness and fracture toughness. This effectively resists stress concentration and unexpected impacts, significantly reducing the risk of critical component failure and ensuring stable equipment operation.
Superior Quenchability: Benefiting from an optimised alloy composition, 4340 exhibits exceptional hardenability. This ensures uniform hardening from core to surface even in large-section or complex-shaped components, guaranteeing consistent mechanical properties throughout. This meets the stringent demands of large, critical components.
Superior Fatigue Strength: Under conditions involving repeated alternating loads, 4340 steel demonstrates outstanding fatigue resistance. This is crucial for power transmission components undergoing prolonged operation and structural elements subjected to cyclic stresses, significantly extending service life while reducing maintenance downtime frequency and associated costs.
Excellent Machinability and Heat Treatment Adaptability: Despite its high strength, 4340 retains good machinability in the annealed condition. Crucially, its full performance potential is unlocked through quenching and tempering (normalising), allowing flexible adjustment of final hardness and toughness levels to suit diverse application requirements.
4340 Alloy Steel Applications
Aerospace: Aircraft landing gear, critical drive shafts, engine crankshafts – relying on 4340’s strength and toughness to ensure flight safety.
Oil and Energy: Drilling tools (drill collars, adaptor joints), large oilfield equipment components, power turbine shafts – withstanding extreme pressures and impacts.
High-end Moulds: Hot-work moulds, plastic mould cores, ejector pins, etc. – performing reliably in high-temperature, high-pressure environments.
Automotive and Heavy Machinery:
High-performance transmission gears, shafts, connecting rods, and high-strength fasteners enhance powertrain reliability and efficiency.
Defence Industry:
Armoured vehicle components and critical artillery assemblies safeguard national defence assets.
Precision Instruments and General Machinery:
Heavy-duty spindles, gears, and camshafts ensure long-term stable operation of precision equipment.
Our advantages in Processing 4340 Alloy Steel
Recognising that material stability and consistency directly impact your product performance and reputation, we implement rigorous end-to-end quality control for 4340 alloy structural steel:
Source Control: Selecting premium raw materials and strictly executing advanced smelting techniques such as vacuum degassing to ensure molten steel purity while controlling harmful elements and inclusions.
Precise Composition: Employing techniques like spectral analysis, we meticulously monitor and adjust the composition of each steel batch to ensure alloy element content strictly meets standard requirements.
Non-Destructive Testing: Utilising advanced methods such as ultrasonic testing, we conduct non-destructive inspections on rolled bars and forgings to effectively identify and eliminate internal defects, guaranteeing material integrity.
Heat Treatment Specialists:
Relying on precise heat treatment equipment and processes (accurate temperature control, atmosphere protection), we ensure each batch of material achieves stable, consistent quenched and tempered microstructure and properties.
Full Traceability:
Establishing a comprehensive quality tracking system ensures traceability at every stage from smelting and processing to final delivery, providing you with peace of mind.
Not sure about the best equivalent for your application?
Why Manufacturers Choose Huangshi Xiri
Huangshi Xiri combines international-standard steel grades, a complete tool steel portfolio, strict quality control and reliable global supply. We match DIN / JIS / AISI equivalents precisely, offer cutting and heat-treatment services, and control every step from smelting to inspection. With stable capacity, on-time delivery and responsive technical support, we help manufacturers reduce risk, save costs and run production with confidence.
Contact Us
Contact Huangshi Xiri today for quotations, grade selection and technical support on tool steel, mold steel and alloy steel. Whether you need samples, cutting-to-size service or long-term supply for your projects, our engineers and sales team are ready to respond quickly with professional advice and reliable solutions for your manufacturing needs.
