40CrNi2MoA Alloy Structural Steel / SAE 4340 / DIN 1.6511
40CrNi2MoA alloy structural steel is a high-strength nickel-chromium-molybdenum steel with excellent toughness, deep hardenability, fatigue resistance, and stable mechanical performance after heat treatment. It is widely used in heavy-duty shafts, gears, aerospace parts, landing gear components, and other critical load-bearing applications that require high strength, impact resistance, and long service life.
Product Description
Xiri Tool Steel is a leading supplier of 40CrNi2MoA alloy structural steel in China. 40CrNi2MoA is a high-strength alloy structural steel. Due to its content of approximately 1.7% to 2.0% nickel and 0.2% to 0.3% molybdenum, it features extremely high strength and toughness, as well as excellent hardenability. This steel is often used in the manufacturing of high-load critical parts such as heavy machinery shafts, turbine shafts for aircraft engines, and gears. However, it should be noted that its weldability is relatively poor, and preheating treatment is required before welding.
Whether you need 40CrNi2MoA flat bars, steel plates, or forged rounds, we provide custom dimensions with machining or grinding services. Our materials are strictly tested to ensure premium metallurgical structure.
40CrNi2MoA (also known as AISI 4340 modified grade) is a classic medium-carbon, nickel-chromium-molybdenum ultra-high-strength alloy structural steel. It is no ordinary steel, but rather the culmination of material science and metallurgical engineering expertise. Through a meticulously balanced elemental composition, it achieves an optimal equilibrium of strength, toughness, and ductility.
Carbon (C): Provides fundamental strength and hardness.
Chromium (Cr): Enhances hardenability, wear resistance, and corrosion resistance.
Nickel (Ni): Significantly improves low-temperature toughness and strength, crucial for withstanding impact loads.
Molybdenum (Mo): Effectively prevents high-temperature temper brittleness, refines grain structure, and further enhances strength and hardenability.
This scientifically engineered alloy system renders 40CrNi2MoA the material of choice for manufacturing critical load-bearing structural components, proving irreplaceable in applications subjected to immense stress and impact.
Chemical Composition of 40CrNi2MoA steel
| C | Si | Mn | Cr | P | S | Ni | Mo |
| 0.37-0.44 | 0.17-0.37 | 0.50-0.80 | 0.60-0.90 | ≤0.025 | ≤0.025 | 1.80-2.10 | 0.20-0.30 |
Supply Form & Size Range of 40CrNi2MoA steel
We supply 40CrNi2MoA 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 or QT
Core Performance of 40CrNi2MoA Alloy Structural Steel
- The perfect fusion of ultra-high strength and superior toughness: This represents 40CrNi2MoA’s most fundamental advantage. Following appropriate heat treatment, its tensile strength can readily exceed 1000MPa, and even surpass this threshold. More remarkably, it maintains outstanding impact toughness alongside this high strength, effectively avoiding the brittleness often associated with high-strength materials. This prevents sudden fracture under extreme loads.
- Exceptionally deep hardenability: This ensures uniform, high mechanical properties throughout the core and surface, even in large-section components after heat treatment. Regardless of your component’s dimensions, it guarantees outstanding strength and toughness from the surface to the core, overcoming the challenges posed by structural thickness.
- Superior fatigue strength: Under alternating loads, 40CrNi2MoA demonstrates exceptional fatigue resistance, significantly extending component lifespan under cyclic stresses. This is crucial for dynamically loaded components such as engine crankshafts and aircraft landing gear.
- Good Processability: It offers satisfactory forging and machining properties. Regarding welding, it demonstrates good weldability when appropriate preheating and post-heating processes are employed, facilitating the manufacture of complex structures.
Core Application of 40CrNi2MoA Alloy Structural Steel
Leveraging its comprehensive properties, 40CrNi2MoA serves as the backbone across numerous demanding industrial sectors:
Aerospace: Aircraft landing gear, critical connectors, engine drive shafts, helicopter rotor systems. Here, its performance reaches its zenith, where safety and reliability reign supreme.
Defence and Military: Transmission components for tanks and armoured vehicles, gun mounts, axles and suspension systems for heavy vehicles – forming the robust backbone safeguarding national security.
Energy and Heavy Machinery: Bucket linkages for large excavators, drill pipe joints for oil drilling, large turbine drive shafts, critical load-bearing components for wind power equipment – standing firm under heavy loads and harsh conditions.
High-End Moulding: For manufacturing large-scale, precision, long-life plastic moulds and die-casting moulds, ensuring production efficiency and product quality.
High-Performance Racing & Specialised Vehicles: Key motion components such as drive shafts, connecting rods, and crankshafts provide lightweight, high-strength solutions for pursuing ultimate speed and performance.
Our advantages in Processing 40CrNi2MoA Alloy Structural Steel
We understand that a material’s theoretical properties can only be realised through rigorous production control and quality management. For premium steels like 40CrNi2MoA, we have established a comprehensive, end-to-end quality assurance system.
- Source Control, Selecting Raw Materials: We rigorously select raw materials to guarantee the purity and precise composition of the steel from its origin.
- Precision Smelting, Pure Steel Quality: Employing advanced Electric Arc Furnace (EAF) smelting + Ladle Refining (LF/VD/VOD) technology, we effectively control gas content (e.g., hydrogen, oxygen), significantly reduce non-metallic inclusions, and enhance steel purity. This forms the foundation for ensuring high toughness and fatigue life.
- Intelligent Controlled Rolling and Cooling for Optimised Microstructure: Through controlled rolling and cooling processes, we refine austenite grain size and optimise the material’s internal microstructure, laying the groundwork for superior comprehensive properties during subsequent heat treatment.
- Full-process heat treatment to unlock performance potential: Our specialised heat treatment lines subject every batch of 40CrNi2MoA to quenching and tempering, including high-temperature tempering. Precise control of heating temperatures, soaking times, and cooling rates ensures optimal matching of strength, hardness, and toughness to customer specifications.
- Comprehensive Inspection, Data-Driven Assurance:
Chemical Composition Analysis: Employing direct-reading spectrometers to guarantee precise composition accuracy for every furnace of molten steel.
Mechanical Properties Testing: Conducting full sets of mechanical tests—including tensile, impact, and hardness assessments—on each batch, accompanied by authoritative inspection reports.
Non-destructive testing: Employing techniques such as ultrasonic testing, we conduct 100% internal inspection of steel to ensure freedom from internal defects including cracks, white spots, and shrinkage cavities.
High-magnification microstructure examination: Analysing material microstructure via metallographic microscopy guarantees compliance with stringent standards.
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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.
