4140 Alloy Structural Steel / DIN 1.7225 / JIS SCM440
4140 is a medium-carbon, low-alloy structural steel enhanced through a sophisticated balance of chromium (Cr) and molybdenum (Mo) elements. It represents not merely the accumulation of individual elements, but the crystallisation of scientific alloying. This unique composition endows it with a foundation of comprehensive properties surpassing ordinary carbon steel, establishing it as the ‘core muscle’ across numerous industrial sectors.
Product Description
Xiri Tool Steel is a leading supplier of 4140 alloy structural steel (DIN 1.7225) in China. 4140 alloy steel is a chromium-molybdenum alloy structural steel, which features excellent strength, toughness and hardenability. It is widely used in mechanical manufacturing for parts that require high strength, wear resistance and fatigue resistance.
Whether you need 4140 flat bars, 1.7225 steel plates, or forged rounds, we provide custom dimensions with machining or grinding services. Our materials are strictly tested to ensure premium metallurgical structure.
4140 is a medium-carbon, low-alloy structural steel enhanced through a sophisticated balance of chromium (Cr) and molybdenum (Mo) elements. It represents not merely the accumulation of individual elements, but the crystallisation of scientific alloying. This unique composition endows it with a foundation of comprehensive properties surpassing ordinary carbon steel, establishing it as the ‘core muscle’ across numerous industrial sectors.
Chemical Composition of 4140 / DIN 1.7225 tool steel
| C | Si | Mn | Cr | P | S | Mo |
| 0.38-0.43 | max 0.40 | 0.60-0.90 | 0.90-1.20 | max 0.035 | max 0.035 | 0.15-0.30 |
Supply Form & Size Range of 4140 / DIN 1.7225 tool steel
We supply 4140 / DIN 1.7225 steel in various forms to meet your manufacturing needs:
Round bar: Diameter 16mm – 1000mm
Steel Plate / Flat: Thickness 16mm – 1000mm x Width 200mm – 2200mm
Surface: Black, Peeled, Rough machined or Grinded.
Delivery Condition: Annealed (Hardness 217 HB max.)
Exceptional Performance of 4140 / DIN 1.7225 Alloy Steel | The Cornerstone of Reliability
A Perfect Balance of High Strength and Toughness: The core value of 4140 steel lies in its outstanding strength combined with excellent toughness. Following standard quenching and tempering heat treatment, it withstands immense impact loads without sudden fracture, providing robust safety assurance for critical equipment.
Superior Fatigue Strength and Wear Resistance: Frequent stress cycles are the nemesis of many components. 4140 significantly extends the service life of moving parts such as gears, shafts, and connectors through its outstanding fatigue resistance. Its surface hardness and wear resistance also rank among the highest in steels of comparable strength, effectively countering performance degradation caused by abrasion.
Superior Quenchability Guaranteed: The core advantage of chromium-molybdenum alloying lies in substantially enhanced quenchability. This ensures uniform high strength and toughness even across larger cross-sections (up to approximately 100mm thickness), guaranteeing no performance shortcomings in large or complex components.
Broad process adaptability: 4140 demonstrates excellent machining flexibility. Whether undergoing machining (turning, milling, drilling, grinding), welding (with appropriate preheating and post-weld heat treatment), forging, or heat treatment, it exhibits outstanding adaptability, facilitating manufacturers in realising complex designs and efficient production.
4140 Alloy Structural Steel Applications
Power Transmission and Mechanical Core Components: High-performance gears (transmissions, drive systems), drive shafts, camshafts, connecting rods, universal joints, critical bolts, and other high-stress, high-cycle-load components.
Hydraulics and Fluid Control: High-pressure cylinders, pump bodies, valve blocks (requiring precise heat treatment to ensure sealing surface integrity), etc., relying on its strength and sealing reliability.
Energy and Heavy Equipment: Drilling rig components (drill collars, joints), wear-resistant parts for mining machinery, critical load-bearing structural elements in construction equipment (e.g., excavator pins), and large-scale equipment frames.
Moulds and Tooling: Plastic mould inserts, extrusion dies, and wear-resistant tooling fixtures requiring high strength and toughness.
Precision Components and Special Applications: Aerospace structural components (subject to stricter certification), high-end bicycle parts (frame components, forks), and load-bearing medical device components (e.g., operating table joints, support rods).
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.
