4140 Steel DIN Equivalent – Full Guide to Standards, Chemistry, and Applications
When sourcing steel internationally, understanding the 4140 steel DIN standard equivalent is crucial. Engineers, buyers, and manufacturers often face confusion when comparing AISI, SAE, DIN, and EN standards. Choosing the wrong grade can lead to costly project delays or product failures. This article gives you a comprehensive look at DIN 42CrMo4, the European counterpart to AISI 4140, covering its chemical composition, mechanical properties, heat treatment response, and real-world applications.
🔍 What Is the DIN Equivalent of 4140 Steel?
The direct 4140 steel DIN equivalent is 42CrMo4, which also goes by the EN designation 1.7225. These steels are chromium-molybdenum low-alloy steels with similar chemical balance and mechanical performance. In most applications, they are interchangeable as long as the specified heat treatment condition is respected.
| Standard | Grade | Description |
|---|---|---|
| AISI/SAE | 4140 | Cr-Mo low-alloy steel |
| DIN | 42CrMo4 | Cr-Mo low-alloy steel |
| EN | 1.7225 | European norm designation |
| JIS | SCM440 | Japanese equivalent grade |
This table highlights how 4140 steel international equivalents allow global manufacturers to source comparable materials from different markets.
🧪 Detailed Chemical Composition
Both AISI 4140 and DIN 42CrMo4 contain chromium, molybdenum, and carbon as key strengthening elements. Their close chemistry provides high hardenability and toughness.
| Element | 42CrMo4 (DIN) | 4140 (AISI) | Function |
| Carbon (C) | 0.38 – 0.45% | 0.38 – 0.43% | Increases hardness & strength |
| Chromium (Cr) | 0.90 – 1.20% | 0.80 – 1.10% | Improves wear resistance, hardenability |
| Molybdenum (Mo) | 0.15 – 0.30% | 0.15 – 0.25% | Adds high-temperature strength |
| Manganese (Mn) | 0.60 – 0.90% | 0.75 – 1.00% | Boosts toughness |
| Silicon (Si) | 0.10 – 0.40% | 0.15 – 0.35% | Improves strength, deoxidizes steel |
| Sulfur (S) | ≤0.035% | ≤0.040% | Affects machinability |
Because the chemistry is so close, 4140 steel DIN equivalent chemistry allows engineers to swap grades with minimal adjustments.
⚙️ Mechanical Properties According to DIN
The 4140 steel mechanical properties DIN specifications show high strength and toughness, particularly when quenched and tempered.
| Property | Normalized (N) | Quenched & Tempered (Q&T) |
| Tensile Strength | 850 – 1000 MPa | 1080 – 1230 MPa |
| Yield Strength | ~650 MPa | 900+ MPa |
| Elongation | 14 – 16% | 12 – 14% |
| Impact Toughness | >35 J | >30 J |
| Hardness (HB) | 197 – 235 | 248 – 302 |
This combination of strength and ductility makes 42CrMo4 DIN steel equivalent to 4140 an excellent choice for parts that experience shock loading, like crankshafts and gears.
🔥 Heat Treatment Response
One of the reasons why 4140 steel DIN equivalent is so popular is its excellent response to heat treatment:
- Annealing: Produces machinable structure with hardness around 200 HB.
- Quenching & Tempering: Can achieve 28–32 HRC or higher depending on tempering temperature.
- Induction Hardening: Surface hardness up to 55 HRC for wear resistance.
This flexibility allows engineers to tailor the steel’s properties for specific applications, from heavy-duty shafts to precision tooling.
🏭 Real-World Applications
Because of its combination of strength, toughness, and wear resistance, 4140 steel DIN standard equivalent (42CrMo4) is widely used in demanding industries:
- Automotive & Transportation – axles, crankshafts, steering knuckles, gears
- Oil & Gas – drill collars, tool joints, couplings, high-stress components
- Mining & Construction – pins, bushings, hydraulic shafts, wear plates
- Machine Building – spindles, rollers, dies, fixtures
- Defense & Aerospace – landing gear, support arms, weapon components
These applications highlight why understanding 4140 steel DIN 42CrMo4 comparison is essential for global sourcing.
📦 Sourcing Tips for Buyers
- Confirm the delivery condition (N, Q&T) to ensure mechanical properties meet requirements.
- Request mill test certificates (MTC) to verify chemical composition.
- Consider machining allowances if ordering hot rolled material.
- Work with a supplier that offers cutting and heat treatment services to save processing time.
🌟 Company Advantages
At Otai Special Steel, we stock large quantities of 4140 steel DIN equivalent (42CrMo4 / 1.7225) from 6mm to 300mm thickness. Our advantages:
- ✅ Over 10,000 tons in ready-to-ship inventory
- ✅ UT-tested plates to guarantee internal soundness
- ✅ Precision cutting, heat treatment, and CNC machining services
- ✅ Support for SGS, BV, or customer-appointed inspections
- ✅ Fast worldwide shipping and competitive pricing
Our goal is to help you source exactly the grade you need, with minimal risk and maximum efficiency.
❓ FAQ
Q1: Can I replace 4140 with 42CrMo4 in my project?
A: Yes, they are equivalent grades, but always check heat treatment specs and mechanical requirements before substitution.
Q2: What is the difference between DIN 42CrMo4 and EN 1.7225?
A: There is no practical difference — EN 1.7225 is simply the European Norm designation for the same steel.
Q3: How do I know if my supplier is giving me the correct material?
A: Request MTC with chemical composition and mechanical test results to verify compliance with DIN or AISI standards.
Q4: Is there a cheaper alternative to 4140 steel?
A: Some projects can use lower alloy steels like 1045 or 4130, but you must confirm if the lower strength and hardenability are acceptable.
Q5: Can 42CrMo4 be welded?
A: Yes, but preheating and post-weld stress relief are recommended to prevent cracking.
