4140 Steel Number – Understanding DIN 1.7225 and International Material Standards
When engineers, buyers, and machinists search for 4140 steel number, they usually want to identify the equivalent international material designation for this popular chromium-molybdenum alloy steel. Known for its high strength, toughness, wear resistance, and heat treatment performance, 4140 steel is widely used in machinery manufacturing, oil and gas equipment, automotive components, and industrial tooling.
The most recognized steel number for 4140 steel is:
| Standard | Material Grade | Steel Number |
|---|---|---|
| DIN / EN | 42CrMo4 | 1.7225 |
| AISI / SAE | 4140 | G41400 |
| ASTM | A29 4140 | G41400 |
| JIS | SCM440 | — |
| GB | 42CrMo | — |
Many global buyers also compare 4140 alloy steel, 42CrMo4 steel, SCM440 steel, and 42CrMo material because these grades share very similar chemical composition and mechanical properties.
🔍 What Is 4140 Steel?
4140 steel is a medium-carbon chromium-molybdenum alloy steel with excellent hardenability and fatigue strength. The material performs extremely well in demanding applications requiring:
- High tensile strength
- Good impact resistance
- Wear resistance
- Heat treatment stability
- Excellent toughness
Because of its balanced alloy composition, 4140 steel can be supplied in multiple conditions, including:
- Annealed
- Normalized
- Pre-hardened
- Quenched and tempered
This flexibility makes the material highly popular for high-strength alloy steel applications.
🧪 Chemical Composition of 4140 Steel
The chemical composition of 4140 steel gives the material its excellent mechanical performance and heat treatment response.
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.38 – 0.43 |
| Silicon (Si) | 0.15 – 0.35 |
| Manganese (Mn) | 0.75 – 1.00 |
| Chromium (Cr) | 0.80 – 1.10 |
| Molybdenum (Mo) | 0.15 – 0.25 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.040 |
Chromium improves wear resistance and hardenability, while molybdenum increases strength and helps reduce brittleness during heat treatment.
📊 Mechanical Properties of 4140 Steel
Mechanical properties vary depending on heat treatment condition and section thickness.
| Property | Typical Value |
|---|---|
| Tensile Strength | 850 – 1000 MPa |
| Yield Strength | 650 – 850 MPa |
| Elongation | 12 – 18% |
| Hardness (Annealed) | 197 HB Max |
| Hardness (Pre-Hardened) | 28 – 32 HRC |
| Hardness (Q&T) | 35 – 55 HRC |
4140 steel provides an excellent balance between strength and toughness, making it ideal for heavily loaded components subjected to dynamic stress.
🌍 Why Is the Steel Number 1.7225 Important?
The steel number system helps engineers and international buyers identify equivalent materials across different standards.
For example, the American grade 4140 corresponds closely to the European grade 42CrMo4 with steel number 1.7225.
🌐 International Equivalents of 4140 Steel
| Country/Region | Equivalent Grade |
|---|---|
| Germany | 42CrMo4 / 1.7225 |
| USA | AISI 4140 |
| Japan | SCM440 |
| China | 42CrMo |
| UK | EN19 |
| France | 42CD4 |
Using the correct 4140 steel number is especially important for:
- International procurement
- Material certification
- OEM engineering drawings
- Export manufacturing
- Third-party inspection
Many companies specify material using the steel number because grade names vary between countries.
🔥 Heat Treatment of 4140 Steel
One major advantage of 4140 steel is its excellent heat treatment capability.
🌡️ Typical Heat Treatment Parameters
| Process | Temperature |
|---|---|
| Forging | 850 – 1200°C |
| Annealing | 800 – 850°C |
| Normalizing | 870 – 900°C |
| Hardening | 820 – 860°C |
| Tempering | 540 – 680°C |
After quenching and tempering, the material develops:
- High tensile strength
- Excellent toughness
- Good fatigue resistance
- Improved wear performance
This is why 4140 is commonly selected for quenched and tempered alloy steel applications.
⚙️ Machinability and Weldability
4140 steel offers good machinability in annealed and pre-hardened conditions.
🛠️ Machining Characteristics
| Property | Performance |
|---|---|
| CNC Machining | Very Good |
| Turning Performance | Good |
| Drilling Performance | Good |
| Surface Finish Stability | Excellent |
Pre-hardened 4140 steel is widely used in mold bases, machinery parts, and tooling components because it reduces additional heat treatment costs.
🔩 Weldability
4140 steel can be welded, but proper procedures are necessary due to its alloy content.
Recommended welding practices:
- Preheat before welding
- Controlled interpass temperature
- Post-weld stress relief
- Slow cooling after welding
Improper welding may cause cracking or hardness increase in the heat-affected zone.
🚗 Common Applications of 4140 Steel
4140 steel is widely used across multiple industrial sectors because of its excellent mechanical performance.
🚘 Automotive Industry
- Axles
- Crankshafts
- Connecting rods
- Drive shafts
🏗️ Heavy Machinery
- Hydraulic shafts
- Gear components
- Industrial spindles
- Machine tool parts
🛢️ Oil and Gas Industry
- Drill collars
- Tool joints
- High-pressure connectors
- Structural components
⚡ Tooling and Engineering
- Mold holders
- Forging dies
- Heavy-duty bolts
- Wear-resistant components
Many engineers searching for 4140 steel material specifications prioritize strength, fatigue resistance, and heat treatment stability.
⚖️ 4140 Steel vs 4340 Steel
Although both materials are alloy steels, they differ in alloy composition and toughness.
| Property | 4140 Steel | 4340 Steel |
|---|---|---|
| Chromium Content | Medium | Medium |
| Nickel Content | Low | Higher |
| Toughness | Good | Excellent |
| Strength | High | Very High |
| Cost | Lower | Higher |
4140 steel is often preferred for general industrial applications because it offers strong performance with lower material cost.
🏭 Company Advantages
At Otai Special Steel, we supply high-quality 4140 alloy steel plates, rounds, flats, and forged blocks for global industrial applications.
Our advantages include:
- Large inventory available year-round
- Multiple thicknesses and dimensions in stock
- Customized cutting services
- Heat treatment support
- Ultrasonic testing (UT)
- Chemical composition verification
- Third-party inspection support such as SGS
- Stable export packaging
- Fast international delivery capability
We support customers in automotive manufacturing, heavy machinery, engineering fabrication, tooling production, and oilfield equipment industries worldwide.
❓ FAQ
What is the steel number of 4140 steel?
The European steel number equivalent is 1.7225, corresponding to 42CrMo4 steel.
Is 4140 steel the same as 42CrMo4?
They are considered equivalent grades with very similar chemical composition and mechanical properties.
What is the Japanese equivalent of 4140 steel?
SCM440 is the closest Japanese equivalent grade.
Can 4140 steel be hardened?
Yes. 4140 steel responds very well to quenching and tempering heat treatment.
What hardness can 4140 steel achieve?
Depending on heat treatment, the material can achieve approximately 35–55 HRC.
Is 4140 steel good for shafts and gears?
Yes. Its excellent strength, toughness, and fatigue resistance make it ideal for shafts, gears, and heavily loaded machinery parts.
