31CrMoV9 / 1.8519 – High-alloy nitriding steel for extremely demanding components
31CrMoV9 (1.8519, ČSN 15 330) is a high-alloy nitriding steel with excellent hardenability, high strength and the ability to achieve an extremely hard surface layer after nitriding. It is mainly used where long service life, fatigue resistance, wear resistance and stability at elevated temperatures are required.
Properties of 31CrMoV9 (1.8519)
🔩 High strength and toughness
This engineering steel offers very good tensile strength and yield strength, making it suitable for dynamically and thermally loaded components.
⚙️ High hardness after nitriding
After nitriding, a surface hardness of approximately 700–900 HV can be achieved depending on the treatment process, making it ideal for parts exposed to severe wear.
🔥 Heat resistance
The material maintains its mechanical properties even under prolonged exposure to elevated temperatures.
🛡️ Improved corrosion resistance
The presence of chromium, molybdenum and vanadium increases resistance to corrosion and aggressive environments.
📏 Dimensional stability during heat treatment
This steel is suitable for precision-engineered machine parts where dimensional accuracy is important.
Chemical composition of 31CrMoV9 (1.8519)
| Element | Content (%) |
|---|---|
| C | 0.28 – 0.33 |
| Cr | 2.20 – 2.50 |
| Mo | 0.15 – 0.25 |
| V | 0.22 – 0.30 |
| Mn | 0.60 – 0.90 |
| Si | 0.10 – 0.40 |
| P | ≤ 0.025 |
| S | ≤ 0.035 |
Typical applications of 31CrMoV9
🚗 Automotive industry
- crankshafts
- camshafts
- transmission shafts
- gears
- piston pins
✈️ Aerospace industry
- highly stressed shafts
- gears
- structural and load-bearing components
⚡ Energy industry
- turbine components
- rotors
- spindles
- bearing housings
🏭 Mechanical engineering
- pressing components
- milled and turned precision parts
- parts exposed to wear and vibration
Heat treatment (guideline values)
- Quenching and tempering: 850–880 °C, quenching in oil or water
- Tempering: 540–680 °C depending on the required strength
- Nitriding: 480–530 °C, surface hardness up to 700–900 HV
Comparison with equivalent grade – 30CrMoV9 (1.7707, ČSN 15 241)
Steel 31CrMoV9 (1.8519) is very close in composition and properties to 30CrMoV9 (1.7707), and in many applications the two grades can be used interchangeably.
Common properties
- high strength
- excellent hardenability
- extremely high hardness after nitriding (up to approx. 800 HV)
- good heat resistance
Differences
- 31CrMoV9 has a higher content of Cr and V, which increases hardness and wear resistance
- 30CrMoV9 is usually a more economical alternative while still offering very good quality
- 1.8519 provides slightly better stability under long-term thermal loading
Why choose 31CrMoV9 / 1.8519?
31CrMoV9 is an excellent choice for demanding technical applications where high core strength, very hard nitrided surfaces, wear resistance and thermal stability are required. It is particularly suitable for high-performance shafts, gears and precision components working under heavy mechanical and thermal stress.
