- Grade / Alloy
- 1.4123
- EN / W.Nr.
- 1.4123X40CrMoVN16-2
- AISI / SAE
- —
- UNS
- S42025
- Family
- Martensitic
Chemical composition
Chemical composition
Composition limitsComposition limits for long products within EN 10088-3.
| Element | Content (% by mass) |
|---|---|
| CCarbon | 0.35–0.5 |
| SiSilicon | ≤ 1 |
| MnManganese | ≤ 1 |
| PPhosphorus | ≤ 0.04 |
| SSulfur | ≤ 0.015 |
| CrChromium | 14–16 |
| MoMolybdenum | 1–2.5 |
| NiNickel | ≤ 0.5 |
| VVanadium | ≤ 1.5 |
| NNitrogen | 0.1–0.3 |
Values describe the grade, not the analysis of a specific batch. The applicable product specification and material certificate determine acceptance. A dash does not mean zero.
Key properties of 1.4123
1.4123 is a martensitic stainless steel containing chromium, molybdenum, vanadium and nitrogen. It is identified as X40CrMoVN16-2 and UNS S42025. It is used in small, precise components where hardness and wear resistance matter alongside protection against corrosion. This combination distinguishes it from a steel valued only for hardness: the behaviour of contacting surfaces is also an important part of its applications.
Use in bearings and injection components
Ball and roller bearings and fuel-injection systems are recognised applications. In these components, relatively small surfaces carry forces while acting as part of a precise mechanism. The wear and corrosion characteristics of 1.4123 are associated with that combination. Surgical instruments are another application where surface quality and mechanical properties both matter.
Why nitrogen matters
Nitrogen forms part of the alloy design of this grade. Alongside molybdenum and vanadium, it contributes to the balance sought in a material for hardness and corrosion behaviour. Not every nitrogen-bearing stainless steel belongs to the same family, however. Grade 316LN is an austenitic process material, whereas 1.4123 is a hardenable martensitic grade. The presence of the same element in different steels does not make their applications or properties identical.
Its relationship to 440C and other hard stainless steels
Both 440C and 1.4123 can appear in applications involving hardness and wear resistance. Their carbon levels and alloy balances differ, however; one is not another name for the other. The nitrogen, molybdenum and vanadium combination of 1.4123 makes it a distinct option for precision contact components. The composition identifying the grade is also separate from the characteristics of a particular producer’s specialised remelted product.
Typical application areas
Bearings, injection systems and precision components.
Product and cutting options
Relevant product forms for this material are listed below. Availability varies with grade and dimensions.