Material Knowledge – 38MnVS6

38MnVS6 is a micro-alloyed, medium-carbon steel developed for applications requiring high mechanical properties and a smooth surface.

In the material's composition, manganese (Mn) and vanadium (V) play a particularly important role: manganese increases the steel's strength and hardenability, while vanadium has a grain-refining and precipitation-hardening effect, which significantly improves the material's strength and wear resistance.

In the case of chrome-plated round bars, surface hardness and corrosion resistance can be further increased by surface hardening and hard chrome plating.

Standards and Designations:

• EN 10267:1998 (38MnVS6): European standard for steels, which regulates ferrite-pearlite steels produced by precipitation hardening from the hot-working temperature.

• 1.1303: Material number.

• Similar designations: 39MnV5, 1.1303.

Chemical Composition (typical values according to EN 10267:1998, %):

During production, 38MnVS6 steel typically gains its mechanical properties as a result of controlled cooling after hot working (e.g., normalization, or precipitation hardening), and does not necessarily undergo conventional quenching and tempering. This steel is often supplied in the so-called "+P" (precipitation hardened) or "+QT" (quenched and tempered) condition, which denotes the final mechanical properties.

• Non-hardened (e.g., +AR or +N condition): In this condition, the steel is in the "as-rolled" or normalized state. At this point, the strength parameters are lower, but the material is still easily machinable. 38MnVS6 is fundamentally a so-called micro-alloyed steel, which exhibits relatively high strength even in the normal rolled or normalized state due to the refining and precipitation-hardening effect of vanadium.

• Mechanical properties (in +AR/N condition): Tensile strength (Rm) is typically around 600-750 MPa, and yield strength (Rp0.2) is around 400-500 MPa. Hardness is generally 200-240 HB.

• Hardened (surface hardened, e.g., induction hardened) or Quenched and Tempered (+QT, +P condition): For hydraulic piston rods, 38MnVS6 steel is often subjected to induction hardening. This surface heat treatment creates an extremely hard layer on the rod's surface, while the core remains tough and flexible. Hardening increases surface wear resistance, bending strength, and fatigue resistance, which is critical in dynamically loaded hydraulic systems. This is followed by hard chrome plating, which provides additional wear and corrosion resistance.

• Mechanical properties (in +QT / Induction hardened condition):

• Tensile strength (Rm): Significantly higher, can reach 800-1000 MPa.

• Yield strength (Rp0.2): Higher, typically above 520 MPa.

• Surface hardness (after induction hardening, under the chrome layer): Minimum 55 HRC (approximately 600 HV), while the chrome layer itself can have a hardness of over 850 HV0.1.

• Hardening depth: Depending on the diameter, it can be 1-2.5 mm, which ensures adequate load-bearing capacity.

Comparison:

In hydraulic and pneumatic systems, the hardened and chrome-plated version is used almost exclusively, as surface hardness, wear resistance, and fatigue resistance are critical for the long lifespan of piston rods and other moving parts.

Chrome-plated round bars, such as the hardened and chrome-plated version of 38MnVS6, are essential in the manufacture of hydraulic and pneumatic cylinders and other moving parts. The surface treatment, i.e., hard chrome plating, plays a decisive role in performance and lifespan.

• Hard chrome layer: Usually a minimum of 20 µm thick, this extremely hard (min. 800 HV) and corrosion-resistant layer protects the underlying steel material from wear, scratches, and environmental influences. This layer is vital for the life of seals in hydraulic systems, as it minimizes friction and wear.

• Surface roughness (Ra): Very low, typically less than 0.2 µm, which contributes to the long-term tightness of seals and the optimal functioning of hydraulic oil.

Main application areas in hydraulics and pneumatics:

• Piston rods for hydraulic cylinders: This is the most common application, where hardened and chrome-plated 38MnVS6 performs excellently under high-pressure, dynamic loads, and the need for wear resistance.

• Rods for pneumatic cylinders: Similar to hydraulics, wear resistance and a smooth surface are also essential here.

• Guide rods and shafts: In machines and equipment where precise movement and high loads are required.

• Agricultural machinery, construction machinery, mining equipment: In these areas, a robust and durable material is essential due to harsh environmental conditions and high stress.

Steel, as a material, is outstandingly sustainable thanks to its full recyclability.

Chrome-plated round bars based on 38MnVS6 contribute to the reliability and economical operation of hydraulic systems with their long lifespan, low maintenance requirements, and excellent performance.

The hardened and chrome-plated surface extends the life of the components, reducing the frequency of replacements and waste.