GX15CrMo5 Nitriding GX15CrMo5 Alloy Steel Round Bars

Product Description

GX15CrMo5 (Werkstoff / Material Number 1.7365 under EN 10213) is a 5% Chromium–Molybdenum elevated-temperature steel.

In standard European steel nomenclature:

• "G" indicates a cast steel designation.

• "X15CrMo5" denotes ~0.15% Carbon with a nominal 5% Chromium and 0.50% Molybdenum content.

While GX15CrMo5 specifically designates steel castings (such as valve bodies and pump housings), wrought bar products sharing this exact 5% Cr – 0.5% Mo chemical footprint are supplied under X15CrMo5-1 / 1.7390 (EN 10269) or ASTM A182 F5 / A336 F5.

The 5% Chromium content makes this alloy suitable for nitriding, developing a hard, wear- and erosion-resistant surface layer while maintaining structural integrity under elevated temperatures and corrosive environments.

1. Chemical Composition (EN 10213 / EN 10269 Mass %)

2. Mechanical Properties (Quenched & Tempered +QT State)

Round bars are typically supplied in the +QT (Quenched and Tempered) condition prior to machining and surface treatment:

3. Equivalent Standards & Cross-References

4. Nitriding Process Considerations for 5% Cr Steel

High-chromium steels require specific surface handling during nitriding:

1. Surface Depassivation: Steels with $\ge 5\%$ Chromium naturally form a passive chromium oxide ($\text{Cr}_2\text{O}_3$) film. Before gas or plasma nitriding, the surface must be chemically depassivated or sputter-cleaned with ions to allow nitrogen diffusion.

2. Tempering vs. Nitriding Holds: Core quenching and tempering (+QT) must be performed at 650°C – 700°C. Nitriding is subsequently carried out at 510°C – 540°C to prevent core softening during the cycle.

3. Plasma (Ion) Nitriding Advantage: Plasma nitriding is preferred for 5% Cr steels because hydrogen ion bombardment actively strips the oxide layer, ensuring a uniform nitride case without soft spots.

5. Typical Applications

• Refinery & Petrochemical: Hot hydrocarbon valve spindles, pump shafts, trim parts, and erosion-resistant stems.

• Power Generation: High-temperature steam valve rods, boiler feed pump shafts, and turbine fasteners operating up to 550°C.

• Industrial Equipment: High-wear extruding components, abrasive fluid handling equipment, and heavy-duty wear rings.