1.7365 Nitriding Steel Bar 1.7365 Alloy Steel Round Bars

Product Description

1.7365 is a Werkstoff/EN material designation for nitriding alloy steel round bars, typically supplied in the quenched and tempered condition (+QT) ready for machining and surface hardening.

Depending on the governing standard or specification, 1.7365 corresponds to two distinct European/British material footprints:

1. 3% Cr-Mo Aerospace & High-Strength Wrought Bar (BS 4S106 / BS S106 / EN40B / 32CrMo12 equivalent): Used for aerospace turbine shafts, racing crankshafts, and heavy-duty gears.

2. 5% Cr-Mo Heat-Resistant Cast/Wrought Steel (GX15CrMo5 per EN 10213): Used primarily in elevated-temperature pump shafts, steam valves, and petrochemical processing.

1. Chemical Composition Comparison

2. Mechanical Properties (Supply Condition vs. Nitrided)

Round bars are typically supplied in the pre-heat-treated +QT (Quenched & Tempered) condition, enabling parts to be machined to final shape and surface-hardened with minimal dimensional movement.

3. Global Equivalents & Specifications

4. Nitriding & Processing Steps

To achieve maximum surface hardness without core softening or warping:

1. Supply State: Procure bars as 1.7365 +QT (bright peeled, turned, or precision ground).

2. Rough Machining: Machine leaving $0.5\text{--}1.0\text{ mm}$ for final finishing stock.

3. Stress Relieving: Heat to 550°C – 580°C for 2+ hours and slow cool (temperature must be at least 30°C higher than the planned nitriding hold).

4. Finish Machining: Finish grind/turn to final pre-nitride dimensions.

5. Nitriding: Perform gas or plasma (ion) nitriding at 500°C – 530°C for 20 to 80 hours depending on required effective case depth.

5. Typical Engineering Applications

• Aerospace & Defense: Main gas turbine drive shafts, actuator power screws, turbine fasteners, high-duty fuel pump shafts, and gear pinions.

• Motorsport & Automotive: Racing engine crankshafts, camshafts, output shafts, wrist pins, and transmission gears.

• Industrial Equipment: Injection molding feed screws, extruding barrels, high-pressure pump spindles, and valve rods.