What is the PREN value of 1.4565 super austenitic steel?

Mar 18, 2026

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1.4565 stainless steel, commonly known as Alloy 24 or UNS S34565, is a high-strength, nitrogen-strengthened austenitic stainless steel that offers an exceptional combination of high strength, excellent corrosion resistance, and good wear and galling resistance. With its high nitrogen content and balanced alloying elements, it achieves approximately twice the yield strength of conventional austenitic grades like 316L while maintaining excellent ductility and toughness. This makes it suitable for demanding applications in aerospace, marine, chemical processing, and high-stress fastener industries where both strength and corrosion resistance are critical.

Standard	Equivalent Grade
EN (Europe)	1.4565
ASTM/AISI (USA)	Alloy 24, UNS S34565
Common Name	Nitronic 50, Alloy 24

Element	C	Si	Mn	P	S	Cr	Ni	Mo	N
Content (%)	≤ 0.03	≤ 1.0	5.0 - 7.0	≤ 0.03	≤ 0.015	16.0 - 18.0	11.0 - 14.0	2.0 - 3.0	0.20 - 0.40

Property	Yield Strength (Rp0.2)	Tensile Strength (Rm)	Elongation (A)	Hardness (HB)
Typical Value	≥ 415 MPa	760 - 965 MPa	≥ 35%	≤ 270

High Strength and Good Toughness: Provides approximately twice the yield strength of 316 stainless steel while maintaining excellent impact toughness, even at cryogenic temperatures.

Excellent Corrosion Resistance: Offers corrosion resistance superior to 316L in many environments, with better resistance to chloride pitting and crevice corrosion (PREN typically 32-35).

Good Wear and Galling Resistance: Performs well in moving contact applications, such as bearings, bushings, and valve components, due to its high work hardening rate.

Non-Magnetic: Remains essentially non-magnetic even after severe cold working, making it suitable for instrumentation and medical applications.

Aerospace: Fasteners, landing gear components, and high-stress structural parts.

Marine: Shafts, pumps, valves, and fittings in seawater environments.

Chemical Processing: High-stress components exposed to corrosive media.

Oil & Gas: Downhole tools, wellhead components, and high-pressure fasteners.

Medical: Surgical instruments and implants.

Pulp & Paper: Doctor blades, cutter bars, and wear components.

Alloy 24 is an austenitic stainless steel strengthened by nitrogen, while 17-4PH is a martensitic precipitation-hardening grade. Alloy 24 offers better corrosion resistance, especially in chloride environments, and maintains its properties at cryogenic temperatures. It remains non-magnetic, while 17-4PH is magnetic. 17-4PH can achieve higher hardness and strength through aging (up to 44 HRC vs. 28 HRC for Alloy 24) but may be more susceptible to stress corrosion cracking. Alloy 24 has better weldability without post-weld heat treatment and superior toughness. The choice depends on application requirements: Alloy 24 for corrosion resistance and toughness, 17-4PH for maximum strength and hardness.

Alloy 24 has a high work hardening rate, which can make machining more challenging than standard austenitic grades. Recommended practices include using rigid setups, sharp cutting tools, moderate speeds and feeds, and adequate cooling. It is often machined in the annealed condition. Despite its high strength, it can be machined successfully with proper techniques. For tapping and threading, specially designed tools may be required due to its tendency to work harden. The material responds well to grinding and polishing, achieving excellent surface finishes.

Alloy 24 is suitable for a wide temperature range from cryogenic conditions up to about 350°C (662°F) for continuous service. Its high nitrogen content provides excellent strength retention at elevated temperatures, while its austenitic structure ensures outstanding toughness at cryogenic temperatures down to -196°C. For applications requiring higher temperature capability, other grades may be more suitable. The alloy maintains good corrosion resistance up to about 300°C, above which long-term exposure may affect properties.

GNEE Steel supplies high-performance Alloy 24 (1.4565/UNS S34565) stainless steel in bar, wire, plate, and forging forms for demanding aerospace, marine, and industrial applications. We provide full material certification (EN 10204 3.1) and processing support. If you have any requirements, please feel free to contact us.