Nauticalloy 4501 Super Duplex | 1.4501

Nauticalloy 4501 is the top of the super-duplex stainless steel range, engineered for the most demanding marine applications where both exceptional mechanical strength and superior corrosion resistance are absolutely critical.

This super-duplex grade combines the strength advantages of duplex metallurgy with enhanced corrosion resistance, making it a specification choice for extreme marine environments and high-performance propulsion systems.

The optimised super-duplex composition delivers uncompromising performance in aggressive seawater conditions, elevated temperature applications and high-stress marine environments where conventional stainless steel grades cannot meet the demanding operational requirements.

1.4501

Material equivalents

Nauticalloy 4501 super duplex is identified internationally under multiple designation systems, and equals propeller shafts in 1.4501, UNS S32760, Super Duplex F55, SAF 2507®, A182 F55 material grade. This ensures global specification compatibility and supply chain reliability across diverse marine markets.

View Nauticalloy 4501 data sheet

Chemical Composition

Element	C	Si	Mn	P	S	Cr	Ni	Mo	N
% min	-	-	-	-	-	24.00	6.00	3.00	0.20
% max	0.03	1.00	1.00	0.035	0.015	26.00	8.00	4.00	0.30

Chemical composition (% by weight)

Mechanical properties

Property	Rp0.2 (Proof Strength)	UTS (Tensile Strength)	Elongation A4 %	Reduction of Area %	Hardness BHN (max)
Metric (MPa / N/mm²)	>550 MPa	>750 MPa	25	25	<270
Imperial (ksi)	>80 ksi	>110 ksi	25	25	<270

Characteristics

Enhanced dual-phase microstructure

Nauticalloy 4501 exhibits a balanced dual-phase microstructure of approximately equal proportions of austenite and ferrite phases, optimised with enhanced alloy content to deliver exceptional performance. The super-duplex composition provides significantly superior properties compared to standard duplex grades through increased chromium, molybdenum and nitrogen content.

Exceptional pitting resistance

The enhanced alloy composition delivers a Pitting Resistance Equivalent Number (PREN) exceeding 40, providing outstanding resistance to pitting and crevice corrosion in aggressive marine environments including heated seawater and high-chloride conditions.

Superior strength-to-weight

Mechanical strength with tensile strength capabilities up to 1,000 MPa, enabling lightweight, cost-efficient marine component designs whilst maintaining structural integrity under extreme loading.

Critical pitting temperature performance

Critical Pitting Temperature exceeding 50°C in seawater environments, demonstrating superior performance in elevated temperature marine applications and tropical operating conditions.

Marine applications and benefits

Nauticalloy 4501 is the premium choice for marine propeller shaft systems operating in the most challenging conditions, including high-temperature seawater, aggressive marine atmospheres and extreme mechanical loading scenarios where conventional grades cannot provide adequate service life.

The exceptional corrosion resistance and high strength make this grade ideal for oil and gas, marine and chemical processing applications where reliability is paramount and component failure consequences are severe.

Applications extend to critical marine equipment including high-pressure pump shafts, valve components, offshore platform equipment and subsea instrumentation where the combination of strength and corrosion resistance provides unmatched operational reliability.

Outstanding resistance to pitting and crevice corrosion in seawater and chloride-containing environments, with excellent resistance to stress corrosion cracking in sour and chloride conditions, making it suitable for the most aggressive applications.

Processing Quality Assurance Nauticalloy 4462 Nauticalloy 4542 Nauticalloy 4404

For Nauticalloy 4501 technical consultation, contact our specialist technical sales team at +44 (0)1902 409409 or email sales@millstockstainless.com

Nauticalloy 4501