Nauticalloy 4057 AISI 431 | 1.4057

Nauticalloy 4057 is a highly cost-effective engineering solution when exceptional mechanical strength is the primary requirement and moderate corrosion resistance is acceptable for the operational environment.

This hardenable martensitic stainless steel delivers superior tensile strength and torsional properties, making it suited to marine shaft applications where strength performance takes precedence. The optimised martensitic composition provides a balance of high strength, reasonable corrosion resistance and economic value, establishing it as a cost-efficient choice for marine applications requiring mechanical performance without the premium of higher-alloy corrosion-resistant grades.

1.4057

Material equivalents

Nauticalloy 4057 has other designations such as: 1.4057, AISI 431, UNS S43100, SUS 431, 431S29, ensuring that a propeller shaft in Nauticalloy 4057 is fully compatible to replace i.e. an existing propeller shaft in AISI 431. This grants global specification compatibility and supply chain reliability across diverse marine markets.

View Nauticalloy 4057 data sheet

Chemical Composition

Element	C	Si	Mn	P	S	Cr	Ni	Mo	N
% min	0.12	-	-	-	-	15	1.50	-	-
% max	0.22	1.00	1.50	0.04	0.03	17.00	2.50	-	-

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)	>600 MPa	800 - 950 MPa	14	12	<290
Imperial (ksi)	>87 ksi	115 - 140 ksi	14	12	<290

Characteristics

Hardenable martensitic structure

Nauticalloy 4057 uses a chromium-nickel martensitic microstructure that can be hardened through controlled heat treatment processes to achieve exceptional strength characteristics. The martensitic matrix provides superior mechanical properties compared to austenitic grades whilst maintaining reasonable corrosion resistance for moderate marine environments.

Temperature performance range

The material maintains excellent mechanical properties across operational temperature ranges from -40°C to 400°C, providing reliable performance in diverse environmental conditions whilst retaining dimensional stability and strength.

High chromium content benefits

The 15-17% chromium content provides good general corrosion resistance and excellent resistance to oxidising environments including nitric acid conditions. This chromium level ensures adequate marine atmosphere resistance whilst enabling the strength characteristics of martensitic metallurgy.

Nickel addition advantages

The 1.5-2.5% nickel addition enhances toughness and ductility characteristics compared to straight chromium martensitic grades, providing improved impact resistance and fabrication properties essential for component applications.

Marine applications and benefits

Nauticalloy 4057 finds primary application in marine propeller shaft systems where exceptional strength and torsional properties are essential whilst moderate corrosion resistance is acceptable. The mechanical characteristics enable optimised shaft designs with reduced diameter specifications.

The combination of high tensile strength, good toughness and reasonable corrosion resistance makes this grade suitable for marine engineering applications including thrust washers, couplings and mechanical drive components subjected to high loading.

Applications extend to pump shafts, valve components and mechanical equipment where the strength advantages of martensitic metallurgy provide enhanced performance compared to austenitic grades in controlled environments.

The material demonstrates adequate performance in mild marine environments where direct seawater contact is limited, making it suitable for above-waterline marine applications and marine equipment operating in controlled atmospheric conditions.

Processing Quality Assurance Nauticalloy 4462 Nauticalloy 4542 Nauticalloy 4404 Nauticalloy 4501

For Nauticalloy 4057 technical consultation, contact our specialist technical sales team at +44 (0)1902 409409 or email sales@millstockstainless.com

Nauticalloy 4057