What is uns S41500 material?

What is UNS S41500 Material?

Published: November 7, 2025 | Updated: November 7, 2025By Gangsteel Engineering Team – 25+ Years in Stainless Steel Export Excellence

In the vast landscape of stainless steels, UNS S41500 emerges as a standout martensitic grade, offering a compelling mix of high strength, good toughness, and moderate corrosion resistance that makes it a favorite for challenging industrial applications. As a leading producer and exporter based in China, Gangsteel has manufactured and supplied thousands of tons of UNS S41500 material in forms like plates, bars, and forgings to clients worldwide in oil & gas, petrochemical, marine, and power sectors. If you've encountered this grade in specs like ASTM A240 or A182 and wondered about its core characteristics, composition, properties, and uses, this comprehensive overview is designed to clarify everything. We'll explore what UNS S41500 is, why it's valued, and how it performs in real-world scenarios, drawing from our extensive production experience and mill data.

Consider a recent example from our portfolio: In 2024, a major Gulf refinery upgraded its sour gas processing equipment with UNS S41500 forgings from Gangsteel. The material's balanced properties allowed it to withstand H2S exposure at 150°C without pitting or cracking, extending component life by 30% compared to previous 410 SS parts, as confirmed by their corrosion monitoring reports. Also known as F6NM (Forged 6% Nickel Martensitic) or AISI 415, UNS S41500 isn't a superalloy for extreme conditions, but its cost-effectiveness and versatility make it ideal for environments where strength meets moderate corrosives. With a density of 7.85 g/cm³, it's weight-efficient for large structures, and its heat-treatable nature allows customization from soft machining states to hardened service conditions. Let's break it down step by step, from its definition to practical applications, so you can see why this material might be the right fit for your project.

Defining UNS S41500: The Fundamentals

UNS S41500 is a Unified Numbering System designation for a low-carbon martensitic stainless steel, part of the 400-series family but enhanced with nickel and molybdenum for superior performance over basic grades like 410. "Martensitic" refers to its microstructure, formed through rapid cooling (quenching) that creates a hard, needle-like crystal structure, giving it high strength and hardness. However, unlike fully hard martensitics that can be brittle, S41500's additions make it "soft martensitic," allowing tempering for balanced toughness.

Developed for applications requiring weldability and impact resistance in mildly corrosive settings, UNS S41500 is spec'd in standards like ASTM A240 (plates and sheets), A182 (forged fittings), A473 (forgings), and A479 (bars). It's magnetic, heat-treatable, and offers a PREN (Pitting Resistance Equivalent Number) of 18-22, providing better pitting resistance than carbon steels but not as high as austenitic grades like 316. Density at 7.85 g/cm³ (or 0.284 lb/in³) is typical for martensitic SS, derived from its iron-heavy base, making it denser than aluminum but lighter than nickel alloys for efficient designs.

What makes it special? The low carbon (0.05% max) prevents carbide sensitization during welding, while nickel (3.5-5.5%) tempers the martensite for ductility, and molybdenum (0.5-1.0%) boosts chloride resistance. This results in a Carbon Equivalent under 0.40, easing fabrication. At Gangsteel, we melt S41500 using advanced processes like AOD for ultra-low impurities, often achieving P and S below 0.015% for enhanced properties.

Chemical Composition: The Building Blocks

The chemical makeup of UNS S41500 is precisely controlled to deliver its signature properties, with low carbon for weldability and alloying for resistance and strength. Below is the standard composition (heat analysis, % by weight):

This composition ensures a low risk of intergranular corrosion and good performance in sour service (NACE MR0175 compliant when hardness is controlled). Gangsteel's production often features tighter tolerances, like P and S <0.015%, for superior weldability and fatigue life.

Mechanical Properties: Strength and Toughness

UNS S41500's mechanical properties are highly tunable through heat treatment, making it adaptable for various uses. In the quenched and tempered condition (standard for most applications), it offers:

Heat treatment: Anneal at 1010-1120°C, quench, temper at 565-760°C (2 hours) to adjust properties—lower temps for higher strength, higher for ductility. Density remains 7.85 g/cm³ across treatments, aiding consistent weight calculations.

Physical Properties: Supporting Practical Use

Physical traits of UNS S41500 complement its mechanicals:

These make it suitable for environments from -196°C (cryogenic) to 425°C (elevated), with density key for buoyancy in marine designs.

Corrosion Resistance and Weldability

S41500 provides moderate corrosion resistance, with Cr forming a passive film effective against rust, mild acids, and CO2. Mo boosts pitting in chlorides (corrosion rate <0.1 mm/year in neutral solutions), and it's NACE MR0175-compliant for H2S sour service when hardness <22 HRC. Not for strong acids or high salinity without coatings.

Weldability is excellent: Use E410NiMo filler, 150-200°C preheat for thick sections, PWHT at 620°C to restore properties. Machinability: Fair in annealed state (60-70% of carbon steel).

Applications: Where UNS S41500 Shines

UNS S41500 is used in:

• Oil & Gas: Valves, wellheads (sour service resistance).
• Petrochemical: Pressure vessels, reactors (thermal stability).
• Marine: Shafts, risers (pitting resistance).
• Power Generation: Turbine parts (high strength).
• Mining: Wear components (toughness).

Gangsteel has supplied for Saudi sour wells, where it lasted 5 years without corrosion issues.

Equivalents: Global Alternatives

Common equivalents:

• EN/DIN: 1.4313 (X3CrNiMo13-4) – Nearly identical for European use.
• AISI/SAE: 415 – Legacy U.S. name.
• AFNOR: Z6CND13-04 – French standard.
• JIS: SUSF415 – Japanese forging equivalent.
• BS: 416S21 – British variant.

These share properties for substitution.

Sourcing UNS S41500 from Gangsteel

Gangsteel offers UNS S41500 at $2,600-2,800 USD per ton FOB, with stock in 1-200mm thicknesses. MOQ: 1 ton; lead time: 7-30 days. Certs: EN 10204 3.1/3.2, third-party inspections. Custom equivalents available.

Explore our astm a240 /a240m or asme sa240/sa240m for related products.

FAQ: UNS S41500 Material Questions Answered

Q: What is UNS S41500 material, and what type of stainless steel is it?

A: UNS S41500 is a low-carbon martensitic stainless steel, known for its high strength (795 MPa tensile min), good toughness (27 J impact at -18°C), and moderate corrosion resistance (PREN 18-22). It's heat-treatable, magnetic, and offers better weldability than harder martensitics like 410 due to low carbon (0.05% max) and additions like nickel (3.5-5.5%) and molybdenum (0.5-1%). Often called F6NM or AISI 415, it's used in forged or wrought forms for parts needing durability in mildly corrosive environments. Gangsteel produces it to specs like ASTM A240, where its density of 7.85 g/cm³ supports efficient designs.

Q: What are the main properties of UNS S41500 material?

A: UNS S41500 has tensile strength of 795 MPa min, yield strength of 620 MPa min, elongation of 15% min, hardness of 32 HRB max, and impact toughness of 27 J at -18°C. Physical properties include density 7.85 g/cm³, thermal conductivity 25 W/m·K, and expansion 10.5 × 10^-6 /°C. Corrosion resistance is moderate, with good performance in H2S (NACE-compliant) and mild acids, but not for strong corrosives. It's weldable and machinable annealed. Gangsteel's material often exceeds minima, with tensile up to 950 MPa in tempered state.

Q: What is the chemical composition of UNS S41500?

A: The composition is C 0.05 max, Mn 0.50-1.00, Si 0.60 max, P 0.030 max, S 0.030 max, Cr 11.50-14.00, Mo 0.50-1.00, Ni 3.50-5.50, N 0.10 max, Fe balance. This low-carbon setup prevents sensitization, while Cr provides passivation, Mo boosts pitting resistance, and Ni improves toughness. The formula yields a low Carbon Equivalent (<0.40) for weldability. Gangsteel's melts feature low impurities for enhanced corrosion and fatigue properties.

Q: What are common applications for UNS S41500 material?

A: UNS S41500 is used in oil & gas valves and wellheads (sour service), petrochemical pressure vessels, marine shafts and risers (pitting resistance), power generation turbine parts (high strength), and mining wear components (toughness). Its properties suit environments with moderate corrosives and high stress. Gangsteel has supplied for Saudi sour wells, where it endured H2S without failure for 5 years, and Brazilian reactors with 30% reduced erosion.

Q: How is UNS S41500 material heat treated?

A: Heat treatment involves annealing at 1010-1120°C (air cool) for softness, quenching from the same range for martensite, and tempering at 565-760°C (2 hours) to balance properties—lower temps for strength (795 MPa+), higher for ductility (15%+ elongation). For NACE, temper to hardness <22 HRC. This doesn't affect density (7.85 g/cm³). Gangsteel's controlled processes ensure uniform results, with treatment optimizing for applications like cryogenic use.

Q: What is the corrosion resistance of UNS S41500?

A: UNS S41500 offers moderate corrosion resistance, with Cr forming a passive film effective against rust, mild acids, and CO2 (<0.1 mm/year rate). Mo enhances pitting in chlorides, and it's NACE MR0175-compliant for H2S sour service up to 10% at 150°C when hardness controlled. Not suited for strong acids or high salinity without coatings. Gangsteel's low-impurity material shows 20-30% better performance in field tests.

Q: What are equivalents to UNS S41500 material?

A: Common equivalents include EN 1.4313 (X3CrNiMo13-4) for Europe, AISI 415 for U.S. legacy, AFNOR Z6CND13-04 for France, JIS SUSF415 for Japan, and BS 416S21 for UK. These share chemistry and properties for substitution, e.g., 1.4313 for CE-marked parts. Gangsteel offers dual-cert material for seamless use.

Q: Where can I buy UNS S41500 material?

A: Gangsteel supplies UNS S41500 at $2,600-2,800 USD per ton FOB, with stock in 1-200mm thicknesses. Forms include plates, bars, and forgings; MOQ 1 ton, lead time 7-30 days. Certs: EN 10204 3.1/3.2, third-party inspections. Contact us for quotes—global delivery available.