AISI 431/ 1.4057/ X17crni16-2 equivalent material
Oct 28, 2026
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If you are looking for AISI 431, EN 1.4057, or X17CrNi16-2 stainless steel round bars for pump shafts, valve components, marine hardware, or other mechanically stressed parts, understanding their international equivalents can help you source the correct material and avoid specification mismatches.
What Is AISI 431 / 1.4057 / X17CrNi16-2 Stainless Steel?
AISI 431 is a chromium-nickel martensitic stainless steel that can be hardened and tempered to achieve high mechanical strength. Its European designation is EN 1.4057, and its EN grade name is X17CrNi16-2. The material is commonly selected for components that need a combination of strength, hardness, and better corrosion resistance than many conventional 12–13% chromium martensitic grades.
Chemical Composition of 1.4057 / AISI 431
The chemical composition determines hardenability, corrosion resistance, and mechanical response after heat treatment. The following limits are based on the referenced EN 10088-3 composition for 1.4057.
| Element | Chemical Composition (wt. %) |
|---|---|
| Carbon (C) | 0.12–0.22 |
| Chromium (Cr) | 15.0–17.0 |
| Nickel (Ni) | 1.50–2.50 |
| Silicon (Si) | ≤1.00 |
| Manganese (Mn) | ≤1.50 |
| Phosphorus (P) | ≤0.040 |
| Sulfur (S) | ≤0.030 |
| Iron (Fe) | Balance |
Mechanical Properties of AISI 431 QT800 and QT900 Conditions
AISI 431 / 1.4057 can be supplied in different delivery conditions. For quenched-and-tempered round bars, QT800 and QT900 identify different mechanical property levels in the referenced EN 10088-3 data.
| Mechanical Property | QT800 | QT900 |
|---|---|---|
| Tensile strength, Rm | 800–950 MPa | 900–1,050 MPa |
| Minimum 0.2% proof strength, Rp0.2 | 600 MPa | 700 MPa |
| Minimum elongation, A5, diameter ≤60 mm | 14% | 12% |
| Minimum elongation, A5, diameter >60–160 mm | 12% | 10% |
| Minimum longitudinal Charpy impact energy, diameter ≤60 mm | 25 J | 16 J |
| Minimum longitudinal Charpy impact energy, diameter >60–160 mm | 20 J | 15 J |
AISI 431 / 1.4057 Stainless Steel:Corrosion Resistance
AISI 431 / 1.4057 contains 15.0–17.0% Cr and 1.5–2.5% Ni, outperforming AISI 420 and 410. It withstands fresh water, atmospheric exposure and weak organic acids. It is vulnerable to pitting and crevice corrosion in high-chloride or strong acid environments. Its corrosion performance is inferior to austenitic grades like 316L, fitting only mild corrosion service conditions.
AISI 431 / 1.4057 Stainless Steel:Heat Treatment Performance
1.4057 is hardenable by quenching and tempering. Austenitize at 950–1050°C, followed by oil or forced air quenching. Adjust tempering temperature to target QT800 or QT900. Tempering between 420–520°C must be avoided to prevent 475°C embrittlement. Proper heat treatment stabilizes its microstructure and delivers consistent mechanical properties.
AISI 431 / 1.4057 Stainless Steel:Machinability
AISI 431 QT800 / QT900 has fair machinability at 240–320 HB. Its martensitic matrix causes higher tool wear than austenitic stainless steel such as 304. Stable cutting speed, sharp tooling and adequate coolant are required for turning, milling and grinding. Annealed stock is easier to machine, while QT finished bars need optimized cutting parameters to reduce chattering.
AISI 431 / 1.4057 Stainless Steel:Weldability
AISI 431 (1.4057) has limited weldability. The heat-affected zone readily forms hard brittle martensite and cracks. Preheat to 200–300°C and post-weld tempering at 600–680°C are mandatory. Matching martensitic filler wire is required. Weld joints cannot retain original QT strength, so it is not recommended for critical load-bearing welded assemblies.
If you have project requirements for AISI 431 / 1.4057 / X17CrNi16-2 stainless steel, we welcome your orders. GNEE maintains a large inventory of popular products for you to choose from. We offer a variety of practical product forms, including plates, coils, pipes, bars, and wire. Please contact our facility today for detailed chemical composition specifications or to request free samples. We provide competitive pricing and excellent service.
AISI 431 / 1.4057 Stainless Steel price per kg
The price of AISI 431 / EN 1.4057 (X17CrNi16-2) stainless steel typically ranges from $2.20 to $4.50 per kilogram (for reference only), depending on the product form, order quantity, surface finish, and heat treatment condition. For instance, round bars in the QT800 or other quenched-and-tempered conditions may be priced higher than standard hot-rolled material.
FAQ
What is the difference between AISI 431 and AISI 410 or 420?
AISI 410, 420 and 431 are martensitic stainless steels. AISI 410 has ≤0.15% C with basic strength; AISI 420 raises carbon to 0.15–0.40% for higher hardness. AISI 431 adds 1.5–2.5% Ni alongside 15–17% Cr, delivering superior toughness and better corrosion resistance. It can reach QT800/QT900 strength grades, making it preferred for pump shafts instead of general cutting blades.
Can AISI 431 stainless steel be hardened by heat treatment?
Yes, AISI 431 (1.4057, X17CrNi16-2) is fully hardenable via quenching and tempering. Austenitize at 950–1050°C, then oil or air quench. Tuning tempering temperature yields QT800 (Rm 800–950 MPa) or QT900 (Rm 900–1050 MPa). Avoid 420–520°C tempering range to prevent 475°C embrittlement and maintain balanced toughness.
What is the difference between AISI 431 and SUS431?
Essentially, AISI 431 and SUS431 denote the same martensitic stainless grade, X17CrNi16-2 / 14Cr17Ni2. AISI 431 follows the US ASTM standard, while SUS431 is the Japanese JIS designation. Their core chemical limits (15.0–17.0% Cr, 1.5–2.5% Ni) are closely aligned. Minor permissible tolerance differences exist, and both are supplied in QT800 or QT900 quenched-tempered condition.
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