AISI 431 / 1.4057 Stainless Steel

Stainless Steel AISI 431 / EN 1.4057: Properties, Applications, and Features

✅ General Technical Characteristics

Stainless steel AISI 431 (EN 1.4057) is a high-quality martensitic stainless steel with increased chromium content, providing high mechanical strength, hardness, and corrosion resistance. It responds well to heat treatment, allowing for enhanced performance characteristics.

Main Characteristics:

• High strength and hardness after quenching.
• Corrosion resistance in fresh water, mild acids, and atmospheric conditions.
• Good wear resistance and ability to withstand mechanical loads.
• Hardening capability for improved strength.
• Limited weldability due to high hardness.

🔬 Chemical Composition AISI 431 / EN 1.4057 (%)

• Carbon (C): 0.12 – 0.22
• Silicon (Si): ≤ 1.0
• Manganese (Mn): ≤ 1.5
• Phosphorus (P): ≤ 0.040
• Sulfur (S): ≤ 0.030
• Chromium (Cr): 15.0 – 17.0
• Nickel (Ni): 1.5 – 2.5

💡 The increased chromium content ensures excellent corrosion resistance and mechanical fatigue strength.

🏭 Applications

Steel AISI 431 (EN 1.4057) is widely used in manufacturing components that operate under high mechanical and corrosive stress conditions.

Main Application Areas:

• Shipbuilding and marine engineering.
• Aerospace and automotive industries.
• Production of pumps, valves, turbines, and other industrial equipment.
• Medical equipment and instruments.
• Manufacturing of high-wear-resistant parts (shafts, spindles, screws, bearings).

📊 Mechanical Properties

• Tensile Strength (Rm): 850 – 1000 MPa
• Yield Strength (Rp0.2): ≥ 500 MPa
• Hardness (HB): 250 – 300 HB (after heat treatment)
• Elongation (A5): ≥ 12 %

⭐ Features

• High strength and hardness – after quenching, the steel becomes extremely strong and wear-resistant.
• Corrosion resistance – performs well in fresh water, outdoor environments, and moderately aggressive chemical conditions.
• Good machinability – suitable for mechanical processing and polishing.
• Heat treatability – improved mechanical properties through hardening and tempering.
• Limited weldability – requires preheating before welding and post-weld heat treatment.

💡 AISI 431 is an ideal choice for components that operate under high loads and require a combination of strength, corrosion resistance, and durability.

AISI 431 / EN 1.4057 steel delivery forms