Stainless steel 9.9440 / AISI 440A

✅ General Technical Characteristics

Stainless steel 9.9440 (AISI 440A) is a high-carbon martensitic stainless steel that combines excellent corrosion resistance with high hardness. Due to its structure, it is suitable for heat treatment, which significantly enhances its mechanical strength and wear resistance. This material is widely used for manufacturing cutting tools, bearings, and high-load components.
Main Characteristics:
High hardness and strength after heat treatment.
Excellent wear resistance and durability.
Corrosion resistance in moderate environments.
Good machinability and polishability.
Heat resistance and stability of mechanical properties under high loads.
🔬 Chemical Composition 9.9440 / AISI 440A (%)Carbon (C): 0.60 – 0.75
Silicon (Si): ≤ 1.0
Manganese (Mn): ≤ 1.0
Phosphorus (P): ≤ 0.040
Sulfur (S): ≤ 0.030
Chromium (Cr): 16.0 – 18.0
Nickel (Ni): ≤ 0.75
Molybdenum (Mo): ≤ 0.75
💡 The high carbon content provides additional hardness, while chromium ensures corrosion resistance.
🏭 Applications

Due to its high hardness and wear resistance, 9.9440 (AISI 440A) steel is widely used in various industries that require a combination of strength and corrosion resistance.
Main Application Areas:
Production of knives and blades.
Medical and surgical instruments.
Manufacturing of bearings and bushings.
Components for pump equipment.
Tool industry (cutters, drills, scalpels).
📊 Mechanical Properties

Tensile Strength (Rm): 750 – 900 MPa
Yield Strength (Rp0.2): ≥ 450 MPa
Hardness (HB): 250 – 300 HB (after heat treatment)
Elongation (A5): ≥ 20 %
⭐ Features

High hardness – achieved after quenching, making the steel ideal for cutting tools.
Wear resistance – resistant to abrasion and mechanical damage.
Corrosion resistance – performs well against moisture and moderately aggressive environments.
Heat treatability – can be hardened to increase strength.
Durability – maintains stable mechanical properties even under intensive use.

AISI 440A steel delivery forms