440B steel is a high-carbon martensitic stainless steel, known for its excellent hardness after heat treatment, good overall strength, moderate corrosion resistance, and excellent wear resistance.
The alloy must be kept free from oxides and contaminants to maximize corrosion resistance. After heat treatment, the material can achieve a hardness exceeding 60 HRC, comparable to the performance of a tool steel.

Reference Standard:

• ASTM A276 (bars, plates, sheets)
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Chemical composition (%)

Element Min (%) Max (%)
Carbon (C) 0.75 0.95
Manganese (Mn) – 1.00
Phosphorus (P) – 0.04
Sulfur (S) – 0.03
Silicon (Si) – 1.00
Chromium (Cr) 16.0 18.0
Molybdenum (Mo) – 0.75
Iron (Fe) Balance
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Mechanical properties

Property Value
0.2% Yield Strength (at 20°C) 1860 N/mm²
Elongation over 50.8 mm 3%
Reduction of Area 15%
Hardness (hot-rolled supply) ≤269 HBW (28 HRC)
Hardness (cold-rolled supply) ≤285 HBW (30 HRC)
Hardness after heat treatment ≥56 HRC
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Key Properties

• Excellent hardness after heat treatment (>60 HRC possible).
• Excellent wear resistance.
• Good overall strength.
• Performance similar to tool steels.
• Moderate corrosion resistance.
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Available forms

• Round bars
• Plates
• Sheets
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Industrial applications

Thanks to its high hardness and wear resistance, 440B is used in:
• Valves and valve seats
• Cutting tools and knife blades
• Bearings
• Surgical instruments
• Components subject to high abrasion