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Product Overview
INTRODUCTION TO STAINLESS STEEL 440B / AISI 440B / UNS S44004
Stainless Steel 440B (UNS S44004) is a high-carbon martensitic stainless steel offering higher hardness and wear resistance than 440A after heat treatment, while retaining moderate corrosion resistance in mildly corrosive environments. It is fully magnetic and can be hardened by conventional quench-and-temper cycles, making it suitable for blades, wear parts, and precision components.
MOKSH TUBES & FITTINGS LLP is a trusted supplier, exporter, importer, and stockist of stainless 440B products, including pipes, tubes, fittings, flanges, fasteners, sheets, plates, coils, wires, bars, and custom machined parts, produced to international standards for performance and reliability.
Compared to lower-carbon grades, 440B delivers excellent edge retention, high surface hardness up to 56–60 HRC when properly heat treated, and good polishability for cutting tool and industrial service applications where both hardness and oxidation resistance are required.
For weight-critical designs, note typical steel density of 7.85 g/cm³ versus 440B density 7.65 g/cm³, which can slightly reduce component mass without compromising mechanical performance when properly heat treated and finished.
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Material Summary – SS 440B / UNS S44003
| Property | Details |
|---|---|
| Material Type | High-Carbon Martensitic Stainless Steel |
| UNS Designation | S44003 |
| AISI | 440B |
| Chromium Content | 16.0 – 18.0 % |
| Carbon Content | 0.75 – 0.95 % |
| Heat Treatable | ✔ Yes (Quench & Temper) |
| Maximum Hardness | 56 – 60 HRC |
| Wear Resistance | Very Good |
| Corrosion Resistance | Moderate |
| Magnetic Property | Fully Magnetic |
| Typical Density | ~7.65 g/cm³ |
👉 The higher carbon content gives SS 440B superior hardness and wear resistance compared to 440A, while maintaining reasonable corrosion resistance.
Chemical Composition of SS 440B
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.75 – 0.95 |
| Manganese (Mn) | ≤ 1.00 |
| Silicon (Si) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.04 |
| Sulfur (S) | ≤ 0.03 |
| Chromium (Cr) | 16.0 – 18.0 |
| Molybdenum (Mo) | ≤ 0.75 |
| Iron (Fe) | Balance |
Technical Composition of SS 440B
Physical Properties of SS 440B
| Property | Value |
|---|---|
| Density | 7.65 g/cm³ |
| Melting Point | 1480 – 1530 °C |
| Modulus of Elasticity | 200 GPa |
| Thermal Conductivity | 24 W/m·K (100 °C) |
| Electrical Resistivity | 0.60 µΩ·m |
| Magnetic Properties | Fully Magnetic (Martensitic) |
Heat Treatment & Hardening Cycle – SS 440B
| Process | Temperature Range | Purpose |
|---|---|---|
| Annealing | 840 – 900 °C | Improves machinability |
| Hardening (Austenitizing) | 1010 – 1065 °C | Forms martensitic structure |
| Quenching | Oil / Air | Achieves high hardness |
| Cryogenic Treatment | −70 to −196 °C | Improves wear & dimensional stability |
| Tempering | 150 – 370 °C | Balances hardness & toughness |
| Stress Relieving | 600 – 650 °C | Reduces internal stresses |
📌 SS 440B is positioned between 440A and 440C, offering excellent edge retention after precise quench & temper cycles.
Mechanical Properties of SS 440B
| Property | Metric | Imperial |
|---|---|---|
| Tensile Strength | 655 – 895 MPa | 95,000 – 130,000 psi |
| Yield Strength (0.2%) | ~415 MPa | ~60,000 psi |
| Elongation | 15 – 20% | 15 – 20% |
| Hardness (Annealed) | 215 – 235 HB | 215 – 235 HB |
| Hardness (Hardened) | 56 – 60 HRC | |
👉 SS 440B achieves high surface hardness and excellent edge retention, making it ideal for blades and wear-resistant components.
International Standards & Equivalent Grades – SS 440B
| Standard | Equivalent Grade |
|---|---|
| UNS | S44003 |
| AISI | 440B |
| EN | 1.4122 |
| DIN | X90CrMoV18 |
| ASTM | A276, A314, A580 |
| JIS | SUS 440B |
| ISO | X90CrMoV18 |
Products in Stainless Steel 440B
MOKSH TUBES & FITTINGS LLP, with extensive experience in martensitic stainless steels, supplies Stainless Steel 440B in a broad range of product forms for industrial, mechanical, and precision applications. Known for its excellent hardness, wear resistance, and moderate corrosion protection, 440B serves as a versatile material for engineering and production environments that demand high performance.
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Seamless Pipes
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Welded Pipes (ERW & EFW)
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Tubes (Capillary, Instrumentation, Heat Exchanger)
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Sheets & Plates
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Coils & Strips
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Round Bars, Flat Bars, Hex Bars, Square Bars
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Pipe Fittings (Elbows, Tees, Reducers, Caps, Stub Ends)
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Flanges (Weld Neck, Slip-On, Blind, Socket Weld, Threaded)
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Fasteners (Bolts, Nuts, Screws, Washers, Studs)
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Precision Machined & Heat-Treated Components
All products comply with international standards such as ASTM A276 / A314 / A580 to ensure top-quality material performance and dimensional accuracy.
