SUS420J2 vs. 440C Stainless Steel: Key Differences
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What material is SUS420J2 stainless steel bar ?
SUS420J2 is a Japanese Standard (JIS) martensitic stainless steel known for its high hardness, wear resistance, and moderate corrosion resistance. It contains 12-14% chromium and 0.26-0.40% carbon. It is a magnetic steel, typically supplied in the annealed state, and is commonly used in cutting tools, surgical instruments, and industrial machinery parts. Its performance is comparable to AlSI 420.
what is 440C Stainless Steel bar?
440C stainless steel bar is a high-carbon, martensitic chromium steel designed to achieve the highest strength, hardness, and wear resistance of any stainless alloy after heat treatment. It is widely used in high-wear environments, including bearings, cutlery, and surgical instruments. Common synonyms include AISI 440C, 1.4125 stainless, and SUS440C.
SUS420J2 vs. 440C Stainless Steel: Chemical Composition (Typical Weight %)
| Element | SUS420J2 (%) | AISI 440C (%) |
| Carbon (C) | 0.26 – 0.40 | 0.95 – 1.20 |
| Chromium (Cr) | 12.00 – 14.00 | 16.00 – 18.00 |
| Manganese (Mn) | ≤ 1.00 | ≤ 1.00 |
| Silicon (Si) | ≤ 1.00 | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.040 | ≤ 0.040 |
| Sulphur (S) | ≤ 0.030 | ≤ 0.030 |
| Molybdenum (Mo) | - | 0.75 (Optional/Max) |
| Nickel (Ni) | ≤ 0.60 (Optional) | - |
SUS420J2 vs. 440C Stainless Steel: Mechanical & Physical Properties
| Property | SUS420J2 | AISI 440C |
| Hardness (Rockwell C) | 50 – 54 HRC | 58 – 62 HRC |
| Tensile Strength | ≥ 735 MPa | ≥ 760 - 1900 MPa (Heat treat dependent) |
| Yield Strength | ≥ 540 MPa | ≥ 450 - 1800 MPa |
| Elongation | ≥ 12% | ≥ 2 - 5% (Brittle) |
| Density | 7.75 g/cm³ | 7.65 g/cm³ |
| Elastic Modulus | 200 GPa | 200 GPa |
SUS420J2 vs. 440C Stainless Steel: Heat Treatment
| Process | SUS420J2 | 440C Stainless Steel |
|---|---|---|
| Annealing | 750°C fast cool or 800–900°C slow cool | 800–850°C (1470–1560°F), slow cool |
| Quenching | 980–1040°C fast cooling (air or oil) | 1020–1050°C (1870–1920°F), air or oil quench |
| Tempering | 150–400°C (air cooling) | 200–300°C (390–570°F) |
| Final Hardness | ~50–55 HRC | ~58–60+ HRC |
SUS420J2 vs. 440C Stainless Steel: Hardness and Sharpness Retention
The carbon content of 440C (0.95%–1.20%) is significantly higher than that of 420J2 (0.26%–0.40%). This allows 440C to achieve a hardness of 58–60 HRC after heat treatment, while 420J2 typically only reaches a maximum of 52–55 HRC. 440C is generally considered a higher-end, harder, and more durable blade steel, while 420J2 is a more affordable option, often used in entry-level kitchen knives.
SUS420J2 vs. 440C Stainless Steel: Corrosion Resistance
SUS420J2 generally offers superior corrosion resistance to 440C due to lower carbon content, making it better for wet environments, though 440C is far harder and more wear-resistant. SUS420J2 is suitable for mild corrosion exposure (cutlery, diving knives), while 440C is better for high-performance blades.
SUS420J2 vs. 440C Stainless Steel: Toughness and Durability
SUS420J2 stainless steel bars are not easily broken when subjected to sudden impact or stress. They are often used in applications where corrosion resistance and toughness are more important than long-lasting sharpness. 440C, a high-carbon steel, has a higher hardness (HRC 58-60) after heat treatment and has excellent wear resistance and edge retention, making it more "durable" in cutting applications, but it is more brittle than 420J2.
SUS420J2 vs. 440C Stainless Steel: Machinability
The machinability of 420 series stainless steel is approximately 45% to 50% that of standard carbon steel (B1112). It is considered to have medium machinability, similar to medium carbon steel, making it easier to perform machining operations such as turning and milling. 440C stainless steel has lower machinability, approximately 35% to 40% that of standard carbon steel. Its high chromium carbide content leads to rapid tool wear, making it more difficult to machine.
SUS420J2 vs. 440C Stainless Steel:Applications
SUS420J2: Best forbudget-friendly knives, kitchen cutlery, scissors, diving knives, and industrial components where high rust resistance and durability are preferred over extreme edge retention.
440C: Best for high-end hunting knives, tactical knives, bearings, surgical tools, and cutlery requiring exceptional sharpness and wear resistance.
SUS420J2 stainless steel bar supplier
GNEE Stainless Steel has exported high-precision SUS420J2 and 440C bars to over 70 countries, including Germany, South Korea, and the United States. We maintain a 500-ton inventory, export over 2000 tons annually, and boast a 98.5% on-time delivery rate, ensuring a stable supply chain for our customers. Each batch undergoes 100% PMI chemical composition analysis and ultrasonic testing (SEP 1921 C/c grade) to guarantee zero internal defects and comes with a complete EN 10204 3.1 factory test certificate.
Product Shapes & Size Range
| Product Form | Size Range | Process |
|---|---|---|
| Round Bar | Φ 2 mm – Φ 600 mm | Cold Drawn, Hot Rolled, Forged |
| Hexagonal Bar | S 4 mm – S 100 mm | Cold Drawn, Hot Rolled |
| Square Bar | 4 mm × 4 mm – 200 mm × 200 mm | Cold Drawn, Forged |
| Flat Bar | Thickness: 2 mm – 100 mm; Width: 10 mm – 500 mm | Hot Rolled, Cut from Plate |
Delivery Condition & Heat Treatment:
For martensitic stainless steels (SUS420J2 and 440C), GNEE can provide different hardness conditions according to customer requirements:
Annealed - Soft: Facilitates machining, drilling, and other processing.
Quenched & Tempered - Q+T: Pre-hardened treatment, directly achieving the usable hardness, reducing the risk of deformation during subsequent heat treatment.
Hardened: Provides high-hardness bars for specific needs.
Packaging and Logistics:
Standard export packaging (wooden crates, woven bags, and bundling).
Sea freight, air freight, and international express (DHL/FedEx) are supported.
