When it comes to premium stainless steel, 440C steals the spotlight. In this comprehensive guide, we’ll explore the intricate details of 440C steel—covering specifications, chemical composition, physical and mechanical properties, applications, steel equivalents. Whether you’re a seasoned buyer or a curious visitor, this guide aims to demystify 440C and empower you with the knowledge needed to make informed decisions.
440C Steel General Properties
440C Stainless Steel, designated as UNS S44000 and DIN 1.4125/X105CrMo17, belongs to the high-alloy martensitic stainless steels with excellent corrosion resistance, particularly due to its high chromium content. It falls under the category of precipitation-hardened steels, combining characteristics of both martensitic and austenitic steels.
Corrosion Resistance
440C demonstrates good resistance to various environments, including the atmosphere, fresh water, foods, alkalies, and mild acids. The highest resistance is achieved in the hardened, tempered, and passivated condition, with a smooth polished surface further enhancing corrosion resistance. In many environments, its corrosion resistance is comparable to grade 304.
Heat Resistance
440C is not recommended for use in temperatures exceeding the relevant tempering temperature to prevent a reduction in mechanical properties due to over-tempering.
440C Steel Heat Treatment
Annealing:
– Full Anneal: 850-900°C, slow furnace cool to about 600°C, then air cool.
– Sub-critical Annealing: 735-785°C, followed by a slow furnace cool.
Hardening:
– Heat to 1010-1065°C, quench in warm oil or air.
– Immediate tempering at 150-370°C to achieve a range of hardness values.
440C Steel Welding
If welding is necessary, pre-heat at 250°C and follow welding with a full anneal. Grade 420 filler produces a high-hardness weld, while 309 or 310 yields soft welds with higher ductility.
440C Steel Machining
440C is relatively easily machined in the annealed condition, comparable to high-speed steel. However, machining becomes more challenging, potentially impossible, after hardening.
440C Steel Mechanical Properties
| Tempering Temperature (°C) | Tensile Strength (MPa) | Yield Strength 0.2% Proof (MPa) | Elongation (% in 50mm) | Hardness Rockwell (HRC) | Impact Charpy V (J) |
| Annealed* | 758 | 448 | 14 | 269HB max# | – |
| 204 | 2030 | 1900 | 4 | 59 | 9 |
| 260 | 1960 | 1830 | 4 | 57 | 9 |
| 316 | 1860 | 1740 | 4 | 56 | 9 |
| 371 | 1790 | 1660 | 4 | 56 | 9 |
440C Stainless steel Physical Properties
| Grade | Density (kg/m3) | Elastic Modulus (GPa) | Mean Coefficient of Thermal Expansion (mm/m/°C) | Thermal Conductivity(W/m.K) | Specific Heat | Electrical Resistivity (nW.m) | |||
| 0-100°C | 0-200°C | 0-600°C | at 100°C | at 500°C | 0-100°C (J/kg.K) | ||||
| 440 C | 7650 | 200 | 10.1 | 10.3 | 11.7 | 24.2 | – | 460 | 600 |
440C Stainless steel Equivalent and Chemical Composition
| Standard | Grade | C | Mn | P | S | Si | Cr | Mo |
| ASTM A276 | S44004/440C | 0.95-1.20 | ≦1.00 | ≦0.04 | ≦0.03 | ≦1.00 | 16.0-18.0 | ≦0.75 |
| EN10088 | X105CrMo17/1.4125 | 0.95-1.20 | ≦1.00 | ≦0.04 | ≦0.03 | ≦1.00 | 16.0-18.0 | 0.40-0.80 |
| JIS G4303 | SUS 440C | 0.95-1.20 | ≦1.00 | ≦0.04 | ≦0.03 | ≦1.00 | 16.0-18.0 | ≦0.75 |
Possible Alternative Grades
– 440A/B: Slightly softer and more corrosion-resistant.
– 440F: High machinability with similar hardness and hardenability.
– 420: Lower strength and hardness.
– 416: Higher machinability with lower hardness and strength.
Grade Characteristics
440C exhibits high strength, moderate corrosion resistance, and exceptional hardness and wear resistance, especially after heat treatment. Its elevated carbon content contributes to its outstanding properties, making it suitable for applications like ball bearings and valve parts.
440C Stainless Steel Applications :
– Rolling element bearings
– Valve seats
– High-quality knife blades
– Surgical instruments
– Chisels
Conclusion
In conclusion, 440C stainless steel is not just a material; it’s a solution to your durability and performance needs. Whether you’re in the market for cutlery, aerospace components, or medical instruments, 440C stands as a reliable and versatile choice.
Want to know more about the 440C steel details ?
Pls contact : Joann
E-mail:joann@otaisteel.com
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