Product Description
Stainless steels are high-alloy steels which have high corrosion resistance compared to other steels due to the presence of large amounts of chromium. Based on their crystalline structure, they are divided into three types such as ferritic, austenitic, and martensitic steels. Another group of stainless steels are precipitation-hardened steels. They are a combination of martensitic and austenitic steels.
Type 440C (UNS S44004) is a martensitic stainless steel with high carbon and chromium content. Molybdenum improves the steel deep hardening and toughness. It also enhances wear resistance. After heat treatment, it is capable of attaining the highest strength, hardness and wear resistance of all stainless alloys.
Grade 440C stainless steel is a high carbon martensitic stainless steel. It has high strength, moderate corrosion resistance, and good hardness and wear resistance. Grade 440C is capable of attaining, after heat treatment, the highest strength, hardness and wear resistance of all the stainless alloys. Its very high carbon content is responsible for these characteristics, which make 440C particularly suited to such applications as ball bearings and valve parts.
Chemical Composition
| Grade |
| 440C |
| C | Mn | Si | P | S | Cr | Mo | Ni | N | |
| min. max. |
0.95 1.20 |
- 1 |
- 1 |
- 0.04 |
- 0.030 |
16.00 18.00 |
- 0.75 |
- | - |
Mechanical Properties
| Tempering Temperature
(°C) |
Tensile Strength
(MPa) |
Yield Strength 0.2% Proof
(MPa) |
Elongation
(% in 50mm) |
Hardness
(HR C) |
| Annealed* | 758 | 448 | 14 | 269HB max# |
| 204 | 2030 | 1900 | 4 | 59 |
| 260 | 1960 | 1830 | 4 | 57 |
| 316 | 1860 | 1740 | 4 | 56 |
| 371 | 1790 | 1660 | 4 | 56 |
| * Annealed properties are typical for Condition A of ASTM A276# Brinell Hardness is ASTM A276 specified maximum for annealed 440A, B and C. |
Physical Properties
| Elastic Modulus
(GPa) |
Mean Coefficient of Thermal Expansion
(mm/m/°C) |
Thermal Conductivity
(W/m.K) |
|||
| 0-100°C | 0-200°C | 0-600°C | at 100°C | at 500°C | |
| 200 | 10.1 | 10.3 | 11.7 | 24.2 | - |
Physical Properties
| Grade | Why it might be chosen instead of 440C |
| 440A/B | Slightly softer and more corrosion resistant grade needed |
| 440F | High machinability required, with same hardness and hardenability as 440C |
| 420 | Lower strength and hardness needed than any of the 440 grades |
| 416 | Higher machinability required, and the much lower hardness and strength is still adequate |
Applications
