Description
Martensitic Stainless Steel 440A, 440B, 440C
WHAT IS 440C material?
Stainless Steel 440C ( 1.4125 ) 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 SS440C particularly suited to such applications as ball bearings and valve parts.
- Hardenable high-carbon chromium steels designed to provide stainless properties with maximum hardness
- Have maximum hardness together with high strength and corrosion resistance in the hardened and stress relieved condition
- Always used in the hardened or hardened and stress relieved conditions
- None of the alloys has its full corrosion resistance either in the annealed or in the hardened and tempered condition
- Wide applications where good corrosion resistance along with high hardness or abrasion resistance is required
440C stainless steel equivalent
| Country | USA | BS & DIN | Japan |
| Standard | ASTM A276 | EN 10088 | JIS G4303 |
| Grades | S44004/440C | X105CrMo17/1.4125 | SUS440C |
ASTM 440C Stainless Steel 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 |
Applications of stainless Steel 440C
- Used in numerous applications in areas where a very hard and abrasion resistant stainless is called for
- Applications include pivot pins, dental and surgical instruments, cutlery valve parts, ball bearings, nozzles, hardened steel balls and seats for oil well pumps, plus valve parts
Will 440C stainless steel rust?
These stainless steels have good corrosion resistance in the hardened and stress relieved conditions. Hence, they should, usually, be used only in that condition. These steels are resistant to such conditions as fresh water, steam, crude oil, gasoline, perspiration, and alcohol.
| Composition | |||
| Property | SS 440A | SS 440B | SS 440C |
| Carbon | .60 – .75 | .75 – .95 | .95 – 1.2 |
| Manganese | 1.00 max | 1.00 max | 1.25 max |
| Silicon | 1.00 max | 1.00 max | 1.00 max |
| Phosphorus | .04 max | .04 max | .04 max |
| Sulfur | .03 max | .03 max | .04 max |
| Chromium | 16.0 – 18.0 | 16.0 – 18.0 | 16.5 – 18.0 |
| Molybdenum | .75 max | .75 max | .75 max |
| Nickel | .50 max | NA | NA |
Hardening of 440C Steel
Stainless steel 440C grade can be hardened by heating at 760°C (1400°F). Temperature can be increased up to 1010°C (1850°F) followed by quenching in warm oil or cool in air. However, don’t overheat, because when overheated, full hardness cannot be obtained.
440c stainless steel Heat Treatment
PROCESS ANNEAL: Heat at 1350-1450° F then cool very slowly in the furnace.
FULL ANNEAL: Heat uniformly at 1550-1600° F soak and cool slowly in furnace to 1000-1250° F at a rate of 20-50° F per hour, then cool in air, oil, or water.
HARDENING: Preheat slowly to 1450° F and soak, then raise temperature to 1850-1950° F, quench in warm oil or air. Products hardness of C55-58 Rockwell.
STRESS RELIEVE: Heat to 300-800° F for 1 to 3 hours, air cool.
