About Alloy
Stainless steel grade 440A is a high carbon martensitic stainless steel that possesses good strength, moderate corrosion resistance, and excellent hardness and wear resistance.
Manufacturing Process:
Stainless steel grade 440A can be easily machined in the annealed condition. Carbide or ceramic tooling is recommended for performing machining. Chip breakers enable easy handling of tough stringy chips. As this steel has the tendency to air harden, welding is not performed; however if it is required, the steel should be preheated to 260°C (500°F) and post-weld treated at 732-760°C (1350-1400°F) for 6 h. This is followed by a slow furnace cooling to avoid cracking.
Grade 440A stainless steel is annealed at 843-871°C (1550-1600°F), followed by very slow furnace cooling. For performing hot working, the materials needs to be preheated to 760°C (1400°F) and then slowly increased to 1038-1204°C (1900-2200°F) before proceeding. The material should then be cooled slowly after working and once again cooled at room temperature. Finally it must be annealed fully. This material should not be heated below 927°C (1700°F).
For performing tempering, grade 440A should be soaked at 148°C (300°F). Similarly for hardening, the material should be heated slowly to 760°C (1400°F), then soaked at 1010°C (1850°F), finally air or oil cooled.
Product Form & Standard
AMS 5631: Bars / wire / forgings
AMS 5632: 440F Bars / forging
Chemical Composition
| Element | Content (%) |
| Iron, Fe | Balance |
| Chromium, Cr | 16-18 |
| Manganese, Mn | 1 |
| Silicon, Si | 1 |
| Molybdenum, Mo | 0.75 |
| Carbon, C | 0.60-0.75 |
| Sulfur, S | 0.03 |
| Phosphorous, P | 0.04 |
Mechanical Properties
| Properties | Metric | Imperial |
| Tensile strength | 725-1790 MPa | 105000 - 260000 psi |
| Yield strength (@strain 0.200 %) | 415-1650 MPa | 60200 - 239000 psi |
| Modulus of elasticity | 204 - 215 GPa | 29600 - 31200 ksi |
| Elongation at break (in 50 mm) | 5- 20% | 5- 20% |
| Hardness, Rockwell B | 95 | 95 |
Application
Grade 440A stainless steel is widely used in the following applications:
Cutlery
Bearings
Gage blocks
Molds and dies
Valve components
Turbine components
Medical instruments
Aircraft structural parts
Knives and measuring instruments
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