AISI 303 stainless steel is a free-machining austenitic stainless steel designed for efficient production of precision components. It offers good machinability and moderate corrosion resistance for general industrial applications.
AISI 303 is an austenitic stainless steel modified to improve machinability, making it especially suitable for manufacturing complex components through turning, drilling, and other machining processes. Its composition supports efficient production of precision parts while retaining useful corrosion resistance in many general industrial environments.
It is commonly used for fittings, fasteners, shafts, valve components, connectors, and CNC-machined parts. Compared with 304 stainless steel, its sulfur content improves machining performance but generally reduces corrosion resistance and weldability. The grade should be selected according to the operating environment and fabrication requirements. Typical Applications: CNC components, fittings, fasteners, shafts, connectors, and precision-machined parts.Final chemical, mechanical properties, dimensions and tolerances are confirmed against the governing specification and purchase order.
| Element | Symbol | Min (%) | Max (%) | Nominal Target |
|---|---|---|---|---|
| Chromium | Cr | 17.00% | 19.00% | 18.00% |
| Nickel | Ni | 8.00 | 10.00% | 9.00% |
| Carbon | C | — | 0.15% | Max 0.15% |
| Manganese | Mn | — | 2.00% | 1.50% |
| Sulfur | S | 0.15% | 0.35% | 0.25% |
| Silicon | Si | — | 1.00% | 0.50% |
| Phosphorus | P | — | 0.20% | Max 0.20% |
| Iron | Fe | Balance | Balance | ~69.0% |
| Property | Metric Value | Imperial Value |
|---|---|---|
| Tensile Strength (Ultimate) | 515 – 620 MPa | 75,000 – 90,000 psi |
| Yield Strength | 205 – 240 MPa | 30,000 – 35,000 psi |
| Elongation at Break (in 50 mm) | 35% – 50% | 35% – 50% |
| Reduction of Area | 45% – 60% | 45% – 60% |
| Hardness (Brinell - HBW) | 160 – 190 HB | 160 – 190 HB |
| Hardness (Rockwell B - HRB) | 83 – 90 HRB | 83 – 90 HRB |
| Modulus of Elasticity (Young's) | 193 GPa | 28,000 ksi |
| Density | 8.03 g/cm³ | 0.290 lb/in³ |
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