AISI 303 Stainless Steel Properties, SS 303 Density, Hardness, Magnetic, Equivalent (UNS S30300)
AISI 303 Stainless Steel (UNS S30300, SS 303)
AISI 303 stainless steel (UNS S30300) was developed for easy cutting and basically belongs to 18-8 stainless steel. It improves the cutting performance while maintaining good mechanical properties. SS 303 material has a higher sulfur content, which reduces the resistance on the cutting tool, but has a negative impact on the corrosion resistance, so the corrosion resistance is not as good as AISI 304 stainless steel.
Type 303 Stainless Steel Properties
The following datasheet give 303 stainless steel properties including chemical composition, physical and mechanical properties, heat treatment, welding, etc.
Chemical Composition
SS 303 material chemical composition is listed in the following table based on cast analysis.
| Chemical Composition, % | |||||||||
| ASTM | AISI (UNS) | C, ≤ | Si, ≤ | Mn, ≤ | P, ≤ | S, ≥ | Cr | Ni | Notes |
| ASTM A582/A582M | 303 (UNS S30300) | 0.15 | 1.00 | 2.00 | 0.20 | 0.15 | 17.0-19.0 | 8.0-10.0 | Free-Machining Stainless Steel Bars |
| ASTM A581/A581M | Free-Machining Stainless Steel Wire and Wire Rods | ||||||||
| ASTM A895 | Free-Machining Plate, Sheet, and Strip | ||||||||
| ASTM A959 | Wrought Stainless Steels | ||||||||
| ASTM A473 | Stainless Steel Forgings | ||||||||
| ASTM A314 | Billets and bars for forging | ||||||||
Notes:
- ASTM A582/A582M: Standard Specification for Free-Machining Stainless Steel Bars
- ASTM A581/A581M: Standard Specification for Free-Machining Stainless Steel Wire and Wire Rods
- ASTM A895: Standard Specification for Free-Machining Stainless Steel Plate, Sheet, and Strip
- ASTM A959: Standard Guide for Specifying Harmonized Standard Grade Compositions for Wrought Stainless Steels
- ASTM A473: Standard Specification for Stainless Steel Forgings
- ASTM A314: Standard Specification for Stainless Steel Billets and Bars for Forging
Physical Properties
AISI 303 stainless steel physical properties are given in the following lists, including density, thermal expansion, elastic modulus, thermal conductivity, specific heat capacity and electrical resistance.
Notes:
- 10-6·K-1 = 10-6/K
- 1 Ω·mm²/m = 1 μΩ·m
- 1 g/cm3 = 1 kg/dm3 = 1000 kg/m3
- 1 GPa = 1 kN/mm2
- 1 MPa = 1 N/mm2
| Physical Properties | |
| 303 stainless steel density, g/cm3 (lb/in.3) | 7.9 (0.29) |
| Melting point, °C (°F) | 1400-1450 (2550-2590) |
| Specific heat capacity, J/kg·K (Btu/lb ·°F) | 500 (0.12) at 20℃ |
| Electrical resistivity, μΩ·m | 0.72 at 20℃ |
| Magnetic permeability | 1.02 (Approximate) |
| Elastic modulus, GPa (106 psi) | 193 (28) |
| Thermal conductivity, W/m·K (Btu/ft · h ·°F) | 16.2 (9.4) at 100 °C (212 °F) |
| 21.5 (12.4) at 500 °C (932 °F) | |
| Coefficient of thermal expansion, 10-6/K (μin./in. ·°F) | 17.2 (9.6) at 0-100 ℃ (32-212 °F) |
| 17.8 (9.9) at 0-315 ℃ (32-600 °F) | |
| 18.4 (10.2) at 0-538 ℃ (32-1000 °F) | |
Magnetic: SS 303 is non-magnetic in the annealed condition, but may become slightly magnetic due to cold working.
Mechanical Properties
303 steel mechanical properties at room temperature are listed in the following tables.
| AISI 303 Mechanical Properties | ||||||
| ASTM | AISI | Conditions | Tensile Strength, MPa (ksi), ≥ | 0.2% Yield Strength, MPa (ksi), ≥ | Elongation in 50 mm (2 in.), %, ≥ | Reduction of Area, %, ≥ |
| ASTM A473 | 303 (UNS S30300) | Annealed | 515 (75) | 205 (30) | 40 | 50 |
| ASTM A581/A581M | Annealed | 585-860 (85-125) | ||||
| Cold Worked | 795-1000 (115-145) | |||||
Brinell Hardness:
- 160, Annealed bar
- 228, Cold drawn
Heat Treatment
Recommended annealing temperatures for AISI 303 wrought stainless steel is 1040 °C (1900 °F).
Typical forging temperature range is 925-1260 °C (1700-2300 °F), (C: 0.08%; S: 0.30%)
Hardening: SS 303 cannot be hardened by heat treatment, but can be hardened by cold working.
Welding
Due to the high P and S content, SS 303 material is not recommended for welding. If welding cannot be avoided, AWS E312 filler metal may be considered.
Machinability (Machining)
Increased tool life attained with coated cutting tools
| Cutting tool | Coating | Workpiece material | Workpieces machined before resharpening | ||
| Type | High-speed tool steel, AISI type | Uncoated | Coated | ||
| Broach insert | M3 | TiN | Type 303 stainless steel | 100,000 | 300,000 |
| Form tool | T15 | TiN | 1,840 | 5,890 | |
Recommended face angles, along with backoff angles for type 303 stainless steel:
- Face angle, 15 degrees;
- Backoff angle:0.5 – 2 degrees.
Speed and feed ranges for the spade drilling are listed in the following table.
| Material drilled | Drill diameter, mm (in.) | |||||||||
| 25 (1) | 50 (2) | 75 (3) | 100 (4) | 125 (5) | ||||||
| Speed, rev/min | Feed rate, mm/rev (in./rev) | Speed, rev/min | Feed rate, mm/rev (in./rev) | Speed, rev/min | Feed rate, mm/rev (in./rev) | Speed, rev/min | Feed rate, mm/rev (in./rev) | Speed, rev/min | Feed rate, mm/rev (in./rev) | |
| Type 303 and 303 Se | 225-275 | 0.15-0.25 (0.006-0.010) | 120-125 | 0.25-0.38 (0.010-0.015) | 75-90 | 0.38-0.51 (0.015-0.020) | 55-65 | 0.51-0.63 (0.020-0.025) | 45-55 | 0.63-0.76 (0.025-0.030) |
Recommended cutting parameters for indexable drills with uncoated and titanium-coated carbide inserts
| Material | Drill size | Speed | Feed | Insert style | Grade | |||||
| Standard length | Stub length | |||||||||
| mm | in. | m/min | sfm | m/min | sfm | mm/rev | in./rev | |||
| AISI 303, 304 and 316, 416 | 19-30 | .75 – 1.1875 | 45-105 | 150-350 | 45-150 | 150-500 | 0.08-0.10 | 0.003-0.004 | SPGM | C-2, Uncoated |
| 32-36.5 | 1.25-1.4375 | 0.10-0.13 | 0.004-0.005 | SNMG | C-5, Titanium coated. | |||||
| 38-47.5 | 1.50-1.875 | 0.10-0.15 | 0.004-0.006 | SNMMND | ||||||
| 49-75 | 1.9375-3 | 0.13-0.20 | 0.005-0.008 | SNMMND | ||||||
Nominal speeds and feeds for thread milling with high-speed steel tools
| Work material | Hardness, HB | Speed | Feed | ||
| m/min | sfm | mm/tooth | in./tooth | ||
| Type 303 | 135-185 | 30 | 100 | 0.05 | 0.002 |
| 225-275 | 27 | 90 | 0.04 | 0.0015 | |
Nominal speeds for die cutting of screw threads
| Work metal | Speed for pitch of | |||||||
| ≤ 7 | 8-15 | 16-24 | ≥ 25 | |||||
| m/min | sfm | m/min | sfm | m/min | sfm | m/min | sfm | |
| Types 303, 410, 420F, 440F | 3 | 10 | 4.5 | 15 | 6 | 20 | 7.5 | 25 |
Nominal speed, cutting rate, and band life for the cutoff band sawing of steel bars
| Steel being cut | Hardness, HB | Band speed | Cutting rates | Band life in terms of total area cut | |||
| m/min | sfm | mm2 x 103/min | in.2/min | mm2 × 106 | in.2 × 103 | ||
| SS 303, 303F | 150-200 | 40-27 | 130-90 | 3.2-1.3 | 5-2 | 2.1 | 3.3 |
Use & Application
SS303 material is mainly used for parts that need machining, grinding or polishing, suitable for rapid cutting to make rolls, shafts, bolts, nuts, etc.
Equivalent Material
SS 303 stainless steel equivalent materials are listed in the datasheet below, including European (German DIN, British BSI, France NF), Japanese JIS and Chinese GB standard (for reference).
| AISI 303 stainless steel equivalent material | |||||||||||||||||
| US | European Union | ISO | Japan | China | Australia | India | Rusia | Korea | |||||||||
| Standard | AISI Type (UNS) | Standard | Grade (Steel Number) | Standard | ISO Name (ISO Number) | Standard | Grade | Standard | Grade | Standard | Grade | Standard | Grade | Standard | Grade | Standard | Grade |
| AISI SAE; ASTM | 303 (UNS S30300) | EN 10088-2; EN 10088-3 | X8CrNiS18-9 (1.4305) | ISO 15510 | X10CrNiS18-9 (4305-303-00-I) | JIS G4303; JIS G4304; JIS G4309; | SUS303 | GB/T 20878; GB/T 4237; GB/T 3280 | Y1Cr18Ni9; Y12Cr18Ni9 (New designation) | ||||||||
