AISI 303 stainless steel (UNS S30300, SS 303)
AISI 303 stainless steel (UNS S30300) was developed to facilitate cutting and basically belongs to 18-8 stainless steel. Improves cutting performance while maintaining good mechanical properties. SS 303 material has higher sulfur content, which reduces the strength of the cutting tool, but has a negative impact on corrosion resistance, so the corrosion resistance is not as good as AISI 304 stainless steel.
Properties of Type 303 Stainless Steel
The following data sheet provides properties of 303 stainless steel, including chemical composition, physical and mechanical properties, heat treatment, welding, etc.
Chemical composition
The chemical composition of SS 303 material is listed in the following table based on casting analysis.
| Chemical composition, % | |||||||||
| ASTM | AISI (UNS) | C, ≤ | Yes, ≤ | Mn, ≤ | P, ≤ | S, ≥ | Cr | No | Grades |
| 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 wires and wire rods | ||||||||
| ASTM A895 | Free machining plate, plate and strip | ||||||||
| ASTM A959 | Forged Stainless Steels | ||||||||
| ASTM A473 | Stainless steel forgings | ||||||||
| ASTM A314 | Billets and bars for forging | ||||||||
Grades:
- ASTM A582/A582M : Standard Specification for Free-Machining Stainless Steel Bars
- ASTM A581/A581M : Standard Specification for Free-Machining Stainless Steel Wire and Wire Rod
- ASTM A895 : Standard Specification for Free-Machining Stainless Steel Sheets, Plates, and Strips
- ASTM A959 : Standard Guide for Specification of 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
The physical properties of AISI 303 stainless steel are given in the following lists, including density, thermal expansion, modulus of elasticity, thermal conductivity, specific heat capacity and electrical resistance.
Grades:
- 10 -6 ·K -1 = 10 -6 /K
- 1Ω mm²/m = 1 μΩ m
- 1 g/cm3 = 1 kg/dm3 = 1000 kg/m3
- 1 GPa = 1kN/mm2
- 1 MPa = 1 N/mm2
| Physical properties | |
| Density of 303 stainless steel, 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°C |
| Electrical resistivity, μΩ·m | 0.72 at 20°C |
| Magnetic permeability | 1.02 (approximate) |
| Elastic modulus, GPa (10 6 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 not magnetic in the annealed condition, but may become slightly magnetic due to cold working.
Mechanical properties
The mechanical properties of 303 steel 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 by 50 mm (2 in.), %, ≥ | Area Reduction, %, ≥ |
| ASTM A473 | 303 (UNS S30300) | Annealed | 515 (75) | 205 (30) | 40 | 50 |
| ASTM A581/A581M | Annealed | 585-860 (85-125) | ||||
| Cold work | 795-1000 (115-145) | |||||
Brinell hardness:
- 160, annealed bar
- 228, cold drawn
Heat treatment
Recommended annealing temperatures for AISI 303 forged stainless steel are 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)
Longer tool life achieved with coated cutting tools
| snipping tool | Coating | Part material | Machined parts before regrinding | ||
| Type | High speed tool steel, type AISI | Uncoated | Coated | ||
| Brooch insertion | M3 | Tin | Type 303 stainless steel | 100,000 | 300,000 |
| Form Tool | T15 | Tin | 1,840 | 5,890 | |
Recommended face angles along with setback angles for type 303 stainless steel:
- Facial angle, 15 degrees;
- Recoil angle: 0.5 – 2 degrees.
The speed and feed ranges for shovel drilling are listed in the following table.
| Perforated material | Drill diameter, mm (in.) | |||||||||
| 25 (1) | 50 (2) | 75 (3) | 100 (4) | 125 (5) | ||||||
| Speed, rotation/min | Feed rate, mm/rev (in/rev) | Speed, rotation/min | Feed rate, mm/rev (in/rev) | Speed, rotation/min | Feed rate, mm/rev (in/rev) | Speed, rotation/min | Feed rate, mm/rev (in/rev) | Speed, rotation/min | Feed rate, mm/rev (in/rev) | |
| Type 303 and 303 If | 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 | To feed | Insert style | Note | |||||
| Standard length | Sketch length | |||||||||
| mm | in. | m/min | sfm | m/min | sfm | mm/rotation | in./rev | |||
| AISI 303, 304 and 316, 416 | 19-30 | 0.75 – 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, coated with titanium. | |||||
| 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 | ||||||
Rated speeds and feeds for thread milling with high-speed steel tools
| Work material | Hardness, HB | Speed | To 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 cutting and creasing screw threads
| Working metal | Speed for pitch | |||||||
| ≤ 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 |
Rated speed, cutting rate and belt life for cutting steel bars
| Steel being cut | Hardness, HB | Band speed | Cut-off rates | Band life in terms of total area cut | |||
| m/min | sfm | mm2 x 10 3 /min | in.2/min | mm2 × 10 6 | in.2 × 10 3 | ||
| SS 303, 303F | 150-200 | 40-27 | 130-90 | 3.2-1.3 | 5-2 | 2.1 | 3.3 |
Use and application
SS303 material is mainly used for parts that need machining, grinding or polishing, suitable for fast cutting to make rollers, shafts, screws, nuts, etc.
Equivalent Material
The equivalent materials for SS 303 stainless steel are listed in the data sheet below, including European standards (German DIN, British BSI, French NF), Japanese JIS and Chinese GB (for reference).
| AISI 303 stainless steel equivalent material | |||||||||||||||||
| USA | European Union | ISO | Japan | China | Australia | India | Russia | Korea | |||||||||
| Standard | AISI type (UNS) | Standard | Class (Steel Number) | Standard | ISO name (ISO number) | Standard | Note | Standard | Note | Standard | Note | Standard | Note | Standard | Note | Standard | Note |
| 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) | ||||||||
