AISI 303 Stainless Steel Properties, SS 303 Density, Hardness, Magnetic, Equivalent (UNS S30300)

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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 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.

Datasheet & Specification

The following tables and lists give the stainless steel 303 datasheet and specification including chemical composition, physical properties 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

Type 303 Stainless Steel Properties

The tables below list 303 stainless steel properties, including physical and mechanical properties.

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 (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 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 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 is mainly used for parts that need machining, grinding or polishing, suitable for rapid cutting to make rolls, shafts, bolts, nuts, etc.

Equivalent

SS 303 stainless steel equivalent to 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)

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