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, %
ASTMAISI (UNS)C, ≤Si, ≤Mn, ≤P, ≤S, ≥CrNiNotes
ASTM A582/A582M303 (UNS S30300) Stainless Steel Bars
ASTM A581/A581MFree-Machining Stainless Steel Wire and Wire Rods
ASTM A895Free-Machining Plate, Sheet, and Strip
ASTM A959Wrought Stainless Steels
ASTM A473Stainless Steel Forgings
ASTM A314Billets and bars for forging


  • 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.


  • 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·m0.72 at 20℃
Magnetic permeability1.02 (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
ASTMAISIConditionsTensile Strength, MPa (ksi), ≥0.2% Yield Strength, MPa (ksi), ≥Elongation in 50 mm (2 in.), %, ≥Reduction of Area, %, ≥
ASTM A473303 (UNS S30300)Annealed515 (75)205 (30)4050
ASTM A581/A581MAnnealed585-860 (85-125)
Cold Worked795-1000 (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.


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 toolCoatingWorkpiece materialWorkpieces machined before resharpening
TypeHigh-speed tool steel, AISI typeUncoatedCoated
Broach insertM3TiNType 303 stainless steel100,000300,000
Form toolT15TiN1,8405,890

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 drilledDrill diameter, mm (in.)
25 (1)50 (2)75 (3)100 (4)125 (5)
Speed, rev/minFeed rate, mm/rev (in./rev)Speed, rev/minFeed rate, mm/rev (in./rev)Speed, rev/minFeed rate, mm/rev (in./rev)Speed, rev/minFeed rate, mm/rev (in./rev)Speed, rev/minFeed rate, mm/rev (in./rev)
Type 303 and 303 Se225-2750.15-0.25 (0.006-0.010)120-1250.25-0.38 (0.010-0.015)75-900.38-0.51 (0.015-0.020)55-650.51-0.63 (0.020-0.025)45-550.63-0.76 (0.025-0.030)

Recommended cutting parameters for indexable drills with uncoated and titanium-coated carbide inserts

MaterialDrill sizeSpeedFeedInsert styleGrade
Standard lengthStub length
AISI 303, 304 and 316, 41619-30.75 – 1.187545-105150-35045-150150-5000.08-0.100.003-0.004SPGMC-2, Uncoated
32-36.51.25-1.43750.10-0.130.004-0.005SNMGC-5, Titanium coated.

Nominal speeds and feeds for thread milling with high-speed steel tools

Work materialHardness, HBSpeedFeed
Type 303135-185301000.050.002

Nominal speeds for die cutting of screw threads

Work metalSpeed for pitch of
≤ 78-1516-24≥ 25
Types 303, 410, 420F, 440F3104.5156207.525

Nominal speed, cutting rate, and band life for the cutoff band sawing of steel bars

Steel being cutHardness, HBBand speedCutting ratesBand life in terms of total area cut
m/minsfmmm2 x 103/minin.2/minmm2 × 106in.2 × 103
SS 303, 303F150-20040-27130-903.2-1.35-22.13.3

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.


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
USEuropean UnionISOJapanChinaAustraliaIndiaRusiaKorea
StandardAISI Type (UNS)StandardGrade (Steel Number)StandardISO Name (ISO Number)StandardGradeStandardGradeStandardGradeStandardGradeStandardGradeStandardGrade
303 (UNS S30300)EN 10088-2; EN 10088-3X8CrNiS18-9 (1.4305)ISO 15510X10CrNiS18-9 (4305-303-00-I)JIS G4303;
JIS G4304;
JIS G4309;
SUS303GB/T 20878;
GB/T 4237;
GB/T 3280
Y1Cr18Ni9; Y12Cr18Ni9 (New designation)

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