303 Stainless Steel
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EN 1.4305 grade 303 Stainless Steel provides the best machinability among all the austenitic Stainless Steels.
303 gains its improved machining and galling characteristics by the addition on sulphur, however this addition also lowers the stainless steels corrosive resistance and reduces its toughness slightly when comparing it to 304 Stainless Steel.
Corrosion and Oxidisation Resistance of 303
303 Stainless Steel shows good corrosion and oxidisation resistance in mildly corrosive atmospheric environments. Its sulphide inclusions act as pit initiation sites meaning it provides a lot less resistance than 304.
Grade 303 should not be exposed to marine or other similar environments, to prevent rapid pitting corrosion.
EN 1.4305 303 Stainless Steel provides good oxidisation resistance in intermittent service to 760°C (1400°F) and continuous service to 870°C (1,598°F)
The use of 303 stainless steel is not recommended in the range of 425-860°C (797-1580°F) due to carbide precipitation.
303 is susceptible to sensitisation.
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Chemical Composition of 303
|
° |
C |
Mn |
Si |
P |
S |
Cr |
Mo |
Ni |
N |
|
Min |
 |
 |
 |
 |
 |
17.0 |
 |
8.0 |
 |
|
Max |
0.15 |
2.0 |
1.0 |
0.20 |
0.15 |
19.0 |
 |
10.0 |
 |
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Welding
Welding of 303 Stainless is not recommended however if this is if unavoidable then use 308L or 309 for electrodes. 303 must be annealed for optimal corrosion protection.
For optimal annealing heat to 1010-1120°C (1850-2048°F) and cool rapidly with air or water.
EN 1.4305 303 stainless steel cannot be hardened by thermal treatment.°
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Mechanical Properties of 303
|
Yield Strength 0.2% (MPa) min |
Tensile strength (MPa) min |
Elongation (% in 50mm) min |
Rockwell B (HR B) max |
Brinell (HB) max |
|
450 - 650 |
750 - 800 |
34 |
95 |
262 |
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Physical Properties of 303
|
Density (kg/ m cube) |
Elastic Modulus (GPa) |
Specific heat 0-100°C (J/kg.K) |
Electrical resistivity (nΩ.m) |
|
7900 |
193 |
500 |
720 |
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Mean Coefficient of Thermal Expansion (μ/m/°C)
|
0-100°C |
0-315°C |
0-538°C |
|
17.3 |
17.8 |
18.4 |
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Thermal Conductivity (W/m.K)
|
at 100°C |
at 500°C |
|
16.3 |
21.5 |
