Products Description
Alloy 303 (UNS S30300) is an austenitic stainless steel specifically designed for applications that involve extensive machining operations. Here are some key points about Alloy 303:Alloy 303 is highly regarded for its excellent machinability. It has a sulfur addition that helps in breaking up turnings and reducing drag on the cutting tool, resulting in improved machining characteristics compared to conventional 18-8 stainless steels.Alloy 303 is nonmagnetic in the annealed condition. However, it may become slightly magnetic as a result of cold working or other processing steps.The addition of sulfur in Alloy 303 has a negative impact on its corrosion resistance. It is generally less resistant to mildly corrosive environments compared to Alloy 304 (another commonly used stainless steel grade). Therefore, Alloy 303 may be more susceptible to corrosion in certain conditions.
Applications
- Aerospace Parts
Fittings
Pump and Valve Components
Screw Machine Products
Standards
ASTM........A 895Corrosion Resistance
Alloy 303 is generally resistant to mildly corrosive environments, but its corrosion resistance is inferior to Alloy 304 in most applications. Here are some additional points regarding its corrosion resistance:Comparison to other grades: Alloy 303 has better corrosion resistance compared to free-machining grade 416. However, it may have somewhat inferior corrosion resistance compared to other 400 series stainless steels that do not contain higher sulfur levels.Sulfur content and corrosion resistance: The higher sulfur content in Alloy 303 can have a negative impact on its corrosion resistance. Sulfur can promote the formation of sulfides, which can reduce the alloy's resistance to corrosion.Chemical treatment for optimal corrosion resistance: To achieve optimal corrosion resistance with Alloy 303, it is recommended to subject the alloy to chemical treatment to remove sulfides from the final surfaces. This treatment can help improve the corrosion resistance of the alloy.
Chemical Analysis
Weight % (all values are maximum unless a range is otherwise indicated)
|
|
|
|
|
|
Chromium |
17.0 min.-19.0 max. |
Sulfer |
0.15-0.35 |
|
Nickel |
8.0 min.-10.0 max. |
Silicon |
1.00 |
|
Carbon |
0.10 |
Copper |
1.00 |
|
Manganese |
2.00 |
Nickel |
0.110 |
|
Phosphorus |
0.20 |
Iron |
Balance |
Physical Properties
Density
0.285 lbs/in37.89 g/cm3
Specific Heat
0.12 BTU/lb-°F (32 – 212°F)502 J/kg-°K (0 – 100°C)
Modulus of Elasticity
28.0 x 106 psi193 GPa
Thermal Conductivity 212°F (100°C)
112 BTU/hr/ft2/ft/°F16.2 W/m-°K
Melting Range
2500 – 2590°F1480 – 1530°C
Electrical Resistivity
28.3 Microhm-in at 68°C72.0 Microhm-cm at 20°C
Mechanical Properties
Typical Values at 68°F (20°C)
|
Yield Strength 0.2% Offset |
Ultimate Tensile Strength |
Elongation in 2 in. |
Hardness |
||
|
psi (min.) |
(MPa) |
psi (min.) |
(MPa) |
% (min.) |
(max.) |
|
45,000 |
310 |
85,000 |
586 |
50 |
202 (HBN) |
Fabrication Data
Heat Treatment
Annealing – Heat to a minimum temperature of 1900°F (1038°C) and water quench or rapid cool by other means.
Hardening – Alloy 303 cannot be hardened by thermal treatment, it can only be hardened by cold working.
Cold Forming
The cold formability of Alloy 303 is adversely impacted by the high sulfur content. The alloy may be bent with a generous bend radius, however, when cold forming is required, 304 should be utilized.
Hot Forming
The high sulfur content of Alloy 303 also has a detrimental impact on hot workability. If hot forming is required, once again, 304 should be considered as an alternate selection.
Machining
Alloy 303 was developed specifically for ease of machining. The sulfur addition assists in breaking up turnings which reduces drag on the cutting tool. It produces small brittle chips and may be machined at high speeds with deep cuts and heavy feeds.
The table below suggests speeds and feeds for various machining operations for 303.
|
Machinability |
High Speed Tooling |
Carbide Tooling |
Depth, Width or Diameter of Tool |
||
|
|
Speed (sfm) |
Feed (in./rev.) |
Speed (sfm) |
Feed (in./rev.) |
(in.) (dia./in.) |
|
Turning |
115 135 |
0.0150 0.0050 |
375 600 |
0.025 0.007 |
0.005-0.200 0.002-0.004 |
|
Cut-off |
90 100 |
0.0015 0.0025 |
275 325 |
0.002 0.004 |
1/16 1/4 |
|
Forming |
100 100 |
0.0020 0.0015 |
375 350 |
0.003 0.002 |
1 2 |
|
Drilling |
70 85 100 |
0.0060 0.0100 0.0200 |
— 700 800 |
— 0.005 0.007 |
1/4 1/2 1-2 |
|
Reaming |
90 90 |
0.0050 0.0150 |
— — |
— — |
1/4 1-2 |
|
End Milling |
130 130 |
0.0030 0.0060 |
300 350 |
0.004 0.009 |
1/2 1-2 |
|
Tapping and Threading |
10 40 |
— — |
— — |
— — |
7 threads/in. 25 theads/in. |
Welding
Alloy 304/304H can be readily welded by most standard processes. After welding Alloy 304/304H it may be necessary to anneal the plate to restore the corrosion resistance lost by sensitization to intergranular corrosion when chromium carbides precipitate in the grain boundaries in the weld heat-affected zone.