Stainless Steel Plate

Sandmeyer Steel offers Alloy 303 in thicknesses from 3/16" (4.8mm) through 2” (50.8mm).

Available thicknesses for Alloy 303:

3/16" 1/4" 3/8" 7/16" 1/2" 9/16"
4.8mm 6.3mm 9.5mm 11.1mm 12.7mm 14.3mm
 
5/8" 3/4" 7/8" 1" 1 1/8" 1 1/4"
15.9mm 19mm 22.2mm 25.4mm 28.6mm 31.8mm

Alloy 303 (UNS S30300) is a non-magnetic, austenitic, free-machining stainless steel that is a modification of the basic 10% chromium -8% nickel stainless steel specially designed to exhibit improved machinability while maintaining good mechanical and corrosion-resistant properties.

General Properties

Alloy 303 (UNS S30300) is an austenitic stainless steel developed for applications requiring extensive machining operations. The alloy has a sulfur addition which assists in breaking up turnings while reducing drag on the cutting tool when compared to the machining characteristics of the conventional 18-8 stainless steels.

The alloy is nonmagnetic in the annealed condition , but may become slightly magnetic as a result of cold working. The addition of sulfur negatively impacts the corrosion resistance of 303 making it less resistant than 304 to mildly corrosive environments.


Applications

  • Aerospace Parts
  • Fittings
  • Pump and Valve Components
  • Screw Machine Products

Standards

ASTM........A 895

Corrosion Resistance

Alloy 303 is resistant to mildly corrosive environments. However, the alloy’s corrosion resistance is inferior to 304 in most applications. Its corrosion resistance is superior to 416, another free-machining grade, but is somewhat inferior to other 400 series stainless steels which do not contain higher sulfur levels. In order to obtain optimal corrosion resistance, it is recommended that Alloy 303 be chemically treated to remove sulfides from the final surfaces.

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/in3
7.89 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 psi
193 GPa

 

Thermal Conductivity 212°F (100°C)

112 BTU/hr/ft2/ft/°F
16.2 W/m-°K

Melting Range

2500 – 2590°F
1480 – 1530°C

Electrical Resistivity

28.3 Microhm-in at 68°C
72.0 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 303 is not recommended for applications requiring welding. If it is necessary to weld the alloy, AWS E312 filler metal may be considered.

NOTE: The information and data in this product data sheet are accurate to the best of our knowledge and belief, but are intended for informational purposes only, and may be revised at any time without notice. Applications suggested for the materials are described only to help readers make their own evaluations and decisions, and are neither guarantees nor to be construed as express or implied warranties of suitability for these or other applications.

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