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Type 303 is "18-8" chromium-nickel stainless steel modified by the addition of selenium or sulphur, as well as phosphorus, to improve machinability and non- seizing properties. It is the most readily machinable of all the chromium-nickel arades and has good corrosion resistance It is non-magnetic in the annealed condition and not hardenable by heat treatment. Tensile strength and hardness can be increased by cold working. It is manufactured by the electric-furnace process and meets the exacting requirements of the aircraft industry.

UNS S30300. S30323

Color Marking

Type 303Se
Annealed Bars: Ends painted Purple
High Tensile Bars (Condition B): Ends painted Brown

Physical Condition A

Stock Lengths 10' to 12' and 20' to 22'

Max. Brinell 207
Unit of Measure

Specifications

Estimated Weight per Foot

 N/A 30.45 lb

Estimated Weight 12-Ft. Bar

 N/A 365.3 lb

Analysis

N/A 303Se
Carbon .15 Max.
Manganese 2.00 Max.
Phosphorus .17 Max.
Sulphur .04 Max.
Se. .15/.40
Si. 1.00 Max.
Cr.17.00/19.00
Ni. 8.00/10.00
Mo. .75 Max.
Cu. .75 Max.

Specifications

N/A The following specifications are generally applicable:
AMS 5640, ASTM A 314, ASTM A 320, ASTM A 582

Applications

N/A Used almost exclusively for parts requiring machining, grinding, or polishing where good corrosion resistance is also required. Its non-seizing and non-galling properties make it ideal for moving parts. Being an austenitic steel, it is useful where low magnetic permeability is desired.

Corrosion Resistance

N/A Because of the elements which are added to improve machinability, Type 303 has slightly less general corrosion resistance than the regular chromium-nickel grades such as Type 302. Maximum corrosion resistance is obtained in the annealed condition.

Resistance to Scaling

N/A This grade has excellent scale resistance at temperatures up to 1600°F in continuous service. Like other chromium-nickel grades, it has a high coefficient of expansion which should be considered in designing.

Mechanical Properties

N/A Cond. A (Annealed)
1/2" and under
Tensile Strength - 125.000 psi Max.
Brinell Hardness 140/255
over 1/2"
Brinell Hardness 140/255

Cond. B (High Tensile)
up to 3/4"
Tensile Strength - 125.00 psi Min.
Yield Strength - 100,000 psi Min.
Elongation in 2" - 12% Min.
Reduction of Area 35% Min.
Brinell Hardness 321 Max.
Over 3/4" to 1"
Tensile Strength - 115.00 psi Min.
Yield Strength - 80,000 psi Min.
Elongation in 2" - 15% Min.
Reduction of Area 35% Min.
Brinell Hardness 321 Max.
Over 1" to 1 1/4"
Tensile Strength - 105.00 psi Min.
Yield Strength - 65,000 psi Min.
Elongation in 2" - 20% Min.
Reduction of Area 35% Min.
Brinell Hardness 321 Max.
Over 1 1/4" to 1 1/2"
Tensile Strength - 100.00 psi Min.
Yield Strength - 50,000 psi Min.
Elongation in 2" - 28% Min.
Reduction of Area 45% Min.
Brinell Hardness 321 Max.
Over 1 1/2" to 3"
Tensile Strength - 95.00 psi Min.
Yield Strength - 45,000 psi Min.
Elongation in 2" - 28% Min.
Reduction of Area 45% Min.
Brinell Hardness 321 Max.

In practice, annealed bars will average as follows:
H.R. Ann
Tensile Strength - 90.00 psi
Yield Strength - 35,000 psi
Elongation in 2" - 50% Min.
Reduction of Area 55% Min.
Izod Impact Ft. Lbs.80%
Brinell Hardness 160 Max.

Ann. & C. F
Tensile Strength - 100.00 psi
Yield Strength - 60,000 psi
Elongation in 2" - 40% Min.
Reduction of Area 53% Min.
IBrinell Hardness 228 Max.

Machinability

N/A Type 303 has considerably better machining characteristics than the other chromium-nickel grades. It has machinability rating of approximately 78% with 1212 rated 100%. Surface cutting speed on automatic screw machines is approximately 130 feet per minute.

Weldability

N/A This grade has only fair welding properties.

Forming

N/A This'grade has fairly good forming properties.

Forging

N/A Forge between 2100° and 2350°F. Do not forge below 1700°F

Annealing

N/A Annealing range is between 1850° and 2050°F. Cool rapidly. Water should be used for heavier sections; air for lighter sections. The stress relieving range is between 400° and 750 °F.