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303 stainless steel plates

303 stainless steel plates

303 is austenitic free-machining stainless steel which is used primarily for parts requiring machining, grinding or polishing. This alloy offers good corrosion resistance in mild environments and good forming properties. It is non-magnetic in the annealed condition and can only be hardened by cold working.

Standard Inventory Specifications

  • UNS S30300
  • AMS 5640 Chem Only
  • ASTM A 895

Common Trade Names

  • AISI 304
  • ASTM/ASME ……………. UNS S30300
  • EURONORM ……………. FeMi35Cr20Cu4Mo2
  • DIN ………………………… 2.4660

Improve performance in rugged environments with 303 stainless steel plate from Sunny Steel. A non-magnetic, austenitic stainless steel that is not hardenable by heat treatment, 303 stainless steel plate offers good weather resistance, toughness and forming properties. Comprised of chromium, nickel, stainless steel and other alloys, this material type is designed to exhibit improved machinability while maintaining strong mechanical and anti-corrosion properties.

303 stainless steel plate is typically chosen for applications that require heavily machined parts. Examples include:

  • Architectural accents
  • Machined parts
  • Nozzles
  • Aircraft components
  • Nuts and bolts
  • Electrical components
  • Gears
  • Pump parts
  • Shafts
  • Valve components
  • Bushings
  • Industrial parts

General Properties

Alloy 303 is a non-magnetic, austenitic stainless steel that is not hardenable by heat treatment. It is the free machining modification of the basic 18% chromium / 8% nickel stainless steel. Alloy 303 was specially designed to exhibit improved machinability while maintaining good mechanical and corrosion resistant properties Due to the presence of sulfur in the steel composition, Alloy 303 is the most readily machineable austenitic stainless steel; however, the sulfur addition does lower Alloy 303’s corrosion resistance to below that of Alloy 304. Like other austenitic grades, Alloy 303 demonstrates excellent toughness, although the sulfur does reduce this a little as well.

Corrosion Resistance

  • Good resistance to mildly corrosive atmospheres, but significantly less than Alloy 304
  • When additional sulfur is added to improve machinability, it can often slightly reduce corrosion resistance
  • In most dry and mild corrosive environments, Alloy 303 is comparable to other unmodified alloys
  • Should not be exposed to moist, marine environments as it is subject to rapid-pitting corrosion and a rust film will tend to form
  • Like other common austenitic stainless steels, it is subject to corrosion cracking in chloride environments above 60oC

Heat Resistance

  • Good oxidation resistance at temperatures up to 1700oF (927 oC)
  • Continuous use at temperatures above 1400oF (760oC) is not usually recommended due to carbide precipitation which can lead to irregular scaling
  • Does not have a low carbon content so it is also vulnerable to sensitisation


Chemical Properties:

% Cr Ni C Si Mn P S Mo Fe
303 min: 17.0
min: 8.0
max: 10.0
0.75 balance

Mechanical Properties:

Grade Tensile Strength
ksi (min.)
Yield Strength 0.2%
Offset ksi (min.)
Elongation –
% in
50 mm (min.)
(Brinell) MAX
(Rockwell B) MAX
303 75 30 35 228

Physical Properties:

Coefficient of
Thermal Expansion (min/in)-°F
Electrical Resistivity mW-in Thermal Conductivity BTU/hr-ft-°F Melting
at 68 °F at 68 – 212°F at 68 – 932°F at 68 – 1450°F at 68°F at 212°F at 392°F at 752°F at 1112°F at 1472°F at 68 – 212°F
0.29 9.2 10.4 10.9 28.3 30.7 33.8 39.4 43.7 47.6 113.2 2552°F

303 Stainless Steel

303 Stainless Steel is an “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 stainless grades and has good corrosion resistance, although less than other chromium-nickel grades (304/316). It is non-magnetic in the annealed condition and not hardenable by heat treatment.

Stainless Steel 303 1.4305

Stainless steel type 1.4305 is popularly known as grade 303 stainless steel. Grade 303 is the most readily machineable of all the austenitic grades of stainless steel.

Stainless Steel 303 1.4305
Stainless steel type 1.4305 is popularly known as grade 303 stainless steel. Grade 303 is the most readily machinable of all the austenitic grades of stainless steel. The machinable nature of grade 303 is due to the presence of Sulphur in the steel composition. Whilst the Sulphur improves machining, it also causes a decrease in the corrosion resistance and a slight lowering of the toughness. The corrosion resistance of type 303 is lower than that for 304. The toughness is still excellent as with other austenitic grades. It is reasonable to expect specifications in this data sheet to be similar but not necessarily identical to those given in this data sheet.


  • Shafts
  • Springs
  • Nuts & bolts
  • Gears
  • Aircraft fittings
  • Bushings
  • Supplied Forms
  • Bar

Alloy Designations
Stainless steel grade 1.4305/303 also corresponds to: UNS S30300, BS 303S31 and EN 58M.

Corrosion Resistance
Sulphur additions to the composition act as initiation sites for pitting corrosion. This decreases the corrosion resistance of 303 stainless steel to less than that for 304. However, corrosion resistance remains good in mild environments. In chloride containing environments over 60°C, 303 stainless steel is subject to pitting and crevice corrosion. Grade 303 stainless is not suitable for use in marine environments.

Heat Resistance
303 stainless steel has good resistance to oxidation when intermittently exposed to temperatures up to 760°C. It also has good oxidation resistance in continuous service to 870°C. This however, is not recommended as 303 is sensitive to carbide precipitation with continuous use at 425-860°C.

Fabrication of all stainless steels should be done only with tools dedicated to stainless steel materials. Tooling and work surfaces must be thoroughly cleaned before use. These precautions are necessary to avoid cross contamination of stainless steel by easily corroded metals that may discolour the surface of the fabricated product.

Cold Working
303 is not readily cold workable. Some cold working is possible but sharp bending should not be attempted.

Hot Working
Fabrication methods like forging, that involve hot working should occur after uniform heating to 1149-1260°C. The fabricated components should then be rapidly cooled to ensure maximum corrosion resistance.

303 stainless steel has excellent machinability. Machining can be enhanced by adhering to the following rules: Cutting edges must be kept sharp. Dull edges cause excess work hardening. Cuts should be light but deep enough to prevent work hardening by riding on the surface of the metal. Chip breakers should be employed to assist in ensuring swarf remains clear of the work. Low thermal conductivity of austenitic alloys results in heat concentrating at the cutting edges. This means coolants and lubricants are necessary and must be used in large quantities.

Heat Treatment
303 stainless steel cannot be hardened by heat treatment. Solution treatment or annealing can be done by rapid cooling after heating to 1010- 1120°C.

The sulphur addition present in 303 stainless steel results in poor weldability. If 303 must be welded the recommended filler rods or electrodes are grades 308L and 309 stainless steels. For maximum corrosion resistance, the welds must be annealed.

Chemical Compositionsa)

Element % Present
Carbon (C) 0.10
Chromium (Cr) 17.00 – 19.00
Manganese (Mn) 2.00
Silicon (Si) 1.00
Phosphorous (P) 0.045
Sulphur (S) 0.015 – 0.35
Nickel (Ni) 8.00 – 10.00
Nitrogen (N) 0.10
Copper (Cu) 1.00
Iron (Fe) Balance

Mechanical properties

Property Value
Comprehensive Strength 190 MPa
Tensile Strength 500 – 700 MPa
Elongation 35 Min%

Physical Properties

Property Value
Density 8.03 Kg/m3
Melting Point 1455 °C
Thermal Expansion 17.2 x 10-6 /K
Modulus of Elasticity 193 GPa
Thermal Conductivity 16.3W/m.K
Electrical Resistivity 0.072 x 10-6 Ω .m

Sunny Steel provide a wide range of steel products as Steel pipes, Seamless tube and seamless pipes, Alloy pipes, Pipe fittings, Composite steel pipe used in the industry, construction etc.



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