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303 Stainless Steel

303 stainless steel, or Type 303 is a non-magnetic, austenitic stainless steel that is not hardenable by heat treatment. It is a free machining modification of the basic 18% chromium / 8% nickel stainless steel. This means that it has been modified to make it easier to machine and shape through processes such as drilling, turning, and milling. 

303 stainless steel

303 stainless steel
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303 Stainless Steel is an austenitic grade of stainless steel that is known for its exceptional machinability.

This makes it the ideal choice for applications that require parts to be heavily machined, such as gears, shafts, aircraft fittings, and other small parts.

Additionally, it provides good mechanical properties and corrosion resistance, making it suitable for use in a wide range of industries, including aerospace, automotive, and medical.

Due to its exceptional machinability, 303 Stainless Steel is often used as a replacement for other grades of stainless steel, such as 304, when cost and lead time are a concern.

It can be easily machined with conventional tools, and does not require any special cutting fluids or coatings, making it a cost-effective option for manufacturers.

Type 303 Stainless Steel is also known for its excellent toughness, making it resistant to cracking and breaking. It is also a non-magnetic grade of stainless steel, which is important in applications where magnetic properties are not desired.

If you are looking for the best prices for Type 303 Stainless Steel, please contact us. We can provide you with competitive pricing and quick delivery times.

303 Stainless Steel Properties and Specifications

303 stainless steel owes its machineable nature to the presence of Sulphur in the composition. However, it should be noted that the Sulphur also decreases the corrosion resistance of the steel and slightly lowers its toughness.

The toughness is still excellent as with other austenitic grades. AISI 304 stainless steel offers higher corrosion resistance than 303.

303 stainless steel is known for its exceptional machinability, which is attributed to the presence of Sulphur in its composition. Sulphur is added to the steel in small amounts as a strengthening agent and to improve its machinability.

This makes it easier to machine and shape through processes such as drilling, turning, and milling.

However, it is important to note that the addition of Sulphur also decreases the corrosion resistance of the steel and slightly lowers its toughness. While the toughness of 303 stainless steel is still excellent when compared to other grades of steel, it is not as high as other austenitic grades like AISI 304.

 

  • Austenitic Stainless Steel
  • Excellent machining characteristics
  • Free machining version of Types 302 and 304 is used for parts requiring extensive machining
  • Annealed condition is non-magnetic
  • Type 303 is slightly magnetic when cold worked
  • Good corrosion resistance
  • Good oxidation resistance up to 1700 degrees F

303 stainless steel is covered by the following specifications:

  • AMS 564OG
  • ASTM A314-63
  • ASTM A320-65
  • ASTM 581-67
  • ASTM 582-67
  • QQ-S-764A
  • MIL-S-862B
  • Anneal: Heat to 1900 – 2050 F and water quench.
  • Harden: Type 303 cannot be hardened by heat treatment.
  • Type 303 should be heated slowly to 2000-2150 F.
  • Soaked for a sufficient time, then raised to 2200 – 3250 F.
  • Should not be forged below 1700 F.
  • Excellent corrosion resistance.
  • Effectively resist attack in atmospheric exposures, sterilizing solutions, most organic and many inorganic chemicals, most dyes nitric acid and foods.
  • For best corrosion resistance finished parts should be free from scale and foreign particles.
  • Only fair weldability.
  • Can be welded using proper procedures.
  • Weldability can be improved by using methods that minimize dilution of the weld metal with the melted base metal.
  • Reducing the time that welds are in the hot-short temperature range and use of Type 312 (29-9) filler metal helps obtain satisfactory results.

What is 303 Stainless Steel?

303 stainless steel is a type of non-magnetic, austenitic stainless steel. It is an alloy that contains 18% chromium and 8% nickel, and is often referred to as 18-8 stainless steel.

The “303” designation refers to the addition of small amounts of sulfur to the steel, which improves its machinability. This makes it easy to machine and shape through processes such as drilling, turning and milling. Despite the sulfur addition, it still offers good corrosion resistance and excellent toughness.

It is commonly used in applications that require high corrosion resistance and ease of machining, such as in the production of gears, screws and other small parts, aerospace, automotive, and medical, marine and coastal applications, petrochemical industry and electronics.

History of 303 Stainless Steel

303 stainless steel was developed in the 1920s by the American Iron and Steel Institute (AISI) as a free-machining alternative to the basic 18% chromium / 8% nickel stainless steel.

The “303” designation refers to the addition of small amounts of sulfur to the steel, which improves its machinability. It was intended to be used for high speed automatic machining operations, and was a popular choice for the production of gears, screws, and other small parts. Due to its excellent machinability, it quickly became a popular choice in the manufacturing industry, and was used in a variety of applications, including in aerospace, automotive, and medical industries.

Its corrosion resistance and toughness properties make it suitable for marine and coastal applications, petrochemical industry and electronics.

Uses for 303 Stainless Steel

303 stainless steel is a versatile and widely-used type of stainless steel that offers excellent machinability and good mechanical properties. Due to its unique properties, it is used in a variety of applications in various industries.

Below are some of the most common uses of 303 stainless steel:

Machining and Manufacturing

303 stainless steel is best known for its exceptional machinability, making it a very popular choice for parts that require heavy machining.

This includes gears, shafts, aircraft fittings, and other small parts. Its easy machining capabilities make it a cost-effective option for manufacturers and it does not require any special cutting fluids or coatings.

Automotive and Aerospace

303 stainless steel is often used in the automotive and aerospace industries due to its toughness and corrosion resistance properties.

It is used in a variety of applications, such as in the production of gears and shafts for aircraft engines, as well as in the manufacture of automotive parts such as nuts, bolts and screws.

Medical and Food Processing

Type 303 is a popular choice in the medical and food processing industries due to its excellent corrosion resistance and easy machinability.

It is often used in the production of medical equipment, such as surgical instruments and needles, as well as in the manufacture of food processing equipment, such as cutting blades and conveyor belts.

Marine/Coastal Applications

303 stainless steel is a corrosion-resistant material, making it suitable for marine and coastal applications. Its non-magnetic properties make it a good choice for applications where magnetic properties are not desired, such as in the production of boating equipment and marine hardware.

Its strength and durability make it suitable for use in coastal construction projects, such as in the construction of seawalls and other coastal infrastructure.

Petrochemical Industry

303 stainless steel is also commonly used in the petrochemical industry due to its excellent corrosion resistance properties. It is often used in the production of equipment for the oil and gas industry, such as valves and fittings, as well as in the production of heat exchangers and other process equipment.

The strength and durability of 303 stainless steel make it suitable for use in harsh environments where corrosion resistance is a concern.

Electronics Industries

Type 303 steel is also used in the electronics industry due to its excellent machinability properties. 303 stainless steel is used in the production of electronic components: connectors, switches, and other small parts. Its properties make it suitable for electronic devices that may be exposed to harsh environments.

Its non-magnetic properties also make it suitable for use in applications where magnetic interference is a concern.

Composition & Properties

Properties

Type 303%

Carbon

.15 max

Manganese

2.00 max

Phosphorus

.20 max

Sulfur

.15 min

Selenium

NA

Silicon

1.00 max

Chromium

17.00 – 19.00

Nickel

8.00 – 10.00

Molybdenum

.60 max

Typical Mechanical Properties Annealed

Ultimate Tensile Strength, psi

90,000

.20% Yield strength psi

35,000

Elongation, % in 2″

B83

Reduction of area, %

55