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Stainless Steel 303

303 Stainless Steel belongs to the austenitic stainless steel class with great corrosion resistance and machinability. This steel grade includes sulfur to enhance the machining characteristics, and therefore it is also used in high precision machining. It is often selected for the production of screws, shafts, fittings due to good strength properties and performance in demanding industrial environments.

Material Type

Stainless Steel 303 is an austenitic stainless steel with high corrosion resistance and remarkable machinability. It forms part of the 300 series stainless steels which contains high nickel usually necessary for prevention of rust and oxidation even in harsh conditions.

Alternative Names

AISI 303 is a type of stainless steel standardized as per the requirements of the American Iron and Steel Institute. The chemical composition bears 17.0%-19.0% chromium, 8.0%-10.0% nickel, and quantifies of manganese, silicon, sulfur, and phosphorus. The high levels of chromium and nickel serve to render good corrosion resistance, while that of the sulfur improves machinability without affecting the other mechanical properties.

Process Compatibility

When it comes to processes such as machining, welding, and cold or hot working, Stainless Steel 303 is an all-purpose material. Rather, the material has a large quantity of sulfur which allows for good machining and cutting of complex parts. It is, however, a machinable alloy and requires pre or post-welding treatment approaches to attain a weld. 303 stainless steel is also used for coating systems, which provide moderate to good corrosion resistance and good polishing surface finish. These include fastener se, elements of machine construction, and food processing machinery.

Stainless Steel 303
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Jason xue

Kingsun's senior machining engineer

Stainless Steel 303 Properties

Stainless Steel 303 is workable and resistant to corrosion. As a result, it is often used in modern-day precision parts and equipment.
1

Mechanical Properties

  • Tensile Strength: 500-750 MPa
  • Proof Stress: 190 Min MPa
  • Elongation: 35 Min %
  • Hardness: 230 Max HB
2

Physical Properties

  • Density: 8.03 kg/m³
  • Melting Point: 1455°C
  • Modulus of Elasticity: 193 GPa
3

Thermal Properties

  • Thermal Conductivity: 16.3 W/m.K
  • Thermal Expansion: 17.3 x 10⁻⁶ /K
4

Electrical Properties

Electrical Resistivity: 0.72 x 10⁻⁶ Ω.m

5

Post Treatments

  • Heat Treatment: It cannot be hardened by heat treatment. Solution treatment or annealing is possible by rapid cooling after heat treatment at temperature of 1010-1120°C.
  • Welding: Provides poor weldability due to sulphur addition. The filler rods could be 308L and 309 stainless steels.
6

Common Applications

  • Nuts and bolts
  • Screws
  • Gears
  • Aircraft fittings
  • Bushings
  • Shafts

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Frequently Asked Questions (FAQs)

Q: What is the composition of 303 stainless steel?

A: Grade 303 stainless steel contains iron, chromium (17-19%), nickel (8-10%), and sulfur (0.15-0.30%) for better machinability and is thus an alloy made of austenitic stainless steel.

Q: What are the properties of grade 303 stainless steel?

A: Grade 303 stainless steel has excellent machinability and resistance to corrosion together with good mechanical properties. This steel retains its toughness, even when in an annealed condition and can be used in a wide range of applications.

Q: What kind of industries does alloy 303 commonly serve?

A: Alloy 303 is fabricated into machined components, therefore, suitable in use in parts such as gears, shafts and fasteners. It is also preferred in architectural works because of its high resistance against corrosion and excellent machinability.

Q: How does the presence of sulfur affect the machinability of 303 stainless steel?

A: Sulfur present within grade 303 stainless steel increases the ease with which the metal can be machined and still preserves good functional properties. This permits better blades movement action when cutting shapes.’

Q: Is there a specific heat treatment for this stainless steel grade 303?

A: With Grade 303 stainless steel, there is no further heat treatment to be carried out as the material has already satisfied the required properties. In most cases, it is in the annealed state which is quite common and ideal for toughness and corrosion resistance.

Q: In what types of environments will 303 stainless steel be used?

A: Yes, 303 stainless steel makes allowance for corrosion-resistant properties owing to the composition. However, under more severe conditions, silicone bronze 303 is not adequate and other alloys like 304 or 316 would be suggested.

Q: What are the normal shapes for alloy 303?

A: The most commonly supplied forms of alloy 303 are round bars, square bars, hex bars and rectangular bars as well as plenty of other forms. Such forms ensure a wide range of use during machining and manufacturing.

Q: Which one is better with respect to the properties, grade 303 or alloy 304?

A: Though grade 303 and alloy 304 are both austenitic stainless sheets of steel, 303 is more easily machined due to the sulfur contained in the steel. On the other hand, alloy 304 usually possesses a high level of corrosion resistance and toughness, which enables it to be used in more applications.

Q: What standards should be adhered to when machining parts out of 303 stainless steel?

A: Attention shall be given to the UNS specification for alloy 303 while machining parts from 303 stainless steel. This is appropriate for the intended specific use of the component in the industry considering quality and performance.

Q: Is any annealing done on the grade 303 stainless steel?

A: No, grade 303 stainless steel is usually in the annealed state during the entire course of the fabrication which implies that no further alloy annealing would be necessary for the end-use mechanical and corrosion-resistant properties.

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