303 grade is the best grade for machinability in the austenitic group, with the right tools.

Due to its Sulphur (S) content, machining is much better than all other austenitic grades. Sulphur (S) increases the machinability, however, reduces the corrosion resistance, formability and weldability.

303 grade is not suitable for deep drawing or bending. Welding is possible with the right tools, but not recommended for 303 grade.

Heat resistance is similar to 304 grade, therefore can be used up to 700°C.

Sole purpose of this grade is free machining, and for other applications other grades show better results.

Available forms: Round Bars, Flat Bars, Hexagon Bars, Square Bars

Chemical Analysis

Chemical Compositions

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

Usage Areas

  • Nuts and Bolts
  • Bushings
  • Shafts
  • Aircraft Fittings
  • Electrical Switchgear Components
  • Gears

In general any component that is heavily machined and where the corrosion resistance and fabrication properties of 303 are viable.