Definition : 

It is the quality with the best malleability feature among the austenitics. Its malleability capability is around 78% and it is named as the automat of stainless steel. Although the sulfur (S) addition improves its malleability, it also reduces corrosion resistance (lower than 304) and weakens its formability, it is especially not suitable for straight bending. Despite sulfur, its toughness degree is the same as 304. 

Chemical Composition :

Corrosion Resistance : 

Corrosion resistance in warm environments is good but low in 304, and due to sulfur (S), the sulfur addition causes partial wear. For this reason, it is not recommended to be used at sea side or in related sectors since sulfur creates corrosive wear in transverse sections in the inner structure of material.
303 quality shows reaction at the rates like 304 does in normal conditions and hot aqueous settings above 60 °C.

Heat Resistance : 

303 has a good oxidation resistance in environments which become 760 °C with intervals and continuously become 870 °C. However, at settings with 425-860 °C, carbide sedimentation occurs.

 Heat Treating (Annealing) : 

After annealing process is heated between at 1010-1120 °C, it is quickly cooled. It can not be hardened by heat treatment.

Mechanic Features :

Physical Features :

Areas of Use :

Bolts, nuts, screws, etc.
Coupling, shaft
Aircraft fittings
Electric gear elements
Gears
The corrosive environment where 303 is suitable, machine parts with a high processing ratio