303 Stainless Steel – Data Sheet, Advantages, Applications
The stainless steel with the material number 303 is an austenitic chromium-nickel steel with added sulfur. The addition of sulfur increases the machinability of the material. As many steel grades have medium to poor machinability, 303 steel is used in many areas where other stainless steels such as 1.4301 (304) and 1.4401 (316) cannot fulfil the requirements.
Chemical composition – data sheet
Sulfur is present as an alloying element at a maximum of 0.35%. This amount is already sufficient to significantly improve the machinability of the material.
The stainless steel with the material number 303 is an austenitic material with a sulfur alloy. The addition of sulfur increases the machinability of the metal. Since many grades have medium to poor machinability, 303 is used in many applications where other stainless steel types such as 304 and 316 cannot meet the requirements.
| C | Si | Mn | P | S | Cr | Cu | N | Ni |
| ≤ 0.1 % | ≤ 1 % | ≤ 2 % | ≤ 0.045% | 0.15 – 0.35% | 17 – 19% | ≤ 1% | ≤ 0.11% | 8 – 10% |
The austenitic steel is known internationally by the AISI designation 303, as well as the alloy designation X8CrNiS18-9 and UNS number S30300. A variation of 303 is the material AISI 303Se, in which selenium is used as an alloying element instead of sulfur. The selenium does not increase machinability as much as the sulfur, but in return allows better machinability in cold and hot working.
Advantages and properties
One of the most important advantages of material 303 is its very good machinability. Unlike many other grades, it exhibits a smooth surface after machining operations, such as milling. Other stainless steel grades must be shaped by forming or casting, as their surface requires a great deal of post-polishing effort when machined. 303 is not suitable for forging anyway and should only be cold worked, as the material is prone to hot cracking.
However, the sulfur alloy also affects other mechanical properties. For example, corrosion resistance in acidic environments is poorer than many other types of steel. However, 303 can not be hardened by heat treatment. However, the alloy can be hardened by our BORINOX® process for stainless steel hardening.
Application areas
303 is suitable for many applications, whereas common applications are:
- Automotive industry
- Mechanical engineering
- Fittings, especially for decorative purposes
- Electronic equipment
- Chemicals, petrochemicals
- Food industry
