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AISI 303 | 1.4305 | 303S31 | X8CrNiS18-9 | Austenitic stainless steel

Material information according to DIN EN 10088-3

AISI 303, also known as BS 303S31, 1.4305 or X8CrNiS18-9, is an austenitic stainless steel that can be used at temperatures of up to 400°C. This material is typically used for machining, which is why it is also known as machining steel. As an additional alloying component, the stainless steel AISI 303 has a sulphur content of 0.15 - 0.35%, which gives it very good machinability. However, this has a negative impact on corrosion resistance, which is why it only has medium corrosion resistance and pitting corrosion (e.g. in conjunction with seawater) can occur. The PREN value is between 17.0 and 20.7, although the influence of sulphur is not taken into account here. Stainless steel 1.4305 has a tensile strength of 500 to 750 N/mm² and a hardness of ≤ 230. The yield strength is ≥ 190 mm² and the density is 7.90 kg/dm³ (at 20 °C). The material is well suited to cold drawing, but not to cold forming (cold heading and cold forming). It is not well suited to welding and forging. Stainless steel AISI 303 is very weakly magnetisable (magnetic properties μr ≤ 1.3) and cannot be polished. It is used in mechanical engineering, for decorative purposes or in the automotive industry. Machining options include automatic processing and cutting.

Product range: We offer this material in our range as stainless steel wire and as rods/bars.

Specifications of the material

EN material number: 1.4305
EN short name: X8CrNiS18-9
EN standard: 10088-3
Structure class: Austenite

Comparable standards and designations

AISI 303
BS 303S31

RVS 303
SS 2346

UNE F.3508

UNS S30300

Properties and chemical composition of stainless steel AISI 303 / 1.4305

≤ 0,10
≤ 1,00
≤ 2,00
≤ 0,045
0,15 - 0,35
≤ 0,10
17,0 - 19,0
≤ 1,00
8,0 - 10,0

Mass fraction in % according to DIN EN 10088-3
Abbreviations: C = carbon, Cr = chromium, Cu = copper, Mn = manganese, Mo = molybdenum, N = nitrogen, Ni = nickel, P = phosphorus, S = sulphur, Si = silicon, Ti = thallium.

Physical properties

Magnetisability: low
Density (kg/dm³): 7.9
Thermal conductivity (at up to 20°C): 15
Specific heat capacity (at 20°C) in J/(kg K): 500
Electronic resistance at room temperature (in Ω mm²/m): 0.73

Mechanical properties

The values given refer to the diameter range ≤ 160 (Ø in mm)*
Hardness in HB: ≤ 230
Yield strength Rp0.2 in Mpa: ≥ 190
Yield strength Rp1.0 in Mpa: ≥ 225
Tensile strength / strength Rm in Mpa: 500 - 750
Elongation A5 (longitudinal) in %: ≥ 35
* These figures refer to mechanical properties at room temperature (according to EN 10088-3)

Due to the addition of sulphur, the stainless steel AISI 303 / BS 303S31 has poor welding properties. If possible, this material should not be welded, as this can lead to the formation of hot cracks.


Stainless steel AISI 303 (1.4305 / X8CrNiS18-9) is relatively difficult to forge and requires high temperatures, which means that there is a risk of overheating and hot cracking. If forging is unavoidable, it should take place in the temperature range from 1150°C to 950°C. The subsequent cooling should take place in the air.

Cold forming

Stainless steel AISI 303 / 303S31 is well suited for cold drawing. However, due to its high sulphur content, the material is not well suited for cold forming and cold heading.

Heat treatment and hot forming

Solution annealing (+AT) (cooling by air or water): 1000 - 1100 °C
Hot forming (cooling by air): 900 - 1200 °C


AISI 303 / 1.4305 stainless steel has very good machinability, as the addition of sulphur causes short-breaking chips to form. This makes the material well suited to machining. During machining, sufficient cooling should be provided to avoid overheating.

Corrosion resistance

Stainless steel AISI 303 (1.4305 / X8CrNiS18-9) has a medium corrosion resistance (PREN value = 17.0 – 20.7* ), especially in comparison to material AISI 304 /1.4301. Due to the sulphur content, stainless steel AISI 303 has only limited corrosion resistance in media containing acid and chloride. This can lead to pitting corrosion and pitting, for example in connection with seawater or salt (NaCl). It is not resistant to intergranular corrosion.
* Please note that the harmful influence of sulphur is not taken into account here

Applications of stainless steel AISI 303 / 1.4305

Stainless steel AISI 303 (1.4305 / 303S31) is used in a variety of industries. In the automotive industry, for example, wire mesh for silencers is produced from this material. Fittings (e.g. single-lever mixers) and elements such as decorative strips and door handles are also made from this stainless steel. In the chemical and petrochemical industry, stainless steel AISI 303 is used for the construction of valves such as oil drain valves or for pipelines. Other industries that regularly use this steel are the construction industry, mechanical engineering and the food industry.

The data provided in this data sheet or material information sheet has been compiled to the best of our knowledge and is based on the current version of the relevant standard. We do not accept any liability for any errors.

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