Prodec 303/4305
EN 1.4305, ASTM TYPE 303

General characteristics

Prodec 303/4305 is for applications that use 303/1.4305. It gives you faster machining, longer tool life, better tolerances, superior machined surface quality, and reduced scrap losses compared to conventionally produced 303/1.4305. It is an austenitic stainless steel that belongs to the standard CrNi stainless steel family. Prodec 303/4305 is a sulfur-alloyed variant with improved machinability. Due to its high sulfur content, the corrosion resistance of Prodec 303/4305 can be slightly lower than the corrosion resistance of grade 4301.

The austenitic CrNi standard grades are the most widely used group of stainless steels. Their well-balanced material properties make them suitable for the fabrication of many products.

Typical applications

  • Nuts, bolts, and screws
  • Gears
  • Shafts
  • Bearings
  • Machined parts for process equipment


Chemical composition

The typical chemical composition for this grade is given in the table below, together with composition limits given for the product according to different standards. The required standard will be fully met as specified on the order.

The chemical composition is given as % by mass.

EN 10088-21.4305≤0.10≤2.017.0-19.08.0-10.0≤0.10S:0.15-0.35
EN 10088-31.4305≤0.10≤2.0017.0-19.08.0-10.0≤0.10S:0.15-0.35
Mechanical properties

The mechanical properties of the available products in soft annealed condition at room temperature are given in the table below. Moderate strengths can be reached at elevated temperatures (~550 °C/1022 °F). Temperatures for excessive scaling are close to 850 °C/1562 °F. This grade, along with other austenitic corrosion-resistant steels, exhibits very high ductility and high elongation to fracture. It is not susceptible to brittle fracture in the solution annealed condition.

StandardGradeRp0.2Rp1.0RmElongationImpact strengthRockwellHBHV
Product type: Hot rolled quarto plate
Typical (thickness 15 mm)27558535
EN 10088-21.4305 ≥ 190 ≥ 230500-700 ≥ 35
Product type: Wire rod

1)Elongation according to EN standard:
A80 for thickness below 3 mm.
A for thickness = 3 mm.
Elongation according to ASTM standard A2” or A50.

Corrosion resistance

Prodec 303/4305 has excellent corrosion resistance in solutions of many halogen-free organic and inorganic compounds over a wide temperature and concentration range. It can withstand many organic and sufficiently diluted mineral acids depending on the temperature of the solution. Prodec 303/4305 may suffer from uniform corrosion in mineral acids and hot strong alkaline solutions. More detailed information on corrosion properties of Prodec 303/4305 can be found in Outokumpu’s Corrosion Tables published in the Outokumpu Corrosion Handbook and on

In aqueous solutions containing halogenides, e.g. chlorides or bromides, pitting and crevice corrosion may occur depending on halogenide concentration, temperature, pH-value, concentration of oxidizing compounds, or crevice geometry, if applicable. The presence of corrosion-inhibiting or accelerating compounds like transition metal ions or organic compounds may influence the corrosion behavior of Prodec 303/4305.

Prodec 303/4305 is prone to chloride-induced stress corrosion cracking at temperatures over about 50 °C depending on the applied stress and the chloride concentration in the environment. Prior cold deformation of the structure under load increases the risk of stress corrosion cracking.

Due to its high sulfur content, resistance to stress corrosion cracking, pitting, and crevice corrosion may be slightly below the typical corrosion resistance of the other austenitic CrNi standard grades.

Prodec 303/4305 can be used for indoor and outdoor applications in rural areas and urban environments where chloride contamination is low. The best material performance is usually reached with the help of adequate design, correct post-weld treatment, and regular cleaning during use (if applicable).

For more information on corrosion resistance, please refer to the Outokumpu Corrosion Handbook or contact our corrosion experts.


Pitting corrosion resistanceCrevice corrosion resistance

PRE Pitting Resistant Equivalent calculated using the formula: PRE = %Cr + 3.3 x %Mo + 16 x %N
CPT Corrosion Pitting Temperature as measured in the Avesta Cell (ASTM G 150), in a 1M NaCl solution (35,000 ppm or mg/l chloride ions).
CCT Critical Crevice Corrosion Temperature is the critical crevice corrosion temperature which is obtained by laboratory tests according to ASTM G 48 Method F



Physical properties

Typical physical properties are shown in the table below.


DensityModulus of elasticityThermal exp. at 100 °CThermal conductivityThermal capacityElectrical resistanceMagnetizable

*) Austenitic stainless steel grades may be magnetizable to a certain degree after cold deformation, e.g. in temper rolled condition.



Prodec 303/4305 is easily machined and produces small brittle chips. Prodec 303/4305 may be machined at high speeds with deep cuts and heavy feeds and still give acceptable tool life.


Prodec 303/4305 is not recommended for applications requiring welding. However, if welding is necessary, AWS E312 filler metal may be considered.

More detailed information concerning welding procedures can be obtained from the Outokumpu Welding Handbook, available from our sales offices.


Standards & approvals

Prodec 303/4305 meets AMS 5640, ASTM A 581, A 582, QQ-S-764, and MIL-S-862 specifications.


EN 10088-21.4305
EN 10088-31.4305