Core 305/4303
EN 1.4303, ASTM TYPE 305 / UNS S30500

General characteristics

Core 305/4303 is a high-nickel alternative to Core 304/4301 with reduced strain hardening and excellent cold forming properties. Ideal for parts that require high deformation degrees.

Core 305/4303 is an austenitic stainless steel that belongs to the standard CrNi stainless steel family. It has 12.5 wt.-% nickel for improved formability.

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. Core 305/4303 is available in many product forms and dimensions. It can be supplied with a wide range of functional and aesthetic surface finishes.

Typical applications

  • Industrial parts with complex shapes
  • Sinks and other deep-drawn products
  • Complex stamping processes
  • Re-rollers producing very thin gauge coils


Product forms, available sizes and finishes


Product typeFinishesThicknessWidth
Cold rolled coil and sheet2B, 2E, Bright annealed0,30-6,35≤ 1524
Hot rolled coil and plateHot rolled white, Mechanically descale1,40-8,00≤ 1524
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.

TypicalCore 305/43030.0417.712.5
ASTM A240/A240MTYPE 305 / UNS S30500<0.12<217.0-19.010.5-13.0Si:<0.75 P:<0.045 S:<0.030
EN 10088-21.43030.08-0.15<1.5011.5-13.5<0.75Si:<1 P:<0.040 S:<0.015
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: Cold rolled coil and sheet
Typical (thickness 1 mm)Core 305/43032602805707077HRB
Product type: Hot rolled coil and sheet
Typical (thickness 4 mm)Core 305/43033003405705777
Product type: Hot rolled quarto plate
Typical (thickness 15 mm)Core 305/4303235265555

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

Core 305/4303 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. Core 305/4303 may suffer from uniform corrosion in mineral acids and hot strong alkaline solutions. Due to its increased nickel content, its uniform corrosion resistance usually matches or supersedes the corrosion resistance of basic austenitic CrNi standard grades 4301 and 4307. More detailed information on the corrosion properties of Core 305/4303 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. For a short period of time, for instance during cooking of food in stainless steel dishes, Core 305/4303 can tolerate even relatively high chloride concentrations. The presence of corrosion-inhibiting or accelerating compounds like transition metal ions or organic compounds may influence the corrosion behavior of Core 305/4303.

Core 305/4303 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. Due to its high nickel content, it withstands, however, stress corrosion cracking slightly better than the other austenitic CrNi standard grades with lower nickel content. Prior cold deformation of the structure under load increases the risk of stress corrosion cracking.

Core 305/4303 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).

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

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


Physical properties

Physical properties according to EN 10088 are given 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.


Cold forming

Core 305/4303 is excellent in cold forming applications like heading, drawing, and bending.


Austenitic Core 305/4303 has excellent weldability and is suitable for the full range of conventional welding methods (like MMA, MIG, MAG, TIG, SAW, LBW, or RSW), except gas welding. Core 305/4303 has about 50% higher thermal expansion and lower heat conductivity compared to carbon steels. This means that larger deformation and higher shrinkage stresses may result from welding.

In thin sections, autogenous welding may be used. In thicker section, the low-carbon Core 304L/4306 is preferred, and to ensure that the weld metal properties (e.g. strength, corrosion resistance) are equivalent to those of the parent metal, matching or slightly over-alloyed fillers should preferably be used.

The recommended filler metal is 19 9 L.

Post-weld heat treatment is generally not required. In special cases where there is high risk of stress corrosion cracking or fatigue, stress relief treatment may be considered.

In order to fully restore the corrosion resistance of the weld seam, the weld discoloration should be removed by pickling and passivation.

Because of the austenitic structure, the welded joints are tough down to low temperatures even in the as-welded condition.

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

Standards & approvals

The most commonly used international product standards are given in the table below.


ASTM A240/A240MTYPE 305 / UNS S30500
EN 10088-21.4303