Supra 316L/4432
EN 1.4432, ASTM TYPE 316L

General characteristics

Supra 316L/4432 has high resistance to non-oxidizing acids and chloride-containing media due to its higher molybdenum content. Supra 316L/4432 has good formability and weldability. Supra 316L/4432 is an austenitic stainless steel that belongs to the standard CrNiMo stainless steel family. It has low carbon content for improved resistance against intergranular corrosion after welding and increased molybdenum content for slightly improved corrosion resistance.


Due to their molybdenum content, the austenitic CrNiMo standard grades can be used in applications with increased demand for corrosion resistance. Their well-balanced material properties make them suitable for the fabrication of many products.


Supra 316L/4432 is available in many product forms and dimensions. It can be supplied with a wide range of functional and aesthetic surface finishes.

 

Typical applications

  • Drinking water systems
  • Cooling systems
  • Wastewater systems
  • Flanges and valves

 

Product forms, available sizes and finishes

Flat

Product typeFinishesThicknessWidth
Black hot band1U2,70-8,501000-1650
Cold rolled coil2B, 2BB, 2C, 2D, 2E, 2G, 2H, 2J, 2K, 2M, 2R0,05-6,353-2050
Cold rolled sheet2B, 2BB, 2D, 2E, 2G, 2J, 2K, 2R0,30-6,3535-2050
Hot rolled coil, pickled1C, 1D, 1E, 1G, 1M, 1U1,46-12,7050-2050
Precision strip2R0,05-1,503-649
Quarto plate1D5,00-130,00400-3200

Long

Product typeFinishesThicknessWidth
Bloom395,00-405,00295-305
Cast slab165,00-305,001000-1585
Forged billet round200,00-230,00200-230
Forged billet square200,00-230,00200-230
Hot rolled / Black bar round75,00-230,0075-230
Peeled / turned bar round70,00-170,0070-170
Rolled billet round90,00-200,0090-200
Rolled billet square75,00-200,0075-200
Wire rod (Rod coil) hex9,00-27,009-27
Wire rod (Rod coil) round5,00-27,005-27
Wire rod (Rod coil) square9,00-24,009-24
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.

CMnCrNiMoNOther
Typical 0.0216.910.72.6
ASME II A SA-240 ≤0.08≤2.0016.0-18.010.0-14.02.00-3.00≤0.10
EN 10028-7 ≤0.030≤2.0016.5-18.510.5-13.02.50-3.00≤0.10
EN 10088-2 ≤0.030≤2.016.5-18.510.5-13.02.5-3.0≤0.10
EN 10088-3 ≤0.030≤2.0016.5-18.510.5-13.02.50-3.00≤0.10
EN 10088-3 ≤0.030≤2.0017.0-19.012.5-15.02.50-3.00≤0.10
EN 10088-4 ≤0.030≤2.016.5-18.510.5-13.02.5-3.0≤0.10
Mechanical properties

The mechanical properties of the available products in the 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.

StandardRp0.2Rp1.0RmElongationImpact strengthRockwellHBHV
 MPaMPaMPa%J
Product type: Cold rolled coil and sheet
Typical (thickness 1 mm)30033062070
ASME II A SA-240 ≥ 205 ≥ 515 ≤ 217
EN 10028-7 ≥ 240 ≥ 270550-700 ≥ 40
EN 10088-2 ≥ 240 ≥ 270550-700 ≥ 40
EN 10088-4 ≥ 240 ≥ 270550-700 ≥ 40
Product type: Hot rolled coil and sheet
Typical (thickness 4 mm)31536061550165
ASME II A SA-240 ≥ 205 ≥ 515 ≤ 217
EN 10028-7 ≥ 240 ≥ 270550-700 ≥ 40
EN 10088-2 ≥ 240 ≥ 270550-700 ≥ 40
EN 10088-4 ≥ 240 ≥ 270550-700 ≥ 40
Product type: Hot rolled quarto plate
Typical (thickness 15 mm)26028057050
ASME II A SA-240 ≥ 205 ≥ 515 ≤ 95HRB ≤ 217
EN 10028-7 ≥ 220 ≥ 260520-670 ≥ 45
EN 10088-2 ≥ 220 ≥ 260520-670 ≥ 45
EN 10088-4 ≥ 220 ≥ 260520-670 ≥ 45
Product type: Wire rod
Typical22026053055

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

Supra 316L/4432 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 diluted mineral acids depending on the temperature and concentration of the solution. Supra 316L/4432 may suffer from uniform corrosion in strong mineral acids and hot strong alkaline solutions. More detailed information on the corrosion properties of Supra 316L/4432 can be found in Outokumpu’s Corrosion Tables published in the Outokumpu Corrosion Handbook and on www.outokumpu.com.


Due to its low carbon content, the risk of sensitisation for intergranular corrosion after welding sheets up to 6 mm thick is strongly reduced when compared to basic austenitic CrNiMo grade 4401 with normal carbon content.


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. Due to its increased molybdenum content, the resistance of grade 4435 against pitting and crevice corrosion is slightly increased compared to the basic austenitic CrNiMo grades 4401 and 4404. The presence of corrosion-inhibiting or accelerating compounds like transition metal ions or organic compounds may influence the corrosion behavior of Supra 316L/4432.

 

Supra 316L/4432 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.


Supra 316L/4432 can be used for indoor and outdoor applications in rural, urban, and moderately corrosive industrial environments. When chloride contamination may be high, for instance in coastal areas, pitting and staining is possible. 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 the Outokumpu corrosion experts.

Pitting corrosion resistanceCrevice corrosion resistance
PRECPTCCT
2527±3<0

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

Physical properties according to EN 10088 are shown below.

 

DensityModulus of elasticityThermal exp. at 100 °CThermal conductivityThermal capacityElectrical resistanceMagnetizable
kg/dm3GPa10-6/°CW/m°CJ/kg°CµΩm
8.020016,0155000.75No
Fabrication

Cold forming

Supra 316L/4432 can be readily formed and fabricated using a full range of cold forming operations. It can be used in heading, drawing, and bending. Any cold forming operations will increase the strength and hardness of the material.

Hardening

Supra 316L/4432 cannot be hardened by heat treatment. However, it can be hardened by cold forming.

Hot forming

Hot forming can be carried out in the 850 °C–1150 °C range. For maximum corrosion resistance, forgings should be annealed at 1070 °C and rapidly cooled in air or water after hot forming operations.

Annealing

Quench annealing should be performed at 1030 °C–1110 °C and followed by rapid cooling in water or air. In applications where high residual stresses cannot be accepted, stress relief treatment may be necessary. This can be performed by annealing as outlined above, but may also be performed at lower temperatures.


Please contact us for further information.

Machining

Supra 316L/4432 is more difficult to machine than ordinary carbon steels but is still comparatively easier than more highly alloyed stainless grades. Unless modified for improved machinability, it requires higher cutting forces than carbon steels, shows resistance to chip breaking, and a high tendency to built-up edge formation. The best machining results are obtained by using high-power equipment, sharp tooling, and a rigid set-up. Better machinability performance is achieved using Prodec versions, which have been modified for improved machinability. Prodec is available as hot rolled plate and bar in 4401, 4404, 4436 and 4432.

 

Welding

Supra 316L/4432 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.


Supra 316L/4432 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. 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 12 3L.


Post-weld heat treatment is generally not required. In special cases with high risks 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.

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.

 

StandardDesignation
EN 10028-7, PED 2014/68/EU1.4432
EN 10088-21.4432
EN 10088-31.4432; 1.4435
EN 10088-41.4432