Indaten® 355A

Alternative and trade names
Ensacor® A
Want to keep this datasheet? Save it now in your required format


Indaten® 355A is a steel with improved resistance to atmospheric corrosion that meets the requirements of the EN 10025-5:2004 standard. This grade is fine-grain, high-strength structural steel that has been optimised to give improved processing and in-service performance.

With its characteristic colour, Indaten® 355A steel is used in architectural projects either to harmonise with the environment or to create a pleasing contrast with other materials, such as stainless steel. When used uncoated and exposed to bad weather, an oxide layer develops on the steel surface, forming a purplish-brown, finely grained patina that bonds very strongly to the steel and protects it. If the patina is damaged, the steel re-oxidises, thus repairing the patina and maintaining the protective barrier. Indaten® 355 can also be coated (paint, metallic coatings etc). In the case of coated parts, the protective layer prevents rust propagation under the paint layer.

Experience has shown that the adhesion of organic coatings on Indaten® 355A is superior to bonding on other carbon steel grades.

Related Standards

Equivalent Materials

This material data has been provided by ArcelorMittal.

"Typical" values were obtained via a literature search. "Predicted" values were imputed via artificial intelligence technology. While we have placed significant efforts in ensuring data accuracy, "typical" and "predicted" data should be considered indicative and verified by appropriate material testing. Please do contact us if additional information on the the predicted data method is required.
All metrics apply to room temperature unless otherwise stated. SI units used unless otherwise stated.
Equivalent standards are similar to one or more standards provided by the supplier. Some equivalent standards may be stricter whereas others may be outside the bounds of the original standard.

Ashby charts




Carbon equivalent (CEV)

0.45 [-]

Show Supplier Material materials with Carbon equivalent (CEV) of 0.45 [-]





Please feel free to check the figure on the right side of the material page for more details.



Bend allowance

1.5 [-]

Show Supplier Material materials with Bend allowance of 1.5 [-]

min. | for thickness 1.7-3 mm

2 [-]

Show Supplier Material materials with Bend allowance of 2 [-]

min. | for thickness 3-10 mm

3 [-]

Show Supplier Material materials with Bend allowance of 3 [-]

min. | for thickness 10-16 mm

Charpy impact energy

0 °C

27 J

Show Supplier Material materials with Charpy impact energy of 27 J

min. | for thickness 6-20 mm | For impact resistance at lower temperatures please check with ArcelorMittal technical representative.


18 %

Show Supplier Material materials with Elongation of 18 %

min. | for thickness 1.7-3 mm | Transverse, A80

22 %

Show Supplier Material materials with Elongation of 22 %

min. A5.65√So | for thickness 3-16 mm | Transverse

Tensile strength

490 - 630 MPa

Show Supplier Material materials with Tensile strength of 490 - 630 MPa

for thickness 3-16 mm | Transverse

510 - 680 MPa

Show Supplier Material materials with Tensile strength of 510 - 680 MPa

for thickness 1.7-3 mm | Transverse

Yield strength

355 MPa

Show Supplier Material materials with Yield strength of 355 MPa

min. | for thickness 1.7-16 mm | Transverse

Chemical properties



0.02 %

Show Supplier Material materials with Aluminium of 0.02 %



0.12 %

Show Supplier Material materials with Carbon of 0.12 %



0.3 - 0.8 %

Show Supplier Material materials with Chromium of 0.3 - 0.8 %


0.3 - 0.8 %

Show Supplier Material materials with Copper of 0.3 - 0.8 %


1 %

Show Supplier Material materials with Manganese of 1 %



0.3 %

Show Supplier Material materials with Nickel of 0.3 %



0.009 %

Show Supplier Material materials with Nitrogen of 0.009 %



0.06 - 0.15 %

Show Supplier Material materials with Phosphorus of 0.06 - 0.15 %


0.2 - 0.5 %

Show Supplier Material materials with Silicon of 0.2 - 0.5 %


0.015 %

Show Supplier Material materials with Sulfur of 0.015 %


Technological properties

Application areas

Indaten® 355 has a wide range of applications: architecture, sculpture, engineering structures, smokestacks, freight wagons, silos, containers and pylons. When used uncoated, no maintenance is required and the material will not deteriorate through corrosion.

The effectiveness of the corrosion protection largely depends on the speed of patina formation. For optimum patina formation, Indaten® 355 can be used in a non-confined environment, even in the presence of sulphuric fumes. However, it is strongly recommended not to expose Indaten® 355 to condensation or repeated soiling, particularly in environments containing free chlorine.

Since 1 July 2013, the Construction Products Regulation (Regulation (EU) No. 305/2011 – CPR) has required that CE marking be affixed to all products delivered in accordance with a harmonised standard (e.g. EN 10025). This CE marking guarantees, for the uses defined in the standard, the properties described in the declaration of performance submitted by the manufacturer.

The steel comply with this Regulation.

The corresponding declarations of performance are available on our website at:

Chemical composition

The above chemical properties are based on cast analysis data.


Galvanisation: No

Corrosion properties

Corrosion in a salt spray atmosphere (according to ASTM B117)

Tests were conducted in a chamber at a temperature of 35°C, in a humid atmosphere with a 5% concentration of NaCl. Weight loss was measured after 1000 hours. The sample was weighed before and after the test, and the rust was removed with an acid solution.

Atmospheric corrosion

The samples were exposed to an industrial, marine atmosphere for 12 months.

Please reefer to the figures on the rigth side of the page.

Delivery condtion

The grade as per EN 10025-5 can be supplied:

Without any special rolling and/or heat treatment requirements. The abbreviated designation of this delivery condition is +AR. Following a rolling process in which final forming is carried out within a certain temperature range, producing a material in a condition equivalent to that obtained after normalising, with the result that the specified mechanical properties values are conserved even after normalising treatment. The abbreviated designation of this delivery condition is +N.

Furthermore, option 11c of EN 10025-5 is also available (sheet, plate, strip, wide flats and flats (width < 150 mm) with a nominal thickness ≤ 20 mm shall be suitable for flanging without cracking).


Recommendations for use

Appearance of the patina

Outdoor use: the patina forms naturally in the open air (over a period of three to four years). Variations in appearance will be observed, depending on the water condensation, evacuation and evaporation conditions. After a few years, the patina will stabilise, even in an industrial, sulphur-containing or rural environment. To ensure optimum patina formation and limit the formation of rust streaks, the oxidation process can be accelerated artificially by first descaling the surface (by sandblasting or shotblasting) and then subjecting it to alternate periods of dry and humid conditions.

Indoor use: to preserve the natural appearance of the material and at the same time avoid powdery oxide deposits that may cause staining, the following three steps are recommended:

First remove all dusty deposits, stains or surface defects, then apply a chemical treatment to those areas where corrosion has not yet developed Clean the surface with water, brush and dry

Finally, apply a colourless, matt, UV-resistant varnish Use painted: as the surface has a high reactivity, it is recommended that the first coat of paint be applied on a clean surface immediately after pickling or sandblasting. The presence of copper in the oxide layer contributes to the formation of a strongly bonded, elastic and compact patina on the surface of Indaten® 355 in the course of the corrosion process. The chromium and nickel contribute to the formation of insoluble alkaline sulphates, which will seal the pores of the oxide layer, thereby protecting the metal from water and oxygen. Silicon, and to a lesser extent phosphorus, also has a favourable effect on corrosion resistance.


Indaten® 355 has excellent weldability with all the usual welding processes thanks to its low carbon content and fine-grained structure.

Shielded metal arc welding (process no. 111, SMAW)

SupplierReferenceEN ISOAWS
EsabOK 73.08*2560-A / E 46 5 Z B 32A5.5 / E8018-G
OK 48.08*2560-A / E 42 4 B 32 H5A5.1 / E7018
Lincoln ElectricConarc 55CT SRP*499 / E 46 5 Mn1Ni B 32 H5A5.5 / E8018-W2-H4R
Conarc 60G**757 / E 55 4 Z B 32 H5A5.5 / E9018M-H4
Conarc 70G**757 / E 55 4 1NiMo B 32 H5A5.5 / E9018-G-H4
S.A.F. Air LiquideSafer CU 56**499 / E 464 Z B 32 H5A5.5 / E8018-G
Safer NF 52**499 / E 424 B 54 H5A5.5 / E7028
499 / E 423 B 74 H5
Safer NF 510**499 / E 423 B 32 H5A5.5 / E7018
ThyssenSH Patinax KB**499 / E 38 3 Z 1 NiCu B 42A5.5 / E7015-G
*Specific electrode. ** Specially adapted electrode

Submerged arc welding (process no. 21, SAW)

The filler materials to be used are the same as those recommended for welding steels with the same mechanical properties. As SAW involves strong inherent dilution, the welds will develop a patina. The mechanical properties obtained in fusion zones meet the normal mechanical property requirements for the base metal.

SupplierReferenceEN ISOAWS
EsabFil Autrod 13.36*756 / S2Ni1CuA5.23 / EG
OK Flux 10.71 and 10.81 to 10.83*

Lincoln ElectricFil LNS 163*
Flux P230*760 / S A AB 1 67 AC H5
Fil L60**756 / S1A5.17 / EL12
Flux 780**760 / S A AR/AB 1 78 AC H5
Fil L61**S2SiA5.17 / EM12K
Flux 860**760 / S A AB 1 56 AC H5
S.A.F. Air LiquideFil AS 26**756 / S1A5.17 / EL12
Flux AS 50**756 / SF 35 0 MS 1 S 1A5.17 / F6-A0-EL12
Fil AS 35**756 / S2A5.17 / EM12K
Flux AS 50**756 / SF 38 0 MS 1 S 2A5.17 / F7-A0-EM12K
ThyssenUnion Patinax U*756 / S 42 2 FB S0A5.23 / F7A2-EG-G
Flux UV 420 TT / UV 420 TT-LH*760 / SA FB 1 65 DC / SA FB 1 65 DC H5
*Specific welding wire/flux couple ** Specially adapted welding wire/flux couple

Gas metal-arc welding (process no. 135, GMAW)

The thin wires used for equivalent carbon steel grades can also be used for Indaten® 355 steels; copper-plated wires deposit more copper on the surface of the welded zone, which contributes to the development of a patina on the welds. The cored wires to be used are also the same as those used for the equivalent carbon-manganese steel grades.

SupplierReferenceEN ISOAWS
EsabOK Autrod 12.51**440 / G3Si1A5.18 / ER70S-6
OK AristoRod 13.29**12534 / GMn3Ni1CrMoA5.28 / ER110S-G
Lincoln ElectricLNM 28*12070 / G465MG3Ni1A5.28 / ER80S-G
LNM Ni1** A5.28 / ER80S-Ni1
S.A.F. Air LiquideNertalic 70 A**440 / G3Si1A5.18 / ER70S-6
ThyssenUnion Patinax*440 / G423CGOA5.18 / ER70S-G
* Specific welding wire ** Specially adapted welding wire

Flux-cored arc welding (process no. 136, FCAW)

The process is suitable for the assembly of thin products with the same welding parameters recommended for equivalent carbon-manganese steel grades. If a filler wire is used, it must be of the same type as the base metal.

SupplierReferenceEN ISOAWS
EsabOK Tubrod 14.01*17632-A / T 42 2 Z M M 2 H10A5.18 / E70C-GM
OK Tubrod 15.00**758 / T 42 3 B M 2 H5A5.20 / E71T-5H4
758 / T 42 3 B C 2 H5A5.20 / E71T-5MH4
OK Tubrod 15.17**758 / T 46 4 1Ni P M 2 H5A5.29 / E81T1-Ni1M
758 / T 46 3 1Ni P C 2 H5
Lincoln ElectricOutershield 500CT-H*758 / T 50 5 Z P M 2 H5A5.29 / E81T1-G-H4
S.A.F. Air LiquideSafdual 31*758 / T 42 4 B M 2 H5A5.20 / E71T5
Safdual 248*758 / T 46 A Z MM 1 H5A5.29 / E81T1G-W2M
* Specific welding wire. ** Specially adapted welding wire