EN 1.4420, UNS S31655 Stainless Steel

EN 1.4420, UNS S31655 Stainless Steel

EN 1.4420, UNS S31655 Stainless Steel General Characteristics Low-Ni and low-Mo cost efficient alternative for traditional molybdenium alloyed stainless grades. 1.4420 austenitic stainless steel with its high chromium content delivers high strength, good formability and excellent weldability...
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EN 1.4420, UNS S31655 Stainless Steel

General Characteristics

Low-Ni and low-Mo cost efficient alternative for traditional molybdenium alloyed stainless grades. 1.4420 austenitic stainless steel with its high chromium content delivers high strength, good formability and excellent weldability making it ideal for use in a variety of applications including heat exchangers, water treatment and piping as well as in architectural applications such as indoor and outdoor facades. 


1.4420is an austenitic CrNiMo stainless steel with 21 wt.-% chromium and relatively low nickel and molybdenum content. Due to its high nitrogen content, 1.4420 has increased mechanical strength and shows a high degree of work hardening on mechanical deformation. 


Due to its high chromium content, 1.4420 offers similar or better corrosion resistance than austenitic CrNiMo standard grades in many corrosive environments. 1.4420 is used in applications where increased corrosion resistance and a combination of high mechanical strength and good formability are needed. 


Due to its tendency to work hardening, 1.4420 can absorb an increased amount of energy during deformation. It can be delivered in temper rolled condition with different strength levels.


Typical Applications

  • roofs & façade cladding

  • street ware & outdoor furniture

  • art & monuments

  • swimming pools

  • food & beverage industry

  • pharmaceutical industry

  • chemical industry

  • textile finishing

  • pulp & paper industry

  • stack liners

  • heat exchangers

  • storage tanks

  • tank containers

  • process equipment

  • piping

  • low temperature equipment


Chemical composition

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



CMnCrNiMoN

Typical

0.02


20.3

8.6

0.7

0.19

ASTM A240

≤0.030

≤2.00

19.5-21.5

8.0-9.5

0.50-1.50

0.14-0.25

EN 10028-7

≤0.030

≤2.00

19.5-21.5

8.0-9.5

0.50-1.50

0.14-0.25


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 among 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.


StandardRp0.2Rp1.0RmElongationRockwellHB

MPa

MPa

MPa

%



Product type: Cold rolled coil and sheet







Typical (thickness 1 mm)

380


700

45



ASTM A240

≥ 310


≥ 635


≤ 100HRB

≤ 241

EN 10028-7

≥ 350

≥ 380

650-850

≥ 35



Product type: Hot rolled coil and sheet







Typical (thickness 4 mm)

390

400

710

45



ASTM A240

≥ 310


≥ 635



≤ 241

EN 10028-7

≥ 350

≥ 380

650-850

≥ 35



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.


Fabrication

The grade can be formed using typical forming processes like folding, bending, drawing, etc. Higher strength values typically correspond to higher spring back after forming. This grade has remarkably higher proof strength than standard austenitic stainless steel grade 316L / 1.4404 in combination with same degree of work hardening. Due to the design of composition the Erichsen Index and LDR (Limiting Drawing Ratio) are matching with well-known austenitic type of stainless steels like 1.4307 or 1.4404. These characteristics mean good deep-drawability and excellent stretch forming capabilities.


Welding

1.4420 has excellent weldability and is suited to a full range of conventional welding methods (like MMA, MIG, MAG, TIG, SAW, LBW or RSW), except gas welding. 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. Austenitic 19 12 3 L (316L) filler metals can be used to get matching corrosion resistance and 22 09 NL type duplex welding consumable to get matching strength. Shielding gases should be Ar/He based or contain up to 3 % nitrogen to minimize nitrogen drop. 


Typical heat input values for austenitic grades can be utilized. High nitrogen content tends to restrict grain growth during thermal cycle. Welds are not sensitized when normal welding procedures are followed. Generally post weld heat treatment is 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.


Standards & Approvals

The steel grade is not yet included in any national standard. Work is in progress for both ASTM and EN standardization. Polarit Material Specification for the grade is available. Type X2CrNiMoN20-8-1 stainless steel. EN 1.4420* *Designation according to Stahl Eisen Liste (register of European Steels)

StandardDesignation

ASTM A240/A240M

UNS S31655

EN 10028-7, PED 2014/68/EU

1.4420


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