Fenicro®20 – Alloy 20

GENERAL INFORMATION

Fenicro®20 is Ni-Fe-Cr alloy with the low content of carbon, with the alloying additive of copper and molybdenum, austenitic stabilized by niobium.

Main characteristics Fenicro®20:

  • excellent sulfuric and phosphoric acids resistance.
  • good resistance of intercrystalline corrosion.
  • very good resistance to the corrosion cracking caused by chlorine ions.
  • resistance to pitting and crevice corrosion.
  • good mechanical properties, both at room, and at the high temperatures approximately up to 500°С (930°F).

Application area

Fenicro®20 is widely used at temperatures up to 500°С (930°F).

Typical fields of operation:

•the equipment for production of sulfuric acid and also the processes which are based on use of sulfuric acid.

•extraction columns in production of amino acids and for production of medications.

•production of synthetic and plastic fibers

•equipment for production of food

 

 

Ppocessing and heat treatment

Fenicro®20 it is convenient in the course of deformation in heated condition, as well as in cold, it is well processed by cutting and weld well

Cold deformation

Cold deformation is carried out in the annealed condition.

Fenicro®20 shows higher rates of cold hardening, than austenitic stainless steels that has to be considered at the choice of the form-building device.

At cold deformation with high reduction ratio it is necessary to apply intermediate annealing.

At cold deformation from 15% of reduction ratio the final stabilizing annealing has to be carried out.

Heat treatment

The softening or stabilizing annealing has to be carried out at temperatures 920°С-960°С (1690-1760°F) , preferably at 950°С (1740°F).

For achievement of the maximal corrosion resistance the subsequent hardening in water is obligatory. At a thickness of product less than 3 mm the accelerated cooling on air can be carried out. Stress relieving annealing is carried out at 540°С (1000 °F).

At each heat treatment the ordered requirements of purity have to be observed.

 

 

 

Grades and standards

 

Country

Standard

Material description

Germany

DIN

VdTÜV

W.-Nr.2.4660

NiCr20CuMo

USA

ASTM

UNS N08020

 

ISO

FeNi35Cr20Cu4Mo2

Heating

Products have to be cleaned previously and kept in purity during heat treatment.

Sulfur, phosphorus, lead and other fusible metals can lead at heat treatment to embrittlement. Similar impurity contain in marking paints, lubricants, oils, fuel.

Combustible materials with the minimum quantity of sulfur are recommended. The sulfur share in natural gas shouldn't exceed 0,1% on general weight. It is admissible to have liquid fuel with max. 0,5% on the weight of sulfur in general content.

The atmosphere in the furnace is established within neutral and to easily oxidizing and shouldn't fluctuate between oxidizing and restoring. Products shouldn't be exposed to direct influence of a flame.

Electric furnaces are recommended for providing exact temperature conditions and the maximal purity of a product. The furnaces warmed by gas are used, but at a low indicator of impurity.

 

Hot deformation

Fenicro®20 is exposed to hot deformation in a temperature interval 1150°С - 900°С (2100°F - 1650°F), final temperature of hot deformation shouldn't go beyond 950°С(1740°F) with the subsequent hardening in water or faster cooling. It is required to carry out heat treatment after hot deformation of material for obtaining optimum corrosion properties and fine-grained structure.


For hot deformation material has to be placed in the furnace warmed up to the maximal working temperature. After holding during necessary time it has to be immediately processed in the specified range of temperatures. At temperature drop below the minimal working range, repeated heating is necessary.

Chemical composition, %

 

Ni

Cr

Fe

C

Mn

Si

Cu

Mo

Nb

P

S

Min

36.5

19.0

rest

 

1.0

 

3.0

2.0

0.1

 

 

Max

38.5

21.0

0.02

2.0

0.7

4.0

3.0

0.3

0.02

0.005

Mechanical properties

Temperature (Т)

Yield strength

Yield strength

Tensile strength

Elongation

Hardness

°С

°F

σ0,2

N/mm2

ksi

σ1,0

N/mm2

ksi

σв

N/mm2

ksi

δ5, %

НВ

20

68

240

35

280

40.6

550

80

30

≤217