Fenicro®31 – Alloy 31

GENERAL INFORMATION

Fenicro®31 is Fe-Ni-Cr-Mo alloy with nitric additive.

The developed alloy fills a niche between the high-alloyed austenitic stainless steels and nickel alloys.

Fenicro®31 ideally conforms to requirements for application in the chemical and petrochemical industry, cleaning constructions and also at oil and gas production.

 It is characterized by:

- excellent anticorrosive resistance in halogen environments, as well as in acid;

- excellent resistance to sulfuric acid, even high-concentrated;

- resistance to corrosion and erosive corrosion in the phosphorus acid environments;

- special resistance to the general and local corrosion in the lixivating environment of dioxide of chlorine;

- good workability and weldability;

- it is resolved for the joints of high pressure which are operated at a temperature from -196°С to 550°С (-320 to 1020°F).

- it is allowed by ISO 15 156/MR according to the test of level VI for use of high-sulphurous gases in gas supply

Application area

  • components of systems of a desulfuration of combustion gases.
  • pulp and paper industry
  • production of chemical objects of thin organic synthesis
  • production of phosphoric acid
  • synthesis of organic acids and esters
  • recycling of sulfuric acid
  • heat exchangers for sea or salty water
  • processing of iron ore, for example HIPAL (technology of acid leaching under high pressure), method for the lateritic ores
  • Pipes and heat exchangers for sulfuric acids
  • pickling devices (H2SO4)
  • evaporation and crystallization of salts
  • oil refineries
  • pipelines and connections, pressure head pipelines for sulphurous oil gases.
  • When using sulphurous gas, Fenicro®31 is allowed to a step of VI according to ISO 15156/MR 0175 in a cold-rolled condition with the maximum hardness of 35 HRC .

 

Ppocessing and heat treatment

Hot processing by pressure.

Fenicro®31 is necessary to subject to hot processing by pressure in the field of temperatures between 1200 and 1050oС (2190-1920°F) with the subsequent hardening in water or accelerated cooling by air. Heat treatment after hot processing by pressure is recommended for achievement of optimum characteristics and the maximum corrosion properties.

For heating the processed products place in the furnace which is already warmed up to the maximum working temperature (homogenization). After the furnace reaches the temperature again, material has to be kept about 60 minutes on 100 mm of thickness.

Upon termination of the period of endurance products have to be immediately unloaded and processed in the top temperature range. After metal temperature drop below 1080oС (1980°F) repeated heating is required.

Cold processing by presure

Fenicro® 31 has higher peening than austenitic stainless steels. At the choice of devices for processing by pressure it is necessary to consider it, and the processed product has to be after diffusive annealing. At strong draftings intermediate annealings are necessary.

When draftings over 15% it is necessary to carry out repeated diffusive annealing.

 

Grades and standards

 

Country

Standard

Material description

Germany

SEW

VdTÜV-Wbl

BAM

W.-Nr.1.4562

X1NiCrMoCu32-28-7

Material is pointed in BAM list for transport with danger cargo

USA

ASTM

ASME

UNS N08031

ISO

Material is pointed in ISO 15 156/MR0175

Heating

The main importance is that the processed products before and during heat treatment remained clean and free from any impurity. Sulfur, phosphorus, lead and other fusible metals can lead Fenicro® 31 at heat treatment to embrittlement. Such impurity contain also in paints of marking and the indication of temperature or pencils and also in lubricants, oils, fuel, etc.

Fuel has to have whenever possible low content of sulfur. Natural gas has to contain less than 0,1% on the mass of sulfur. Liquid fuel with the content of at most 0,5% on weight can be used.

The atmosphere of the furnace has to be neutral to slightly oxidizing and shouldn't change between oxidizing and recovery. The processed products shouldn't be affected by fire directly.

 

Corrosion resistance

Optimum corrosion resistance is provided only in case of pure material with the relevant metallurgical structure. The chemical composition of Fenicro®31 is selected so that corrosion properties were maximum in the halogenic environments. At the same time material shows excellent stability in the pure and polluted sulfuric acid of high concentration and at a temperature to 80°С (176°F). In the conditions of stronger erosive corrosion by production of phosphoric acid Fenicro®31 proves that really is an alternative to nickel alloys. Tests in the lixivating environment of dioxide of chlorine in installations of the paper and cellulose industry have shown that Fenicro®31 maintains more severe working conditions.

Chemical composition, %

 

Ni

Cr

Fe

C

Mn

Si

Cu

Mo

N

P

S

Min

30.0

26.0

rest

 

 

 

1.0

6.0

0.15

 

 

Max

32.0

28.0

0.015

2.0

0.3

1.4

7.0

0.25

0.02

0.01

Minimal mechanical properties at room temperature for higher shapes of products acc. ASTM

Yield strength

Yield strength

Tensile strength

Elongation

Hardness

σ0,2

N/mm2

ksi

σ1,0

N/mm2

ksi

σв

N/mm2

ksi

δ5, %

НВ

≥276

≥40

≥310

≥45

≥650

≥94

≥40

max 220