Metals

Nickel Alloy 625 in Sheet, Plate and Profiles

SPECIFICATIONS: GRADE Alloy 625 | UNS N06625 | ASTM/ASME B443 / B446 | Werkstoff 2.4856 |Inconel reg TM

Castle Metals stock 1.5mm – 50mm alloy 625 (Inconel TM) in sheet and plate. With water-jet, laser, plasma and hi definition plasma processing capabilities for customer specific profiling requirements. Certified to the highest industry standards, all Castle Metals material is ready for use in the most demanding of industries.

Nickel 625 is a Nickel-Chromium-Molybdenum alloy with high strength and toughness. It has good oxidation resistance, excellent fatigue strength, and good resistance to many corrosives. Its increased strength is due to the stiffening effect of molybdenum, niobium, and tantalum.

It has excellent temperature resistance to oxidation and carburization. It is hardenable by cold working.

 

Chemical Composition (average %)

Alloy 625 Ni Cr Fe C Mn Si Mo Al Ti Nb P S
Min bal 21.0 - - - - 8.0 - - 3.2 - -
Max bal 23.0 4.0 0.025 0.40 0.40 10.0 0.40 0.40 3.8 0.010 0.010

 

Metallurgical Structure

Alloy 625 has a face-centred cubic structure. After long exposures at a temperature of about 650°C (1200°F) the alloy precipitates some isolated carbides and a metastable tetragonal phase which later changes to a stable orthorhombic phase Ni3 (Nb, Ti). The mechanical properties are enhanced by the molybdenum and niobium content through solid-solution hardening of the nickel-chromium matrix. There is, however , a loss in ductility.

Corrosion Resistance

Alloy 625 shows excellent corrosion resistance in a wide range of media:

  • Outstanding resistance to pitting and crevice corrosion in chloride-bearing media and to impingement corrosion or intergranular attack
  • High resistance to corrosive attack by mineral acids, such as nitric phosphoric, sulphuric and hydrochloric acids, as well as to alkalis and organic acids in both oxidising and reducing conditions
  • Virtual immunity to chloride-induced stress-corrosion cracking
  • Practically no corrosive attack in marine and industrial atmospheres. High resistance to seawater and brackish water , even at high temperatures
  • No sensitisation during welding
  • Good resistance to carburisation and to oxidation under static and cyclic conditions, and to chlorine containing gases
Country
National
Standards
Material
Designation
Specification
Chem.
Compo-
sition
Tube & Pipe Sheet
&
Plate
Rod
&
Bar
Strip Wire Forgings
Seamless Welded
France AFNOR NC 22 DNb                
Germany
DIN
VdTÜV
W.-Nr . 2.4856
NiCr22Mo9Nb
17744
499
17751   17750
499
17752*
499
17750
499
   
United
Kingdom
BS
NA 21       3072 3076      
USA
ASTM
ASME
AMS
ASME
Code Case
UNS N06625
Grade 1
  B444
SB444
5581
1935
B704/705
5581
B443
SB444
5581
1935
B444
SB443
5599
1935
B443
SB443
5599
1935
5837 B564
5666
ISO NiCr22Mo9Nb                
Form Dimensions Tensile
Strength
0.2% Yield
Strength
Elong
A5
%
Brinell
Hardness
HB
mm in N/mm2 Ksi N/mm2 Ksi
Sheet, Strip cr     830 120 415 60 30 150 – 220
Sheet, Plate hr ≤ 75 ≤ 3 760 110 380 55
Rod, Bar ≤ 100 ≤ 4 830 120 415 60
>100 >4 760 110 345 50
Tube, Pipe     830 120 415 60

The soft annealed, low carbon alloy 625 is widely used in chemical process technology, as its good corrosion resistance and high strength permit the use of thin structural parts. Alloy 625 is used for structures in contact with seawater and subject to high mechanical stresses.

Typical applications include:

  • Flue gas scrubber components
  • Chimney linings
  • Superphosphoric acid production equipment
  • Nuclear waste reprocessing equipment
  • Sour gas production tubes
  • Product piping systems and sheathing of risers
  • Offshore industry, marine equipment

For high-temperature applications, up to about 1000°C (1830°F), the solution- annealed, high carbon version (alloy 625, grade 2) is recommended, due to its excellent creep properties.