Nickel Alloy 625 – Properties, Composition, Corrosion Data and Specifications from Super Alloys

Topics Covered

Background

 

Background

The Super Alloys management team are amongst the most experienced professionals in the market. Supported by professional metallurgists and technicians, Super Alloys not only provide access to the largest range of high-tec metals in Europe, but also access to the broadest range of expertise.

The unique combination of access to stock, expertise and rapid delivery reduces lead times and can eliminate costly production delays.

The Super Alloys range of materials includes:

         Titanium Alloys

         Nickel Alloys

         Steels

Nickel Alloy 625

Nickel Alloy 625 is used both for its high strength and outstanding aqueous corrosion resistance. The strength of Nickel Alloy 625 is primarily a solid solution effect from molybdenum and columbium. Nickel Alloy 625 has excellent weldability. The matching filler metals are often used for dissimilar metal joining and to weld the aqueous corrosion alloy AL-6XN®.

Features of Nickel Alloy 625

The key features of Nickel Alloy 625 include:

         Outstanding resistance to chloride pitting and crevice corrosion cracking

         Immune to chloride ion stress corrosion cracking

         Resistant to caustics

         Resistant to seawater, in both flowing and stagnant • conditions, and under fouling

Applications of Nickel Alloy 625

Typical Applications for the Nickel Alloy 625 include:

         Chemical process equipment handling mixed acids both oxidizing and reducing

         Flue gas desulfurization scrubbers

         Evaporators for wet-process phosphoric acid containing H2SO4, HF and ferric salts

         Weld Overlay

Composition of Nickel Alloy 625

The composition range for Nickel Alloy 625 is provided in table 1.

Table 1. Composition of nickel alloy 625.

Chemistry, %

AMS 4967

 

Min

Max

Chromium

20.00

23.0

Nickel

58.00

Balance

Molybdenum

8.00

10.00

Cobalt

-

1.00

Columbium + Tantalum

3.15

4.15

Aluminum

-

0.40

Titanium

-

0.40

Carbon

-

0.10

Iron

-

5.00

Manganese

-

0.50

Silicon

-

0.50

Phosphorus

-

0.015

Sulfur

-

0.015

Specifications

The various forms of nickel alloy 625 are covered by the following standards:

         UNS/W. Nr N06625/2.4856

         Rod and bar ASTM B 446 and ASME SB-446 Gr 1

Physical Properties of Nickel Alloy 625

Density:

0.305 lb/inch3

Melting Range:

2350-2460°F

Thermal Properties of Nickel Alloy 625

The thermal properties of Nickel Alloy 625 are summarised in table 2.

Table 2. Thermal properties of Nickel Alloy 625.

Temp

Coefficient of Thermal Exp.

Thermal Conductivity

Modulus of Elasticity Dynamic

°F

in/in °F x 10-6

Btu. ft/ft2.hr°F

psi x 106

70

-

5.7

29.8

400

7.3

7.2

28.4

600

7.4

8.2

27.5

800

7.6

9.1

26.6

1000

7.8

10.1

25.6

1200

8.2

11.0

24.4

1400

8.5

12.0

23.1

1600

8.8

13.2

-

Typical Mechanical Properties of Nickel Alloy 625

The minimum mechanical properties of nickel alloy 625 are provided in table 3.

Table 3. Minimum Specified Tensile Properties, Room Temperature ASTM B 446 Bar, Grade 1

Property

Value

Ultimate Tensile Strength

120 ksi

0.2% Yield

60 ksi

Elongation (2”)

30%

Corrosion Resistance of Nickel Alloy 625

Table 4. Corrosion by quiet & flowing seawater, Wrightsbille Beach, NC.

Alloy

 

Quiet

 

Flowing, 2 ft/sec

 

Weight Loss, g

Range of Pit Depth, mils

Weight Loss, g

Range of Pit Depth, mils

 

 

Panel

Crevice Area

 

Panel

Crevice Area

625

Nil

Nil

Nil

0.25

Nil

Nil

C-276

Nil

Nil

Nil

0.10

Nil

Nil

René 41 

0.80

Nil

Nil

0.30

Nil

Nil

0.10

Nil

Nil

0.60

Nil

Nil

825 

0.25

0-1

0-9

0.20

3-6

1-26

718 

2.70

Nil

37-165P

5.15

Nil

40-165P

Test duration two years. P=perforated by local attack

Table 5. Crevice corrosion temperature (CCT).

Alloy

 UNS No.

Molybdenum Content

 °C

 °F

 Pitting Resistance Equivalent, (PRE)N

316L

S31603

2.1

-3

27

23

825

N08825

2.7

-3

27

30

2205

S31803

3.1

20

68

38

317L

S31703

3.2

2

35

29

AL-6XN®

N08367

6.2

43

110

48

625

N06625

9.0

45

113

51

C-276

N10276

15.4

55

130

66

10% FeCl3.6H2O, per ASTM G 48 Practice B

(PRE) N=Cr + 3.3Mo + 16N

 

 

Source: Super Alloys

 

For more information on this source please visit Super Alloys.

 

Date Added: Apr 30, 2008
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