AUSTENITIC SPHEROIDAL AND FLAKE GRAPHITE IRONS

These alloys (commonly known as Ni Resists) are a family of alloy cast irons in which the addition of a substantial proportion of nickel, together with other elements, has produced a fully austenitic structure, and mechanical and physical properties unobtainable from ordinary grey cast iron.

The combined effect of a high alloy content and an austenitic matrix gives the Ni Resist cast irons outstanding resistance to many types of corrosion and erosion, and to the effects of elevated temperatures. They are also stronger and tougher than grey iron, have good wear and galling resistance, high electrical resistance and good machinability.

By choice of suitable composition, Ni Resist irons can be made magnetic or slightly magnetic. By the same means the coefficient of thermal expansion can be varied over a wide range.

Chemical Composition for Flake Graphite Austenitic Iron.

Allen

AS1833-2002

Composition, per cent

Foundry

Grade

Carbon

Silicon

Manganese

Chromium

Copper

Nickel

Alloy Type

L-

Min

Max.

Min.

Max.

Min.

Max.

Min.

Max.

Min.

Max.

Min.

Max.

NR1

Ni Cu Cr 15 6 2

-

3.0

1.0

2.8

0.5

1.5

1.0

2.5

5.5

7.5

13.5

17.5

NR1B

Ni Cu Cr 15 6 3

-

3.0

1.0

2.8

0.5

1.5

2.5

3.5

5.5

7.5

13.5

17.5

NR2

Ni Cr 20 2

-

3.0

1.0

2.8

0.5

1.5

1.0

2.5

-

0.5

18.0

22.0

NR2B

Ni Cr 20 3

-

3.0

1.0

2.8

0.5

1.5

2.5

3.5

-

0.5

18.0

22.0

Nicrosilal

Ni Si Cr 20 5 3

-

2.5

4.5

5.5

0.5

1.5

1.5

4.5

-

0.5

18.0

22.0

NR3

Ni Cr 30 3

-

2.5

1.0

2.0

0.5

1.5

2.5

3.5

-

0.5

28.0

32.0

NR4

Ni Si Cr 30 5 5

-

2.5

5.0

6.0

0.5

1.5

4.5

5.5

-

0.5

29.0

32.0

NR5

Ni 35

-

2.4

1.0

2.0

0.5

1.5

-

0.2

-

0.5

34.0

36.0

Chemical Composition for Spheroidal Graphite Austenitic Iron.

Allen

AS1833-2002

Composition, per cent

Foundry

Grade

Carbon

Silicon

Manganese

Phosphorus

Chromium

Copper

Nickel

Alloy Type

S-

Max.

Min.

Max.

Min.

Max.

Max.

Min.

Max.

Min.

Max.

Min.

Max.

NRD2

Ni Cr 20 2

3.0

1.5

3.0

0.5

1.5

0.08

1.0

2.5

-

0.5

18.0

22.0

NRD2B

Ni Cr 20 3

3.0

1.5

3.0

0.5

1.5

0.08

2.5

3.5

-

0.5

18.0

22.0

Spheronic

Ni Si Cr 20 5 2

3.0

4.5

5.5

0.5

1.5

0.08

1.0

2.5

-

0.5

18.0

22.0

AUS203

Ni 22

3.0

1.0

3.0

1.5

2.5

0.08

-

0.5

-

0.5

21.0

24.0

NRD2M

Ni Mn 23 4

2.6

1.5

2.5

4.0

5.0

0.08

-

0.2

-

0.5

22.0

24.0

NRD3A

Ni Cr 30 1

2.6

1.5

3.0

0.5

1.5

0.08

1.0

1.5

-

0.5

28.0

32.0

NRD3

Ni Cr 30 3

2.6

1.5

3.0

0.5

1.5

0.08

2.5

3.5

-

0.5

28.0

32.0

NRD4

Ni Si Cr 30 5 5

2.6

5.0

6.0

0.5

1.5

0.08

4.5

5.5

-

0.5

28.0

32.0

NRD4

Ni 35

2.4

1.5

3.0

0.5

1.5

0.08

-

0.2

-

0.5

34.0

36.0

NRD5

Ni Cr 35 3

2.4

1.5

3.0

0.5

1.5

0.08

2.0

3.0

-

0.5

34.0

36.0

 

AUSTENITIC SPHEROIDAL AND FLAKE GRAPHITE IRONS

Mechanical and Physical Properties of Spheroidal

and Flake Graphite Austenitic Iron.

Allen Foundry

AS1833-2002

Tensile Strength

0.2% Proof Stress

Elongation

Brinell Hardness

Thermal Coeff. of Expansion

Alloy Type

Grade

MPa (min.)

MPa (min.)

% (min.)

HB (min.)

*

NR1

L-Ni Cu Cr 15 6 2

170

-

2

140

18.7

NR1B

L-Ni Cu Cr 15 6 3

190

-

1-2

150

18.7

NR2

L-Ni Cr 20 2

170

-

2-3

120

18.7

NR2B

L-Ni Cr 20 3

190

-

1-2

160

18.7

Nicrosilal

L-Ni Si Cr 20 5 3

190

-

2-3

140

18.0

NR3

L-Ni Cr 30 3

190

-

1-3

120

12.4

NR4

L-Ni Si Cr 30 5 5

170

-

-

150

14.6

NR5

L-Ni 35

120

-

1-3

120

5.0

NRD2

S-Ni Cr 20 2

370

210

7

140

18.7

NRD2B

S-Ni Cr 20 3

390

210

7

150

18.7

Spheronic

S-Ni Si Cr 20 5 2

370

210

10

180

18.0

AUS203

S-Ni 22

370

170

20

130

18.4

NRD2M

S-Ni Mn 23 4

440

210

25

150

14.7

NRD3A

S-Ni Cr 30 1

370

210

13

130

12.6

NRD3

S-Ni Cr 30 3

370

210

7

140

12.6

NRD4

S-Ni Si Cr 30 5 5

390

240

Not indicated

170

14.4

NRD4

S-Ni 35

370

210

20

130

5.0

NRD5

S-Ni Cr 35 3

370

210

7

140

5.0

               *   (20-200oC) m/m. K x 10-4

                    TYPICAL APPLICATIONS

                    (of some Ni Resist Irons)

NR1 Good heat resistance, good bearing properties, high thermal expansion and non-magnetic.

Good resistance to corrosion in alkalis, dilute acids, sea water and salt solutions.

Applications include: pumps, valves, furnace components, piston ring inserts for light alloy metal pistons.

NR2 Similar to NR1 but is more corrosion resistant to alkalis. It is preferred for heat and oxidation resistant service up to 700oC.

Applications include: pumps handling alkalis, uses in soap, food and plastics industries and in applications where copper-free materials are required.

NR5 Resistant to thermal shock and has a low coefficient of thermal expansion.

Applications include: parts with dimensional stability, such as machine tools, scientific instruments and expansion joints.

NRD3 Resistant to thermal shock up to 800oC. Good corrosion resistance at high temperatures and excellent erosion resistance in wet steam and salt slurry. Applications include: pumps, boilers, valves, exhaust gas manifolds and turbo/ supercharger housings.

NRD5 Similar to NR5 but more resistant to thermal shock.   Similar applications to NR5

                    Impeller                                 Bowl