N-155 (MULTIMET) TECHNICAL DATA


Type Analysis | Description | Physical Properties | Heat Treatment
Workability | Corrosion Resistance | Typical Mechanical Properties

Type Analysis

Element

Min

Max

Carbon

0.08

0.16

Manganese

1.00

2.00

Silicon

--

1.00

Sulfur

--

0.03

Chromium

20.0

22.5

Nickel

19.0

21.0

Copper

--

0.50

Tungsten

2.00

3.00

Iron

Balance

Cobalt

18.5

21.0

Columbium*

0.75

1.25

Nitrogen

0.10

0.20

Molybdenum

2.50

3.50

Phosphorus

--

0.04

* plus Tantalum

Description

N-155 alloy has high temperature properties which are inherent and do not depend upon age hardening. It is recommended for applications involving high stresses at temperatures up to 1500°F, and can be used up to 2000°F where only moderate stresses are involved. It has good ductility, excellent oxidation resistance, and can be readily fabricated and machined.
N-155 is recommended for parts which must possess good strength and corrosion resistance up to 1500°F. It is used in numerous aircraft applications such as tail cones and tailpipes, exhaust manifolds, combustion chambers, afterburners, turbine blades and buckets, and bolts.


Physical Constants:

Density - lb/cu in................................................... 0.298
                kg/cu m................................................... 8249
Melting range.....................2350/2470°F (1288/1354°C)
Electrical resistivity
   ohm-cir mil/ft at 72°F........................................... 558
   microhm-mm at 22.2°C......................................... 930
Specific heat
   Btu/lb-°F (70/212°F)........................................... 0.104
   kJ/kg-K (21/100°C).............................................. 0.435

Thermal conductivity

Temperature

Btu-in/ft²-hr-°F

W/m-K

°F

°C

392
572
752
932
1112

200
300
400
500
600

101
110
120
129
139

14.6
15.9
17.3
18.6
20.0

Coefficient of thermal expansion:

Temperature

10(-6)/°F

K(-1)

70°F to

21.1°C to

212
392
572
752
932
1112
1292
1472
1652
1832
2012

100
200
300
400
500
600
700
800
900
1000
1100

7.90
8.50
8.51
8.58
8.98
9.32
9.60
9.81
9.98
10.14
10.28

14.2
15.3
15.3
15.4
16.2
16.8
17.3
17.7
18.0
18.3
18.5

Modulus of elasticity:

Temperature

psi x 10(6)

MPa x 10(3)

°F

°C

70
1000
1500

21.1
538
816

29.25
24.20
20.80

202
167
143


Heat Treatment:

Solution Treatment:
Heat to 2100/2280°F, hold for 1 hour at heat, and cool rapidly. The best ductility is obtained by treating at the lower temperature while treating at the higher temperature produces the highest rupture strength.

Aging Treatment:
Heat to 1400/1500°F, hold approximately 16 hrs at heat , and air cool.

Hardness Values:

Condition                                                      Brinell             Rockwell
Hot worked...................................................  277                     C 29
Solution Treated 2200°F (1204°C)
   water quenched..........................................  217                      B 96
Solution Treated 2200°F (1204°C)
    water quenched
     + aged 1500°F (816°C)............................  230                      C 20

Workability

Hot Working:
Forging of ingots should be conducted from about 2200°F (1204°C) after being thoroughly soaked. Hot rolling of finished sizes from semifinished hot-worked material should be conducted at 2050/2150°F, and the finishing temperature should be kept as high as pracitcal under the hot working conditions.

Machining
A rigid setup, low cutting speeds and ample coolant flow are recommended. Following are suggested angles for single point tungsten carbide tools: 8 to 10° side rake angle, 5 to 8° back rake angle, 5 to 7° end relief angle, 15 to 30° side cutting edge angle. Radius of nose -1/32". The included angle of high speed drills should be ground to 135 to 140°, with a clearance angle of 10°. Thin the webb to about 1/3 the thickness of a standared drill.

Welding
N-155 can be welded by metallic-arc, inert-gas-shielded arc, and solid-phase pressure welding methods.


Corrosion Resistance

In the solution-heat-treated condition it has about the same resistance to nitric acid as does stainless steel. At room temperature it has better resistance than stainless steel to weak solutions of sulfuric and hydrochloric acids.


Typical Mechanical Properties

Tensile Properties
Solution Treated 2150°F (1177°C), air cooled.

Test
Temperature

Tensile
Strength

Yield Strength
0.2% Offset

%
Elongation
in 2"

%
Reduction
of Area

°F

°C

ksi

MPa

ksi

MPa

Room
1000
1200
1400
1600
1800
2000

Room
538
649
760
871
982
1093

118
93
80
60
38
19
10

314
641
552
414
262
131
69

59
44
42
38
26
18
--

407
303
290
262
179
124
--

40
37
35
35
37
38
45

50
48
47
42
42
50
60

Stress Rupture Properties
Solution Treated 2200°F (1204°C), 1 hour, water quenched, + aged 16 hours 1400°F (760°C), air cooled.

Test
Temperature

Stress for Rupture in

°F

°C

10 Hours

100 Hours

1000 Hours

ksi

MPa

ksi

MPa

ksi

MPa

1200
1350
1500
1650

649
732
816
899

65
38
26
18

448
262
179
124

52
30
18
10

359
207
124
69

38
23
14
7

262
159
97
48

Multimet (N-155) - Current Inventory Stock

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