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Hardfacing
Alloys -
Hardfacing alloys may be categorised as
(i) Low alloy ferrous materials (total alloy content 2-12%)
(ii) High alloy ferrous materials (total alloy content 12-50%)
(iii) Nickel base alloys (e.g., Monel, Nichrome and Hastelloy)
(iv) Cobalt base alloys
(v) Copper base alloys
(vi) Stainless steels
(vii) Carbides.
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(i) Low alloy ferrous materials
Chemical composition of some alloys of this category:
| C |
Mn |
Si |
Cr |
Ni |
Mo |
W |
V |
B |
Total, % |
| 0.15 |
0.90 |
0.50 |
0.50 |
- |
0.30 |
- |
- |
- |
2.35 |
| 0.23 |
0.90 |
0.50 |
0.40 |
1.00 |
0.60 |
- |
- |
- |
3.63 |
| 0.50 |
0.80 |
0.30 |
1.00 |
- |
- |
|
0.20 |
- |
2.80 |
| 0.15 |
1.10 |
0.70 |
3.00 |
- |
0.90 |
|
- |
- |
5.85 |
| 0.30 |
1.70 |
1.20 |
6.00 |
- |
0.80 |
|
- |
- |
11.50 |
| 1.80 |
0.30 |
1.00 |
5.40 |
- |
- |
|
- |
0.50 |
9.00 |
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Field of Application and characteristics
These alloys are often used as build-up materials for support of harder, more highly alloyed hardfacing materials. These alloys possess the greatest shock resistance of all hard facing alloys except the austenitic manganese steels and have better wear resistance than low carbon and medium carbon steel, which is the base metal to which they are usually applied.
These alloys are comparatively less expensive and are extensively used where machinability is necessary and only moderate improvement over the wear properties of the base metal is required.
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(ii) High alloy ferrous materials
Chemical composition of some alloys of this category:
| Type |
C |
Mn |
Si |
Cr |
Ni |
Mo |
W |
V |
B |
Total, % |
| A1 |
0.40 |
0.40 |
3.80 |
16.50 |
- |
- |
- |
- |
- |
21.10 |
| |
0.50 |
0.90 |
1.10 |
5.60 |
5.40 |
- |
- |
- |
- |
13.50 |
| |
0.50 |
2.00 |
1.40 |
9.00 |
- |
1.80 |
- |
- |
- |
14.70 |
| |
0.20 |
- |
- |
5.00 |
- |
3.00 |
3.60 |
0.30 |
- |
12.10 |
| |
0.24 |
0.90 |
0.70 |
2.50 |
3.20 |
7.20 |
- |
- |
- |
14.74 |
| |
0.70 |
0.50 |
0.70 |
4.00 |
- |
7.30 |
1.80 |
1.10 |
- |
16.10 |
| A2 |
1.75 |
0.30 |
1.00 |
9.40 |
- |
- |
- |
0.20 |
- |
12.65 |
| |
2.00 |
0.60 |
1.50 |
9.00 |
- |
- |
- |
0.20 |
0.88 |
14.18 |
| |
3.50 |
1.50 |
1.50 |
16.00 |
- |
1.00 |
- |
- |
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23.50 |
| Type |
C |
Mn |
Si |
Cr |
Ni |
Mo |
V |
others |
Total, % |
| B |
0.80 |
- |
- |
4.00 |
- |
9.00 |
1.5 |
- |
15.30 |
| 1.40 |
- |
- |
4.10 |
- |
9.70 |
- |
1.4B |
16.60 |
| 3.75 |
1.00 |
1.00 |
- |
- |
10.00 |
- |
- |
15.75 |
| C |
0.70 |
14.00 |
0.90 |
- |
4.00 |
- |
- |
- |
19.60 |
| 0.75 |
14.60 |
0.70 |
- |
- |
0.80 |
- |
3.00Cu |
19.85 |
| D |
0.07 |
7.50 |
0.60 |
18.50 |
4.00 |
- |
- |
- |
30.67 |
| 0.40 |
14.00 |
0.50 |
14.50 |
1.00 |
1.70 |
0.60 |
- |
32.70 |
| 0.80 |
- |
- |
22.00 |
9.00 |
0.50 |
- |
- |
32.30 |
| 1.20 |
14.00 |
0.80 |
15.00 |
1.00 |
- |
- |
- |
32.00 |
| E |
1.75 |
1.00 |
1.50 |
30.00 |
3.00 |
1.50 |
- |
- |
38.75 |
| 2.50 |
1.00 |
0.80 |
25.00 |
- |
- |
- |
3.75Co & 0.55B |
33.60 |
| 2.00 |
2.20 |
2.30 |
23.50 |
- |
- |
- |
- |
30.00 |
| 4.00 |
- |
1.00 |
16.00 |
6.00 |
- |
0.5 |
- |
27.50 |
| 3.10 |
0.30 |
1.20 |
17.00 |
- |
16.00 |
1.9 |
- |
39.50 |
| 4.30 |
- |
- |
16.00 |
6.00 |
18.00 |
- |
1.00Ti |
35.30 |
| 5.80 |
0.50 |
1.50 |
22.00 |
- |
6.00 |
- |
4.00W |
39.80 |
| 2.30 |
- |
- |
16.00 |
6.00 |
- |
- |
20.00Co |
44.30 |
| 3.60 |
0.60 |
1.60 |
15.40 |
- |
3.10 |
- |
23.30Co |
47.60 |
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Characteristics
Alloys A1, A2 and B are more wear resistant, less shock resistant and more expensive than low alloy ferrous materials (Category - i). Alloys C and D are highly shock resistant, but have limited wear resistance unless subjected to work hardening. Alloys E are characterized by massive hyper-eutectic alloy carbides that impart wear resistance and some degree of resistance to heat and corrosion. However, they are most expensive as compared to alloys discussed before them.
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(iii) Nickel-base alloys
Chemical composition of some alloys of this category:
| C |
Mn |
Si |
Cr |
Ni |
Mo |
W |
Fe |
B |
Co, % |
| 0.25 |
0.8 |
0.8 |
27.00 |
2.75 |
5.00 |
- |
1.5 |
- |
Balance |
| 1.10 |
- |
- |
26.25 |
- |
- |
4.20 |
7.0 |
- |
Balance |
| 2.80 |
0.8 |
1.50 |
30.00 |
2.50 |
0.80 |
12.50 |
2.5 |
- |
Balance |
| 3.25 |
0.8 |
1.50 |
26.00 |
2.50 |
0.80 |
14.00 |
4.0 |
- |
Balance |
| 0.07 |
0.8 |
2.50 |
21.00 |
1.50 |
0.80 |
4.50 |
1.50 |
2.40 |
Balance |
Characteristics
The nickel base alloys are most effective for service involving both corrosion and wear. They are superior to other hard facing alloys where wear is caused by metal-to-metal contact, as in bearings. The nickel base alloys retain useful hardness up to about 650°C and resist oxidation at temperatures up to 870°C.
(iv)Cobalt-base alloys
Chemical composition of some alloys of this category:
| C |
Mn |
Si |
Cr |
Ni |
Mo |
W |
Fe |
B |
Co, % |
| 0.25 |
0.8 |
0.8 |
27.00 |
2.75 |
5.00 |
- |
1.5 |
- |
Balance |
| 1.10 |
- |
- |
26.25 |
- |
- |
4.20 |
7.0 |
- |
Balance |
| 2.80 |
0.8 |
1.50 |
30.00 |
2.50 |
0.80 |
12.50 |
2.5 |
- |
Balance |
| 3.25 |
0.8 |
1.50 |
26.00 |
2.50 |
0.80 |
14.00 |
4.0 |
- |
Balance |
0.07 |
0.8 |
2.50 |
21.00 |
1.50 |
0.80 |
4.50 |
1.50 |
2.40 |
Balance |
Characteristics
Cobalt base alloys are generally rated as the most versatile of the hard facing materials. They resist heat, abrasion, corrosion, impact, galling, oxidation, and thermal shock erosion and metal-to metal wear. Some of these alloys retain useful hardness up to 815°C and resist oxidation temperatures up to 1095°C.
(v) Copper-base alloys
| Serial number |
% Composition |
Ultimate Compression, list |
Average deposit hardness Brinell (a) |
Typical Applications |
| 1. |
A1 6-9
Cu Balance |
105.0 |
125(b)
85(c) |
Corrosion resistance
Soft bearing surfaces
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| 2. |
A1 9-11
Fe. 1.5 max
Cu Balance |
120.0 |
160(b)
119(c) |
Dissimilar metal joniing
Bearing surfaces corrosion resistance |
| 3. |
A1 10.25-11.75
Fe 3.0-5.0
Cu Balance |
130.5 |
207(b)
177(c) |
Bearing surfaces
Cavitation resistance |
| 4. |
A1 13.0-14.0
Fe 3.0-5.0
Cu Balance |
160.0 |
340(b)
260(c) |
Extreme bearing and Compression resistance, draw and forming dies. |
| 5. |
A1 7.0-8.0
Fe 2.0-4.0
Ni 1.5-3.0
Mn 11.0-14.0
Cu Balance |
135 |
217(b)
185(c) |
Corrosion, erosion and cavitation resistance,ship propeller repairs. |
(vi) Stainless steels
| Serial number |
Type |
Characteristics |
Applications |
| 1 |
High C-Ni-Cr stainless type |
Oxidation and hot wear resistant |
Furnace parts |
| 2 |
Low C-Ni-Cr stainless type |
Oxidation and corrosion resistance |
Corrosion resistant surfacing of large tanks |
| 3 |
13% Mn-Ni-Cr type |
High yield strength for austenitic types |
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(vii) Carbides
Hard granules of tungsten carbide are distributed in the metal matrix. Matrix metal may be iron, carbon steel, nickel base alloy, cobalt base alloy or bronze. The tungsten carbide materials provide maximum abrasion resistance under service conditions involving low or moderate impact. Successful applications are oil well rock drill bits and tool joints.
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