Non-magnetic high strength drill collar
Non-magnetic drill collars are made of low-carbon high-chromium manganese alloy steel, refined through strict chemical composition control, and specially forged. They have high-strength mechanical properties and low magnetic permeability, as well as excellent resistance to intergranular corrosion cracking and resistance to Abrasive. . Non-magnetic drill collars are used with MWD and LWD in directional drilling applications to allow magnetic measurements of well trajectories using instruments within the drill string. A magnetic measuring device (MWD) works in the hole of a non-magnetic drill collar and can measure the Earth's magnetic field without magnetic interference. The measuring instruments are isolated from magnetic interference caused by BHA and steel components in the drill pipe.
Chemical composition
|
Grade
|
Chemical composition and its content %
|
|
C
|
Si
|
Cr
|
Mn
|
Ni
|
Mo
|
N
|
|
W-1
|
≤0. 08
|
≤ 0.8
|
13. 5 ～
16.5
|
1 6.0
~
18.5
|
1.0 ～3.0
|
0. 4 0
~
0. 85
|
0.2 5
~
0. 40
|
|
W-2
|
≤ 0.0 3
|
≤ 0.8
|
1 3 ～
1 6
|
18.5
~
2 2 .0
|
1.0 ～3.0
|
0.4 ～0.80
|
0. 3 0
~
0. 45
|
|
W-3
|
≤ 0.0 3
|
≤ 0.8
|
16.5 ～18.5
|
18.5
~
2 2 .0
|
1.0 ～3.0
|
0.4 ～0.80
|
0. 50
~
0. 80
|
Mechanical properties
|
Grade
|
Outer diameter range
|
Yield Strength
|
tensile strength
|
Elongation A
%
|
Charpy impact work
|
Hardness ( HB )
|
|
㎜
|
MPa
|
ksi
|
MPa
|
ksi
|
21℃
|
-25°C
|
|
W-1
|
79.4 -174.6
|
≥758
|
≥110
|
≥ 827
|
≥ 120
|
≥2 0
|
≥ 85
|
≥ 40
|
2 85 - 400
|
|
177.8-279.4
|
≥6 89
|
≥100
|
≥ 758
|
≥ 110
|
|
W-2
|
79.4 -174.6
|
≥827
|
≥120
|
≥896
|
≥130
|
≥25
|
≥ 1 50
|
≥ 40
|
285-365
|
|
177.8-279.4
|
≥758
|
≥110
|
|
W-3
|
79.4 -174.6
|
≥965
|
≥140
|
≥1034
|
≥150
|
≥20
|
≥ 100
|
≥ 40
|
300-400
|
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