The Move To
Copper-Nickel Tubing
Copper had been proved since the early days to have many good
attributes. It was easy to bend and had very high corrosion
resistance, but there was concern about its low
corrosion-fatigue strength. When copper-nickel was introduced,
it displayed corrosion resistance similar to copper, higher
general strength and better fatigue strength. Good formability
allows ease of flaring and bending, and although the metal cost
is greater than that of steel alternatives, copper-nickel is
very attractive in view of its extra life, trouble-free
installation and safety/reliability characteristics.
Properties of Copper-Nickel Brake Tubing
The copper-nickel alloy used for brake tubing typically
contains 10% nickel, with iron and manganese additions of 1.4%
and 0.8% respectively. The product conforms to ASTM B466
(American Society for Testing and Materials), which specifies
dimensions, tensile strength and yield strength. Formability and
internal cleanliness conform to specifications SAE J527, ASTM
A254 and SMMT C5B (Society of Motor Manufacturers and Traders).
Also, the alloy meets the requirements for pressure containment,
fabrication and corrosion resistance for ISO 4038 (International
Standards Organization) and SAE J1047.
The mechanical properties of alloy C70600 in comparison with
steel and copper are shown in
|
Dimension
Tolerance |
|
|
|
| Material |
Ultimate Tensile Strength1000
psi (MPa) |
Yield
Strength 0.5% Ext.under Load 1000 psi (MPa) |
YElongation % in 2
in. |
Fatigue Strength
(10x7 cycles) 1000 psi (MPa) |
Burst Pressure* 1000
psi (MPa) |
| Copper-brazed Steel |
48-55 (0.330-0.380) |
28-34 (0.190-0.235) |
30-40 |
30 (
0.210) |
19.5
(0.135) |
| C12200-Phosphorus deoxidized Copper |
32-38 (0.220-0.265) |
10-14 (0.070-0.100) |
45-60 |
10
(0.070) |
12 (
0.083) |
| C70600-Copper Nickel 90-10 |
48-54 (0.330-0.370) |
16-22 (0.110-0.150) |
40-55 |
15
(0.100) |
19 (
0.130) |
Alloy C70600 is normally supplied as redrawn tubing in the
annealed condition. The combination of strength and good
ductility give excellent formability.
As copper-nickel is softer than steel, it was first feared that
fretting might be a problem. Experience has shown this is not
the case.
Corrosion Resistance
For many years prior to its application as a brake tubing
material, alloy C70600 had been used in ships, power station
condensers and hydraulic lines on tankers, and had displayed
excellent resistance to saline conditions. Early tests revealed
that copper-nickel has almost the same resistance to burst
pressure as steel. In testing, however, when exposed to salt
spray over 180 days, steel's burst strength decreases
significantly. The copper alloy remains consistently resistant.
For tubes covered with a moist, salty mudpack for six months,
brazed steel was severely corroded resulting in perforation of
the tubing wall; whereas, only superficial general corrosion was
found on the copper-nickel tubing. ISO 4038 and SAE J1047
include a corrosion resistance requirement referring to ISO 3768
asking for a minimum burst pressure of 110 MPa after 96 hours in
neutral salt spray. Swedish requirements include a resistance at
least equal to 25µ of zinc. In all cases alloy C70600
easily exceeds the required corrosion resistance.
Copper-nickel brake tubing provides superior reliability and
assures both manufacturers and vehicle owners improved
durability for effective long-life functioning of the brake
system.
|
Copper-nickel
brake tubing provides superior reliability and assures both
manufacturers and vehicle owners improved durability for
effective long-life functioning of the brake system.Coils
Available in 5 mtr, 10 mtr & 15mtrs.