1)Chemical analysis for titanium tube and copper bars
Nominal chemical composition
杂质Minor element，不大于 max
工业纯钛 Pure Ti
The requirement of Ti tube material incoming inspection (Cladded
material is tailor-made product):
As per Chinese executive standard standards GB/T3620 or GB/T15073, titanium tube is TA1 or TA2. And they must be supplied with inspection report and chemical analysis (Refer to Table 1). Internal and external surface check for the Titanium tubes must be done at the same time. Surface defects such as crack, peeling, small pits, Oxide layer, oil dirt, can be allowed.
Copper used for Ti/Cu clad is T2 or TU2 as Chinese standard GB/T5231-2001). And they also must be supplied with inspection report and chemical analysis (Refer to Table 2). After receiving certificate, our inspector will check copper bar one by one, including length, roundness. Length measure by tape and recorded the result: roundness shall be measured by micrometer and caliper with records. Roundness within +/- 0.1mm is qualified, otherwise unqualified.
2) Flattening test
Flattening test equipment is oil hydraulic press machine. Cut 20mm of Titanium tube end as sample to press. No crack is allowed in flattening test.
0.07 for TA1, TA2 and TA9-1.
3) Torsion test
The quality of clad materials can be demonstrated with a torsion test. During this test strips of the material are taken out of the bond zone and twisted around their own axis several times. Clad materials of high quality must not demonstrate any separation of material after the test. Ti clad Cu is a metallurgical clad material of high quality where no impairment of the bonding materials will occur.
4) Thermal shock test
During the test process, a sample is annealed at a temperature of 520°C for a period of one hour and then subject to water quenching in a basin. This process is repeated up to forty times.
The tests of Ti/Cu Clad do not show any impairment regarding quality of the metallurgical bond.
As a result, the clad material bars can be directly coated with iridium, platinum or mixed oxides, since this process requires thermal treatment with many cycles at high temperatures.
5) Ultrasonic testing
The ultrasonic testing has been successfully used as a means of quality control in the recent years. Certain types of defects such as cracks or adhesion problems can be detected due to a higher efficiency of the testing techniques. UT test is required for every batch 5% for Ti-Cu clad rod. If any unacceptable defects are found during 5% UT, the extension of UT will be double as 10%; if more unacceptable defects are found during 10% UT, 100% UT will be mandatory for this batch. When the detection part bottom echo is clear, Ti and Cu composite plane has no echo display, this area is defined as quality. When detection area bottom echo diminish or disappear, and the according Ti/Cu composite interface echo is coming to display, this area shall be regarding unquality.
The so-called split test is a fast and proven method to an overall quality test.
The purpose of the split test is to try to separate the titanium layer from the copper core by using the lathe to mill the titanium layer of the sample bars from four sides. After separation, if color of copper surface is silvery white, without oxide layer, this will be regarded qualified,. If the color is dark brown, with oxide layer, this will be regarded unqualified,
i. Clean surface of bars with remover
ii. Spray penetrant on the bar surface and keep wet for 15 minutes.
iii. Wipe out excess penetrant on the surface, and then clean by cleaner or water.
iv. After surface drying, spray developer to the testing surface（spraying distance about 150-300mm）and keep wet for 15 minutes.