orbital welding development - indico...started orbital welding in 2007 with the design methodology...
TRANSCRIPT
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ATLAS Upgrade Meeting
LBNL Sept 6th 2012
Richard French, Hector Marin-Reyes, Simon Dixon, Paul Kemp-Russell
The University of Sheffield
Martin Gibson, John Matheson, John Hill, John Noviss – RAL Ian Mercer - Lancaster
Orbital Welding Development
Started orbital welding in 2007 with the design methodology of:
• 100% reliable connector-less system.
• The tube will be galvanically more stable than the parts joined to it (e.g. grounding,
supports).
• The exceptions are joints, seals and connectors, these will have the same electro-
potential as the tube.
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Step back and sanity check?
Correct technology/materials?
Tube material, diameter, wall thickness, equipment portability are all obvious factors of which
joining method to adopt. There are hundreds of subtle influences that blur these definitions.
• Assuming ideal tube is no longer 316L stainless steel of ~200um wall > Now CP2 Ti, 125um wall
or thinner would I choose TIG orbital welding again without our knowledge of this technique?
• On paper the equipment specifications say no – nothing other than laser, EB, microplasma
diffusion bonding or brazing should work reliably at this wall thickness to make a welded
joint in CP2 Ti. Non-specialist “experts” would also suggest no.
• IGNORE SPECS – TIG WORKS WELL & IS PROVEN WITH HIGH REPEATABILITY as a
result of the last 6 years R&D and work with specialists in industry.
• I’ve learnt a significant amount about joining process for both 316L and CP2 Ti materials.
• Get the material right - the joining process follows naturally.
• Get the process correct and you have highly repeatable joint. • 6 years of materials development and refinement to make 2 bullet points!
TITANIUM DEVELOPMENTS
Assuming we are still on the correct side of sane…………
Achieving the correct material to work with in the first place.
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Oxidation of the Ti tubes - complete Removal investigated through wet and dry etchants
Dry etchants “Fun stuff”
Plasma cleaning of ends – Looks like this might
work, on short samples a reasonable result is achieved.
For the full circuit mods to the plasma cleaning machine
are required for a UHV seal to the tube.
Shot blasting with glass bead – Works fine but
requires very careful cleaning.
NONE APPLICABLE TO IN-SITU REPAIR (Scotchbrite)
Attempting to remove this HN03:HF dilute
HN03:HF
concentrate
Wet etchants “Nasty Chemistry”
HF based solutions and trials carried
out by,
Martin Wilson – STFC. Repeat/refine
Swantek – Jerry Lancaster. fin
HTT/ Anipol?NDT ltd. fin
Tube developments
• Need to begin pressure drop measurement component manufacture for
realistic results of mass flow etc to refine tube dimensions (ex & cap).
• 6Al4V Ti tube procured for alternative weld trials (is a better material all round)
but impossible to obtain stock in our small dimensions because of low volume
required. Could be made if we know a final quantity but our consumption is
likely still to be too low. Will continue to gather joining data as will be done and
published – an ideal but maybe not realistic
• GETTING A LEAK TIGHT SEAL ON ODD SIZED TUBE FOR TESTING IS A
PAIN IN THE A##. Everything is custom! Still a bad idea. 2 - 2.5mm OD please!
• Can only manufacture in 3m lengths due to EU cleaning chemical rules – working on
special dispensation but will need assistance as not much information available.
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CP2 Ti well proven and now established in use, oxide
issues solved in production using chemical etch
solution (pickling) and cleaning process ok and
proven, inspected & tested at CERN.
Now need final CT images (125um wall) and
evaluation from NAMTEC (freebie) to finalise
reporting. # Still not made many items in this material
Exhaust dimensions or on-Stave cooling tube
guessed> 2.175 OD x 0.125mm wall (CP2 Ti), shared
by IBL/PIXEL = sharing statistics and reporting. 50um image of tube end – small edge defects
Ti tube capillaries
• Capillaries – diameters and wall thicknesses now being prototyped. Initial
problems, 3m length, 150um wall was difficult to get round (stock sizes).
• Current capillary dimensions on offer (easy as drawn from stock) • MINIMUM BORE 0.3mm, MINIMUM WALL 0.150mm, MAXIMUM LENGTH 3000mm
1.2mm OD x 0.90mm ID x 3000mm
0.80mm OD x 0.50mm ID x3000mm
0.60mm OD x 0.30 ID x 3000mm
• Prototype capillary tubing fresh from the mill has now reduced wall to
• 0.750mm OD x 0.490mm ID x 0.1300mm Wall.
• 0.670mm OD x 0.405mm ID x 0.1325mm Wall.
• 0.595mm OD x 0.330mm ID x 0.1325mm Wall.
• 130um is about as low as sensible to pass pressure testing with headroom – we need good old
fashioned measurements now to determine the ID.
• 0.330mm ID is the smallest ID possible using this manufacturing process and UK factories.
• Larger ID’s than 0.5mm possible through to 0.9mm ID.
• Real testing is needed to enable further refinement, but it’s a start………..
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AIMING TO REDUCE MASS OF WALL
TO 0.125mm. Unlikely to be lower!
Tube stock availability & lead time
Production
Sample
Material OD mm ID mm Wall um length m Stock Due
Offcut
Qty Qty P/S/O
CP2 Ti 3.175 2.775 200 2.2m 22 P
CP2 Ti 2.275 2.025 125 3.0m 2 50 P
CP2 Ti 2.275 1.995 140 3.0m 18
CP2 Ti 1.775 1.525 125 3.0m 8
CP2 Ti 1.200 0.400 200 3.0m 6 P
CP2 Ti 1.200 0.900 150 0.6m 4 17 S
CP2 Ti 1.000 0.450 275 3.0m 2 P
CP2 Ti 0.900 0.360 270 3.0m 2 P
CP2 Ti 0.800 0.500 150 3.0m 18 P
CP2 Ti 0.750 0.490 130 0.6m 6 S
CP2 Ti 0.670 0.405 132.5 0.6m 6 S
CP2 Ti 0.595 0.330 132.5 0.6m 6 S
316L SS 3.175 220 5.0m 14 P
316L SS 3.175 220 1.8m 5 O
316L SS 3.175 140 2.7m 18 P
316L SS 3.175 220 1.8m 4 O
316L SS 3.175 750 2.0m 4 S
316L SS 2.000 140 2.0m 53 P
Aluminium 3.175 360 5.0m 32 P
Aluminium 3.175 660 5.0m 74 P
Aluminium 2.480 660 3.0m 69 P
Aluminium 4.760 340 2.5m 69 P
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• Capillaries had too much mass in
tube wall for optimal xo performance.
• Looking at max burst pressure v watt
thickness but large manufacturing
constraint as stock sizes dictating
final drawn size of ~130um wall
• Can only purchase as international
community to persuade Sandvik to
supply stock in small enough
volume. ~0.25 Tons.
• I still doubt that we can achieve
MOQ collectively so a rethink is
needed.
• Need to finalise a suitable joining
solution as EU REACH preventing
production longer than 3m – check if
international shipping dispenses
company from regs and store tube at
CERN? VAT?
PEEK capillaries 8
This is not a serious proposal! Ti production currently limited to 3m lengths
10m PEEK capillaries purchased for fun with ingenious finger tight 500bar connectors
• PEEK (polyetheretherketone) finger tight
fitting are convenient, inert, and bio-
compatible.
• 1/16 inch O.D. PEEK, stainless steel,
titanium, Tefzel, or PTFE tubing.
• Compatible with most solvents (not
concentrated sulfuric and nitric acids),
• PEEK ferrules do not permanently lock
into place on the tubing.
OD ID
360 µm 75 µm
1/32" 0.13 mm
1/16" 0.064 mm
OD ID
1/8” 75 µm
1/8”" 1.59mm
1/8" 2.0mm
Orbital TIG joint repeatability • CP2 Titanium1/8”OD x 0.20mm wall
• 1042 repetitive welds
• First 20 welds suffered from same lack of refinement as 316L process.
• Testing at CERN for random batch samples – shipped.
• OXIDE was a problem specific to this batch of Ti tubes only.
• Regular cleaning is increasing repeatability.
• More attention is paid to the joint preparation. And electrode.
• WPS being written (best practice)
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•The process is highly repeatable for both materials (316L & CP2 Ti) and now highly optimised. •I need to check this again with a number of fixed tubes representing detector service connections then repeat the process for the CP2 Ti 2.275mm OD x 120um wall when happier with the weld itself.
•Weld head angle. Electrode start position. Clearance for weld head •Internal gas purge pressure may be the tricky item to manage correctly during installation in the cryostat.
CP2 Ti weld joint
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– Flare one end of the tube to bring extra material into the overlapped joint. = 120μm + 120μm give a bulbous weld bead (now controlled to outside of tube by altering angle and depth of flaring tool)
Welded joint wall of ~220um wall at highest measured point
= straight tube flared tube insert
weld
~60μm
Welding of CP2 Titanium 120μm wall tube
First butt weld joint in 2.275mm CP2 Ti – pin hole every time.
– Can successfully join the 2.275mm OD x 120μm tube with orbital welding using the above process. Initial NDT results are underway (x-ray). Data returned (x-ray only) and have refined inclusions by
– better cleaning methods.
– This can be refined much further as not happy with visual results. ON THE LIMIT OF THE MACHINE
– Gas purge issue is due to custom fittings not sealing correctly on tube OD. Refined but not fantastic.
– Thrown fittings away and use soft Si tube (gas contamination)
Best welded joint to date using new tooling to
create sleeve joint. Still have a indentation
from post weld cooling [pressure or
cleanliness]
Will now start high repeatability trials with this material. 1000 samples (Ti shortage)
Welding system evaluation
• From my 2007 market survey, the Swagelok M200 TIG Orbital
welding system was the best priced system:
• CHEAP BY COMPARISON with other systems.
• EASY TO USE software removes operator knowledge
• WORKED OK FOR BASELINE 316L TUBE
• SERVICEABLE & SUPPORTED
• Has broken once, we’ve blown it up once or twice.
• Original system at Sheffield working fine
• 2nd System based at RAL.
• CAN NOT WELD 125um CP2 Ti
• FAILS TO WELD 180um wall tube.
• Weld heads all need to be modified to work well.
• Software all needed serious messing with.
• Effort v cost = not so good.
• Once the Ti wall went to 125um it caused me problems
• With enough time – most things work in the end.
• Biggest issue is high powered arc starting AV causing
potential issues for damage to electronics
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Swagelok M200 COTTS
Sheffield micro-weld head
Future plans for M200 development 12
• Weld head mods at Sheffield – have tried UHP small
weld head on loan from manufacturer. Have
constructed digital IO to analogue module to interface
to M200, unsure if was sensible use of effort as
virtually removes all M200 useful functionality.
• Modified version of the smaller scissor jawed weld
head from Swagelok is working well but needs further
refinement for joining 125um CP2 Ti.
• Electronics damage – slowly understanding more with
the system outputs and quirks, producing a best
practice guide to avoid majority of misfires.
• Reprogramming the system outputs (altering M200
welding software) for lower initial start arc – trade off
with arc ramp down – may be a waste of time but
worth a try.
• Adding grounding system to drop initial arc start
voltage – proving problematic so again, firmware
needs altering inside machine to allow arc to start
• Keep popping bits of the machine but it is easy to
repair and quite robust.
• Weld head internal temperature measurement is
in progress.
• Set up under construction for use with Tim’s
FEIR camera. Tech effort dependent.
• LASER WELDING – still on going investigations
from Ian Mercer, we did expect some delay from
SPI before final ideas placed on paper.
Hopefully news soon.
Ultra pure gas purge system
Understanding system performance
• Getting to grips with the M200 quirks.
• Misfires mainly caused by bad practice, poor joint alignment and
laziness. Correct procedure does solve this.
• Occasionally there is a weird event.
1000 welds on identical CP2 Ti stalks has seen 3 misfires = 3 failed joints. 1000+ welds on 316L tube has seen 5 misfires = 5 failed joints.
WHY?Tmperature alters gas pressure so need to adjust as lab warms up
RH should not affect closed chamber welds – measured, undecided as low stats
• We have no real way of measuring this. Right now I don’t believe the
OSD/GUI showing A/V of the weld = RMS + fudge factor.
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• SO- measurements needed – HOW?
• Looks nasty on first investigation but possible.
• Swaglok M200 has reverse engineering protection
in the system – connection of scopes and probes
etc cause misfire or failure to start weld procedure.
• It pretty simple in reality so we’ve figured out how to
get round this & can now take
measurements…………….. But before this……..
We made something new
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New welding system development
• Over the past 5 years in conjunction with our industrial partner Sheffield has
developed an fully automatic TIG welding system that produces accurate low
current narrow bead welds sourced from our partners aerospace joining
knowledge. It was obvious that nothing like this was commercially available.
• From the use of high frequency pulsing interposed within the pulsed weld current
gives the system its unique characteristic and is capable of joining two razor blade
edges together without distortion.
• The benefit of this technique is that increased arc force or penetration is achieved
with a lower input current which is crucial to thin wall Ti tube welding by allowing
for improved heat management on critical welds whist still attaining full
penetration.
• Has additional grounding to prevent
high arc start voltages through work piece
• Production version fully tested in Sheffield
available to ATLAS Upgrade for R&D.
• Looks to be capable of joining >125 um Ti using minimal power
– how thin? No idea at all (yet)
• ~0.3A, 30v on 250um CP2 Ti tube (automatic weld)
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16 Waveform arc v profile
PLEASE DO NOT REPRODUCE
System Details
• Initial Current 0.1 – 60 Amps
• Upslope time 0.0 – 20 Seconds
• Downslope time 0.0 – 20 Seconds
• Finish Current 0.1 – 60 Amps
• Finish time 0.0 – 25 Seconds
• Pre purge gas 0.0 – 100 Seconds
• Post purge gas 0.0 – 100 Seconds
• Main Current 0.1 – 60 Amps
• Background Current 0.1 – 60 Amps
• Main time 0.01- 5 Seconds
• Background time 0.01- 5 Seconds
• InterPulse Current 0.0 – 60 Amps
• Time per level 0.01- 99.9 Seconds
• Supply 230Volts 13 Amps 50Hz
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2.275mm OD tube weld cassette &
head with arc start grounding
Current set up in old lab, 3 TIG weld
systems 2 auto, 1 manual.
First weld set to offer the ability to weld single
crystal and difficult to weld alloys such as Inconel
738, 713, MAR-M 247, PK33 and Titanium without
a chamber or trailing gas shield.
Pulsing switched off
60 Amps at 14 Volts
(10 minutes welding 5 minutes cooling)
Pulsing switched on
50 Amps (60 A Main, 40A Background)
(10 minutes welding 1 minute cooling)
50 Amp Auto TIG version
(130 Amp too big for ATU)
Weld head 18
• Set up of electrode distance with
shim – needs refining
• Additional clamp for grounding
during arc start
• Remember start position and
direction
19 New system programming/test
2 years work in 6 hours!
Joints made with 0.4A & ~14v – no pulsing
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Weld Parameter Sheet
Parameters Values Joint type Tube-Tube, Tube,rod?
Material Ti, SS?
Diameter (mm)
Wall thickness (mm)
Tube length (mm)
Electrode Gap/Arc Gap/Set
(mm)
Electrode diameter (mm)
Electrode type 2% Th02, 2% La02?
Electrode length (mm)
Electrode Angle (deg)
Electrode Usage New, # Welds?
Tip Angle
Weld Head Orbit, Manual (turntable)?
Levels 1, 2,..?
• By simplifying the weld build up as
individual parameters, we can make
accurate reproducible joints.
• This approach is essential to automatic
welding
Generic weld system measurements
• Initial set up (principle so may refine)
• Torch micro-positioner & rotary table
• Can enclose in environmental chamber to match head
conditions. FTIR window for arc profile
• Some nice shunts for both A/V (plug and play to USB
with some of our own software) monitoring both
positive & negative outputs (electrode negative TIG
system)
• Power analyser measuring consumed power at 4
points in the system, mains input, pre start cap, pre
main weld IC, ramping IC. Will refine as understood.
• Using timestamp and data values linked via pc to both
measurement systems we should see the variations.
• We will then induce failure to measure and understand
what happens.
• We can then plug in the separate work-piece ground
and remeasure.
• Doubles up to measure electrode tip angle effects on
arc profile and subsequent power / heat input to tube.
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Turntable Manual torch micro-
positioner & fast scope
USB shunts
22 System measurement schematic
Input measured by
power analyser
Output by shunts
Timestamp and data
collected together in
LabVIEW programme
NOT tried out in anger
23 System measurements
• Single & 3 phase measurement
• Input voltage/current measurement
• Output voltage/current measurement
• Triggers at arc start
• Configures to open and closed
chamber weld heads or torch
• Synchronised data taking
• Hopefully learn nothing nasty!
Electrodes for TIG • Will drive you crazy….
• Swagelok items have to achieve CE certification. They are not fantastic for our
use. Need to understand tip/length reproducibility v performance.
• Custom electrodes made in-house at Sheffield outperform standard items.
Measured by reduced heat damage, deeper penetration of weld = ~35% less arc
power needed – need to work out how to cut tungsten to length accurately
without shattering electrode (causes premature wear / arc failures)
• Struggling for “clean” space – electrode prep contaminates area and reduces
weld performance. New lab taking time – refurbishment very slow.
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Tube/Electrode preparation area
• Current issues are debris contamination so need
some form of extraction – building does not
permit ventilation to outside world (Dyson?)
• Should store electrodes dry – drawers needed
• Bake out before use – oven?
• Separate grinding machines (or wheels) for
different materials – final choice = 1 wheel only
• Tube cutting proving laborious
• Tube facing tool performance satisfactory
• TOO MUCH STUFF FOR ONE PLACE
TIG grinder (wet)
Tube cutter
Tube facing
Decision time
• Theoretically there is only one of me, my time is split many
ways and I need to be more efficient.
• Assuming that 125um wall tube is desirable I’d sooner put effort into
new system testing and give up with pushing the M200 past its limits
and use this for tube wall >200um (services).
• I reckon we have ~50 separate measurements to make for each weld
to fully quantify and understand each.
• I’ve not made the time to document this work but have reasonable
notes. I’m in danger of forgetting as pace picks up.
• Odd OD’s cause huge tooling costs in fittings, weld heads etc.
• Pressure drop work is now ~ 1 year behind where we wanted
to be.
• We have many of the components but not enough to move forwards to
allow us to decide on tube ID’s (EX &Cap).
• Laser welding has gone very quiet – needs a push.
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Next 12 months overview Assuming we have minimal decisions made so rather vague or exceptionally obvious
• Stave, Stavelet cooling circuits
• Re-stock of cooling circuits and stavelet circuits. Include pressure testing > DATABASE entry.
• Re-stocking of tube material and bending trials on capillary tubing
• Pressure drop measurements –
• Components part produced – design finalisation required
• CO2 plant booking expired. This area has stalled and we are in trouble here.
• TIG Orbital Welding.
• Reprogramming M200 and using grounding system from new system
• Gas purge over long distance and multiple manifold measurements/effects on weld quality.
• Measurements of electrode tip angle – arc gap and power v weld quality
• Finalised electrode – seeking mass production or tooling to make in house.
• Continuing to refine Swagelok weld head for heat sinking and improved tube alignment.
• Bring online the InterPulse system and test on 2.275mm OD 125um wall CP2 Ti.
• Laser welding
• Hopefully news soon.
• Material reduction
• Changing bulbous sleeve joint to butt weld on 125um tube with tooling from PIPE ltd.
• Reducing mass in capillary tube wall – production limits.
• Fittings
• Vac brazed stubs full statistical trial.
• CP2 ti fittings – material sourced from Sandvik. Need to check cost out v custom fitting from Swagelok or Fti plus the
effort put in at QMUL.
• Re-manufacture of 6LV VCR thin wall fittings as run out.
• Thermal shock etc in the pipe line at some point – hardware almost completed at RAL.
• Burst testing of circuits to see where calculated headroom is v actual – mass reduction maybe.
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ADDITIONAL INFORMATION Alternative joining technique Vacuum Brazing of CP2 Ti to 316L Stave 250 drawings of cooling tubes at z=~1.3m
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• Overview • Stainless Steel to Titanium joining (temp connection)
• Copper to Titanium (pressure drop measurements)
ATLAS Upgrade dissimilar metal joining activities
Richard French, Paul Kemp-Russell: Sheffield Keith Birmingham: Aerobraze Europe Neil Austin: VBC Group Ltd (brazing division) Trevor Smith: Firmachrome Ltd Peter Cookson: Bodycote
Connectors
• Swagelok VCR in 316L works well as temporary fitting. Used 316L weld on
VCR either with a TIG weld or Vac Brazed joint.
• Mass of nut is an issue, also nuts are sliver plated inside to prevent
galling which has proved problematic for vac brazing.
• LOW mass fittings – VCR in CP2 Ti could be possible, can only find
reasonable stock in Grade9 Ti to produce. QMUL CNC? Units of
production too low for Swaglok MOQ
• Vac brazed stubs work well – need statistics
• Ideally remove the stub preferring tube-tube joint for low mass and
increased reliability - relatively easy to do with a sleeve jointed TIG weld
(common in nuclear reactors etc) – not ideal for dissimilar material joining
• Can vac braze 316L stainless to CP2, Grade 9 and 6Al4V Ti without
issues (other than getting the final ones back).
• Vac brazing ceramic to Ti & 316L next (ideally write up so far before this)
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Stainless VCR connector to Ti tube Used to make temporary test fitting stubs for cooling circuits…………
Method A = cheap idea
• Electroless Nickel Plating. • Electroless Nickel coating is an alloy of nickel and
phosphorous. Ability to work to close tolerances
without post-plating grinding, whilst holding the
original surface finish.
• Electroless Nickel can improve corrosion resistance,
wear resistance, lubricity, solderability or be used to
rectify and recover close tolerance undersize parts.
• The big advantage of elecroless (chemical) plating
over electrolytic plating is it will adhere to Titanium,
in a very controlled manner. We do not need to
plate the entire circuit, just local areas as wherever
the solution touches it will plate.
Method B = proven but expensive
• Vacuum Brazing using an
aerospace proven method • Using a silver copper eutectic braze alloy, coat the Ti
with the alloy, assemble the Stainless VCR fitting to the
tube (post electro-polishing) and place in furnace at a
lower temperature somewhere around 850°C. • http://www.vbcgroup.com/focus/Brazing-Division/Brazing-Alloy-selection-tables/BrazePrecious.htm
• Excellent joint, clean and pressure handling proven up
to 250bar.
• 3.175mm Ti has heavy oxidisation that is proving
difficult to remove. This is needed for the Cusil alloy to
adhere to the Ti tube.
• Once tube is cleaned (glass bead blasting) good
adhesion is found.
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•Both methods are the “active” or direct joining of dissimilar materials with a braze filler metal
(BFM). This is ideal for Ti as the BFM forms a strong permanent joint with the base
materials.
•What we did not realise is that at certain temperatures the Ti can suddenly start taking on
alloying abilities with the BFM. This should not have happened when correctly controlled.
•Titanium is a strong oxygen-getter, and thus will react with any oxygen that it can as it is
heated from room temperature up to brazing temperature, therefore, "reacting" too early.
•This is with free oxygen or water-vapor in the furnace atmosphere, or with metal-oxides on
the metal surfaces during heat-up (such as when the metals are not properly cleaned prior
to brazing), then the so called “brazing” (joining/bonding) of alloy-to-metal may be
completely prevented from happening.
Method A • During this process, the bonding was be
very successful but, the difference in the
thermal expansion between the 6LV
stainless steel – Nickel – Titanium which
it is being joined caused premature
cracking to develop in the brazed joint
upon cooling. If we did not see the cracks
at this stage they would present
themselves during subsequent use in
service.
• It is very important to try to match the
expansion characteristics of the metals to
filler to metal joint, so that huge stresses
in the joints are not built up.
• During the furnace cycle (1100C)
something really odd happened. High
temp was down to a miscommunication.
• The braze alloy has a initial melting temp
of around 400C. The furnace temp was in
the region of 1100C. Therefore we
managed to alloy Ni with Ti:
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Stress cracking CTE mismatched
Ni-Ti alloyed tube
As the Ti reaches 600C the oxygen in the Ti starts getting thirsty and in the resulting
exchange drags the Ni into the microstructure. As the assembly cools, it falls apart as
the CTE mismatch is beyond what the structure can cope with.
GOOD NEWS – we don’t necessarily need to vac braze all our components and can
do this with any induction furnace (have small tube furnace in lab ready). Ni plating
works fine so will drop the cost of the heater block joining for pressure drop work.
Method B = OK!
•For mechanical tolerance, achieve
a good push fit in the Ti tube to
VCR fitting. Micropolish fitting.
•Using Cusil braze alloy from VBC
simply clean components and plate
the Stainless Steel component.
•Mechanically clean Ti, chemically
clean the Ti, assemble components
and remember your nuts.
•Place in furnace at 850C and cycle
once allowing time to cool.
•Bingo – one joint.
•Items of weirdness to note:
•The VCR nut threads are silver
plated to prevent gauling during
assembly. This silver is reflowed
during the furnace cycle.
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NEW REFLOWED
1/8” Ti to VCR
1/8” Ti to VCR
2.275mm OD Ti to VCR
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What is length tube sticking out from
stave end? Universal decision for 250.
EOS – how does this shape up?
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Image of z=1.3 Stave end