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Welding
of AA2219 Aluminium Alloy
WRI was entrusted with the task of developing welding procedure for the high strength
aluminum alloy AA2219. The
scope involved establishment of welding procedure for the aluminium alloy AA2219 (Al-Cu
Alloy) in heat-treated (T87 temper) condition using the TIG welding process in Direct
Current Straight Polarity (TIG, DCSP) mode in place of the AC TIG process which is usually
used to weld aluminum. The welding process was successfully established using a mechanized
welding
set-up for different welding speeds and heat input levels while  meeting the special
requirements of TIG welding of aluminium alloys in DCSP mode. 7mm thick AA2219 aluminum
alloy plates were successfully welded using square butt joint geometry in single pass with
feeding of 1.6mm dia filler wire and at d by the customer and the report was
accepted. |
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welding speeds of 350mm/min and
450mm/min. A narrow weld-bead width of about 10mm as shown in the photo-macro-graph, with
very good joint strength could be achieved. This is the first
time that this technology of DCSP TIG welding of AA2219 aluminum alloy has been
established in India. The work was appreciate |
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Resistance Seam
Welding Controller
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A special purpose cladding system has
been developed for internal stelliting of tubes and valves having small diameter bores
using MIG welding Process. Salient features of the machine include a special purpose
welding torch, a column mounted X-Y slides, a motorized torch holder and synergic MIG
welding power source. This system enables mechanised cladding of deep bores with
restricted axis in cylindrical sections resulting in excellent weld quality. |
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Metal Powder addition
in Tandem Submerged Arc |
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In Tandem Submerged Arc Welding the
arc cavity has excess heat energy which can be advantageously
utilized. The introduction of additional filler material in the form of metal powder
can lead to sustained increase in the
deposition rate resulting in reduced joint completion time. Further metal powder addition
to Tandem submerged arc welding reduces the depth of penetration and dilution by 20-30 %
which results in improved mechanical properties. A 60 % increase in productivity can be
achieved for the same energy input. Procedures have been established for addition of iron
powder for welding of mild steel. With the addition of metal powder having chemical
composition matching with that of the filler wires, this technique can be applied in
welding of offshore structures, shipbuilding and pipe welding. |
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Mechanised Stelliting
of OFE Seat Ring |
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Stelliting of OFE seat ring is done
manually employing gas stelliting and partly by plasma stelliting process. The manual
stelliting is a slow process and gives very low productivity and also quality problems.
The plasma stelliting though relatively fast, involves loss of stellite powder and over
heating of the components particularly the smaller diameter seat rings. The flux cored
stelliting process has been found to be good an alternative for this application. A
mechanised system consisting of welding positioner, oscillation unit and GMAW power source
has been developed. The mechanised flux cored stelliting process is found to provide
consistent quality and improved productivity of 5 to 10 times in OFE seat ring stelliting
application. |
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Repair of Inconel
Muffle of FHD Furnace |
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WRI was approached for repair of
muffle of FHD furnace. The muffle was fabricated out of inconel material (thickness 5 mm)
and of size 100 X 450 X 3300mm long. Some portion of the muffle (about one meter length)
got deformed during usage and is to be replaced by welding good portion from another
damaged muffle. The repaired muffle should be with minimum distortion and should be gas
leak tight for 2kg/cm2 pressure. The inner surface ofbottom portion and sides should be
flush ground.The bottom portion and sides of the muffle were welded by manual TIG process
with filler wire while top curved portion was welded by TIG / SMAW process at WRI meeting
the requirements on distortion and leak tightness |
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Repair of a cooler for
FHD sintering furnace |
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WRI was referred for repair of a
cooler for FHD sintering furnace, which had leakages at several locations. This Cooler was
used for cooling the sintered rods coming out of the furnace. The cooling tank was made up
of 5mm thick 316 type stainless steel. In-situ metallography was done on the material and
the cause of failure was assigned to thermal fatigue.
The Liquid Penetrant test was conducted to identify the
defects. The cooler was subjected to hydraulic test and leakage was found in many places.
The defective areas had limited access to repair welding. The repair welding was carried
out successfully using MMAW and TIG welding. |
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Low Cycle Fatigue
Test |
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Low Cycle load tests on butt joints
were carried out to qualify welding consumables. The tests were carried out at as low a
frequency of 0.5 Hz at specified stress range on full scale weld specimens up to fracture
or up to specified load cycles whichever was earlier both in air and saline water medium
using Instron 1276. The objective of the tests is to evaluate the fatigue performance of
the joints welded with different welding consumables supplied by different vendors.
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To carry out fatigue tests in saline water medium, a
suitable chamber was designed and fabricated at WRI which is to be leak-proof through out
the test. |
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Research & Development
