LC:
That is a standard Mil. 1595 welder performance qualification test used by most companies. 718 is very common in the aerospace industry, but have welded many other Inconel alloys. Usually companies have you run SS, Inco and aluminum - T, lap and butt joints on thick to thin materials.
My suggestions:
TECHNIQUE
1.) Use .035 filler rod. (The .045 can cool down or "chill" the weld when adding relatively large diameter filler metal on relatively thin material typically resulting in incomplete fusion. Think about it, the .045 is thicker than the thinner part joined...)
2.) I would not use the pulser on the Syncrowave. (I have taken this test everytime I started at a new company, and also had to retest every 6 months. Never had to pulse the thin Inco. Could be the reason for failing unless the company or WPS required pulsing the current.)
3.) Do NOT pump the pedal. (For the same reason I would not pulse the current.)
4.) Try fusing the joint first (yes the T) and then run a second pass with filler metal. You can use small tack welds at the start/stop points and they help initiate and terminate the initial autogenuos weld pass. (I have used this technique often on all 3 of the materials mentioned previously and never had any problems passing tests. A very steady travel speed is required and set the machine where the pedal is almost hits the stop. This will help to prevent blowing through the thin piece.)
5.) Direct the arc at the thicker piece washing the molten metal down onto the thinner part. (This action minimizes heat at the thinner part. This is performed with minimal torch oscillation as possible. Large weaving action will typically result in overheating the thinner part and the entire joint.)
6.) Joint fit-up is critical. 0 root opening. (Keep root opening as tight as possible during tack welding. This can make or break the test.)
7.) Slow arc travel speeds will overheat the entire test coupon. (Maintain a steady, continuous travel speed. This is completely dependant on your skill level. 4 -6 ipm should be about right depending on amperage.)
PREPARATION
8.) Wire brush weld areas just before the test and wipe with a clean, dry rag. (Do not use any chemical cleaning unless the parts have oil present. Clean the ink with the material spec. from the weld areas, front and back side of the joint. Also, wire brush the joint after tack welding and blow off the black soot. If you have to use solvents, make the dry rag the final cleaning process. Don't forget to wipe down the filler rod as well. Use a clean pair of gloves.)
9.) I usually use a #9 lense for materials that thin. Always show up for a test with a clean filter and protective plates in your hood. (This will increase your visibility, particularly on this type and thickness of material. I also use the "gold" lenses.)
10.) Clamp the parts to the bench, use chill bars if you have them. (This will help maintain root opening, keep the joint cool and minimize warpage during welding.)
COMMENTS
a.) I have taken this test without the "newer" generation of power supplies like the old Miller AB/BP's, Lincoln Idealarc Tig 300's, etc. without any problems. On the other hand have done it with an Aerowave or Squarewave Tig. It's the driver, not the car that wins the race (or in your case - who passes the test.)
b.) You probably need some practice, try to find a shop, school, tech. or vocational center where you can get some trigger time. Check around local precision sheet metal shops for scrap materials.
c.) Good Luck.
