What do the people out there think of using LC72 wire electrode with the SAW process? I recently started a new job, and was kinda taken back be the fact they were using a flux-core wire with this process. It gets worse, they and I say they, because I haven't been here long enough to say we yet, are welding this type of combination, with a negative polarity. The joint is a double angle, double bevel groove weld, and they have a great deal of UT failures. Could The UT failures be atributed to the fact that they us the negative polarity, or is it something else? The failures are generally slag inclusions and some lack of fusion. I'm trying to get them to use or try, the positive electrode and solid wire, but have received a great deal of resistance, you know, "we have been doing it like this for years" type of responce. Then again, I may be all wet. Submerged arc welding, is welding under water right? LOL
Rick:
Good luck with the new job. I don't have any answers for you but I would like to know about the PQR/WPS? Does one exist? Are you (I say you, because you are there and therefore a part of the team from day one) straying from a developed WPS?
Regards, Donnie Mann
I don't know how they developed the PQR I don't have access to that. What we are welding is very large gears and the web is machined to the joint I discribed above. When we run the peramiters, is when we have the problem. We are stacking welds around the perimiter in the horizontal position. Another problem WE have, is overlap of the weld. I think because of the negative polarity, and position we are in, might be the cause of this. When we run positive, ther is no issue with the quality of the weld, and at negative is when all the issues appear.
Rick:
I know of a major US compnay that has been using LC 72 for welding up large turbine parts for many years, they also had a few problems along the way. What kind of flux are you using-Lincoln recommends 980. As far as slag inclusions, First I would check that the welders are really cleaning after they run a pass, then check you side wall to electode travel, I've seen times where you where actually undercutting the side wall and then trapping slag, but it was covered up as the weld cooled, this also could be your cause of the lack of fusion. Good luck
Greg
We are using the 980 flux
Get on the phone to the submerged arc consumables group at LE in Cleveland. Keep pestering for the right people and you'll get there.
My thought is that with negative polarity the heat energy is concentrated in the electrode side, rather than the work side and the penetration is relatively less and the weld metal build-up greater. This relative cooler weld metal mass/volume condition is occuring for your weld. Thicker, colder, weld metal means less time for slag to flux to the surface and an increase in the liklihood for cold lap or incomplete fusion, etc.
By Denni
Date 04-11-2006 16:27
Call Michael Flagg @ Lincoln 1-216-383-8847
