Pinholes!!!

[Specialized37]

I'm using a Miller Axcess 300 DI interfaced to a Motoman Manipulator. I have 1 certain weld which is to be 25mm long and must have 20%min penetration to both parent materials which are high strength steel. This weld, at random, will have a pinhole at mid-length which doesn't appear to be gassification or arc explosion related. Travel speed, torch angle, travel angle, and weld parameters have all been "tinkered" with to try to solve this. Anyone have any others ideas??? 0.035 L6, 90/10argon/co2 I forgot to add that I am pulse welding.
Thanks

[diamondback]

If it is the repeatable as I am reading it into your question, place the arm in position and look for issues. I am not sure what you mean by L6. What are your parameters? What is the wire speed and arc adjust?

[Mec1]

Well first off i wouldent mess around too much with weld peramiters and travel angel If it only happens during this one particular 25m weld and your gas is correct I would look else where ground or operator error,how ever if I remember you said you were using L6 electrodes on high strength steel if you mean forgings or cast you could just be hitting sand pockets,arc out and repair just abought all you can do,now if outher than that say some 4140 ht or something like that maby try a different electode.I like to run la90 with a 90/10 personaly for most "high strength steels" but most of the time,I hate to tell ya,if your getting porosity
your not doing something right I.e.weld prep,pre heat to remove moisture or according weld procidures ya know . Well good luck

[turbo38t]

First bet is u have too much gas flow...other than that speed may be a hair fast. Is the steel new? It's not closing something up right? If you are sealing area off the last part of the weld will pop a hole. I'd also double check machine and make sure gun is all the way in the wire feeder and all mig parts r installed properly. Dave

Well first off i wouldent mess around too much with weld peramiters and travel angel If it only happens during this one particular 25m weld and your gas is correct I would look else where ground or operator error,how ever if I remember you said you were using L6 electrodes on high strength steel if you mean forgings or cast you could just be hitting sand pockets,arc out and repair just abought all you can do,now if outher than that say some 4140 ht or something like that maby try a different electode.I like to run la90 with a 90/10 personaly for most "high strength steels" but most of the time,I hate to tell ya,if your getting porosity
your not doing something right I.e.weld prep,pre heat to remove moisture or according weld procidures ya know . Well good luck