Hello diverdileo, the particular bead description that you have described and inquired about(if I understood correctly) shouldn't have an appreciable effect on weld integrity other than if the ripples were spaced so far apart that they were making the puddles have notches between them as the weld progressed. These notches could possibly be viewed as stress risers and pose a problem with cracking or other metallurgical issues. I just reread your questions/statements and would further comment regarding penetration/distortion, GTAW is rather unique from the standpoint that you have a number of variables that affect the finished weld deposit that other processes don't. One: you can either run a lot of amperage and move along quickly to achieve a particular weld bead width/height or you could run lesser amperage and travel more slowly, and yet, essentially still produce basically the same visual bead dimension. Throw filler metal addition into the mix and different styles/techniques and you could still produce similar visual results, yet considerably different metallurgical and physical bead/basemetal results(ie. penetration, stresses, weld interface, HAZ differences). I do somewhat agree that a dab vs. continuous(smooth) bead style may affect distortion and heat input, yet there are so many other variables that I wouldn't apply a blanket statement to one being better than the other. Different operators could likely use either method and still achieve completely acceptable results concerning distortion/heat input etc. I will be curious to see what others will have to say. If you could clarify your questions any, I believe that myself, as well as others, might better be able to answer. Best regards, Allan
We need alot more information from you.. As Allan mentioned, before a real authoratitive answer can come.
On carbon steels and stainless steels the "laywire" technique is for the most part equal mechanically to the dip technique.
The laywire is what you would refer to as the smooth appearance.. The dip technique would be the dimes. Always good to be aware of correct terms.
for lap joints and tee joints that are single pass and for many open root welds the lay wire technique is pretty common.. Pipe welders who produce open root welds on pipe use a technique called "walking the cup" the first passes on cup walked welds often use the lay wire technique in order to keep a controlled amount of filler in the joint.
The only time (other than cosmetics) that the dip technique *must* be used in order to get superior mechanical properties is with AC welding of alumninum and magnesium alloys... The lay wire technique defeats the *cleaning action* produced by the DCEP side of the AC cycle.
Still ... Without knowing exactly what your trying to accomplish.. it's difficult to say with authority if one technique is superior.
Remember all automated GTAW is done with a continue wire feed and will have a smooth bead appearance. Thus it is perfectly possible to do a wide array of welding with out the display of ripples.
to my knowledge there is no technical reason why one bead appearance is superior. I can think of a few specific cases where the engineer or shop experience may dictate that you don't want people to lay in wire or dab. I was personally taught to always dab, later on in pipe welding I would use the lay wire technique for fill passes where appearance wasn't critical.
I don't think it is appropriate to reject or hassle welders that meet all mechanical and NDT requirements for using a smoother bead appearance. unless the weld beads have a certain visual req.
Depending on the weld joint I would instruct my welders to either lay in the wire or dab. from a heat standpoint laying in wire usually cools the puddle more or limits penetration which usually explains the lack of fusion defects. The benefit is that it produces more fill or helps with excessive penetration.
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