Newbie TIG Welder looking for some advice

I am a newbie TIG welder. I orginally learned to gas weld for the purpose of building an airplane. Most of the welding is in thin wall,
4130 steel tubing. After learning to gas weld, I then decided that I might like to do the welding with TIG and so took a 2 day TIG course about 6 months ago. I finally got a TIG welder and have been practicing for the past week. I'm sure I forgot most of what I learned in the 2 day course, but some of the welds look decent.
I have placed a few pictures of my welds at http://www.cmeek.net/welding
Here are the details: All flat plate welds are in 1/16in 4130. No cleaning of the metal was done as it was already pretty clean The tube welds are in 0.050 wall 4130 tubing. The tubing was cleaned using a wire wheel in my bench grinder followed by whiping with Acetone.
Tungsten: 2% thoriated, 1/16 in Cup: #6 Gas Lens Flow: 10-12 CFH Argon Rod: ER80S-D2, 1/16 in
Amperage: Butt Welds: 50 amps LapWeld1: 60 amps LapWeld2: 70 amps Fillet Weld: 80 amps TubeWelds: 50 amps
I know that the tube welds are not very pretty. I am having problems with blowing holes in the connecting tube. TubeWeld2 had several bad holes in it. I'm finding that TIG does not provide as much warning as gas does when it is about to make a hole.
So, what do you think? Any advice? Anything you see wrong that should be corrected? The tube welds seem to be more contaminated than the flat welds. Is there more cleaning that I need to be doing?
How come the butt and lap welds have little star patterns in the weld, and the fillet looks smooth? Is there anything wrong with either?
Thank you for any advice that you can give
Cam Meek
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Ref; TubeWeld1_Side2.jpg
The craters created at the end of your welds need to be filled in otherwise you have a very good place for cracks to initiate in the future. 50 amps on 0.050 tubing is a good setting for full penetration welds which is what you mentioned you are getting; you may want to try 40 or 45 amps.
The fillet weld size only need to be the same as the material thickness but in this case the 1/8" to 3/16" range would be easiest.
Ref; LapWeld2.jpg
Reduce your amperage here as well and the size of weld; need only be equal to 75% of the plate thickness or at most 1/6" leg lengths. The star effect appears to be stress lines originating from the center of the crater. Have to admit this is the first time I have seen this in a weld. Might be a problem of admixture (weld metal may be of a higher alloy content than it should be). Try an ER70S-2 or ER70S-6 too see if the problem occurs with a lower alloyed filler metal. The weld metal should pick up enough alloy to be in the same strength range as the 4130 in the normalized condition.
Are you allowing the weld puddle to solidify between each addition of filler metal?
Ref; FilletWeld.jpg
Looking pretty good; but you have too add a little more filler metal too the crater formed at the end of your weld. Also maintain your shielding gas for a few seconds after the welding current is stopped this will give the weld puddle time to cool enough so as not too form any porosity in the crater (stop).
Ref; TubeWeld2_Side1.jpg
Same lines on this weld as the lap welds. There will be someone in this group that has seen this before and found out what is causing it.
Here is a link too the lincoln site with a info on welding 4130 for aircraft. http://www.lincolnelectric.com/knowledge/articles/content/chrome-moly.asp
John Noon

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wrote:

No, I am keeping the puddle formed the whole time.
Thanks for all the advice
Cam
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Don't pull out too fast or you'll make what is called a fish eye, just gradually pull away wile moving forward and your puddle will taper off to a small point and your arc will stop.
B.H. http://www.totalprocessservice.com /
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