Weld Quality Question

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Hi;  I'm working to improve my MIG skills and wondered if you could evaluate these welds.  The square tubing is 2.5"x2.5"x3/16".  The plate is 4" square and 5/16" thick.  I had a 1/8" gap between the two pieces.  All welded areas were sanded clean with a flap wheel before welding.Any comments?  I got more splatter than I was expecting.  I'm welding with a 220V MIG welder, 25/75 Gas and 0.030 wire.  One thing that surprised me is I used less heat than I expected.  My welder is an old BetaMig so I don't know how many amps correspond to which setting but I started on 10 (Max) since the metal is relatively thick and burned holes through both pieces.  I found that setting the welder to "5" (which can't be more than 100 amps and is probably closer to 80 amps) was the best.  I think I got good penetration and the bottom of the 5/16" plate shows discoloration in the weld area.  Thanks;  Erik Attached Images
Reply:Looks pretty good to me a little undercut but not too bad. I would suggest angle it back a little more and move a little slower to build up more bead.
Reply:I don't know if your trying to create the stack of dimes look but try to master the smooth bead first.  Learn to wrap around your corners versus doing your start and stops there.  You don't need to have a gap on your welds and if your worried about penetration then just add a bevel to the square tube.  Discoloration should not be used as a guide for penetration, penetration and fusion are two different things, on doesn't guarante the other. Recreate the weld buy welding some 3/16" plate to 5/16" plate and weld a t-joint, then test with a BFH
Reply:JayO, can you please explain how penetration and fusion are two different things. To me it is one in the same, they both deal with the base metal and the filler metal. In order for something to penetrate there has to be fusion, and if there is fusion then there has to be penetration. sorry if this is a simple misunderstanding.
Reply:This goes back to when I was taking welding classes myself.  GMAW (short circuit mig) is known as a cold process and generally no having enough oomph to get solid good starts on welds.  I'm not saying it can't be done but in the right hands every process can be equal in strength.  Back to when going to school one of the test during the mig portion of the class was to weld some 3/16" thick pieces together in the vert up postion open root using a mig welder capable of putting out 300 plus amps.  Not one person would pass on the first try and some of these fellow students would put in some nice beads.  You could see on the back side that there was penetration as the root was filled and now wider then the original gap. SOme of these test plates were broken by throwing them to the floor and one was even broken by hand.  The first round of failure were examined and even the ones that were bent the edge of the bevel was still visible.  It wasn't until the teach showed us how to play with the settings that we started passing the test.
Reply:Jay, I guess that was an attempt to answer how penetration and fusion are two different things. I will say they are the same, and often used together, but more often then not they are confused, I suspect that this is the case here. I am not trying to flame you here, but one more thing to add it is kinda hard to determine lack of fusion with out testing either destructive or by x ray.
Reply:Thanks for the good comments.  I wasn't going for a stack of dimes result, rather I was trying to heat the bottom more than the square tube (since the tube is 1/8" thinner) by going in circles and spending more time on the bottom plate than on the tube.I really like the idea of welding around the corners, I'll do that next time.  I'll also slow down a bit to eliminate the undercut. Seems I'm always welding too fast!Regarding the discoloration on the bottom, in some of my early attempts I found I wasn't putting enough heat into the material which resulted in poor welds.  It seemed that welds which didn't get the metal hot enough to discolor the back side were not strong when I did destructive testing.  I don't know if it's true but it seems to me based on experimentation that if I don't get a pretty strong discoloration on the other side of the metal,  I didn't get the weld hot enough.  What's the correct way to determine if you got good fusion on a MIG weld?Thanks again;Erik
Reply:Erik- some things to consider about fusion in regards to your post these are some ideas that you can use to try and get proper fusion in your welds, I would also say that the welds look good for still being new to MIG. keep up the practice!Increase included angle of groove joint.Change the groove design to a 'J' or a 'U' type.Clean weld surfaces prior to welding.Maintain proper electrode position and current.Use correct manipulation techniques to melt the joint faces properly.
Reply:eriksalo - Are you right or left handed.  Opus
Reply:Originally Posted by eriksaloThanks for the good comments.  I wasn't going for a stack of dimes result, rather I was trying to heat the bottom more than the square tube (since the tube is 1/8" thinner) by going in circles and spending more time on the bottom plate than on the tube.I don't know about "circles", but weaving has worked for me.  And you're right, more time on the thicker pieceI really like the idea of welding around the corners, I'll do that next time.  I'll also slow down a bit to eliminate the undercut. Seems I'm always welding too fast!If you have to move too fast, is your heat too high?Regarding the discoloration on the bottom, in some of my early attempts I found I wasn't putting enough heat into the material which resulted in poor welds.  It seemed that welds which didn't get the metal hot enough to discolor the back side were not strong when I did destructive testing.  I don't know if it's true but it seems to me based on experimentation that if I don't get a pretty strong discoloration on the other side of the metal,  I didn't get the weld hot enough.  What's the correct way to determine if you got good fusion on a MIG weld?Destructive testing on scrap Thanks again;Erik
Reply:Hi All;Opus, I'm right handed.Regarding the other questions, I'm using solid wire, 0.030" diameter.  Wire speed is 350 ipm.  All weld surfaces were sanded to bright, shiny bare metal a few minutes before I did the weld.  Stickout is about 1/2".  Metal is new  steel.  Sounds like I should try turning the heat down.  I'll do that tomorrow on some test pieces, and slice them up to see how they look.  Will post some new pics and do a destructive test to see how strong the welds are.The
Reply:Hi, I would be more inclined to V the SHS tube rather than raise the tube up and it looks to me like your moving the torch a little erratically. You should be able to get rid of most of your splatter by tweaking your settings a bit on a piece of scrap first to find what works best. Each MIG welder is different and it takes a little while to work out what settings are best to use in which position on different sized steel. I usually try out a new welder first on lots of scrap of different thicknesses and combinations and write down the settings in a notepad which I keep near the welder for future reference, so that I don't have to constantly check and adjust. If you are working constantly with different sized steel you eventually get a range of settings which you can refer to  which will be pretty much in the ball park and might just require a little fine adjustment maybe in the speed of your movement to give you a acceptable weld.Hope this helps.Miller Auto Invision 456 + S-62 wire feederC6240B1 Gap bed lathe16 ft3 air compressor16 speed pedestal drillHafco BS-912 Bandsaw
Reply:Take a piece of scrap and run a bead with 1/2" stickout then run succesive beads shortening stickout by 1/16" with no other changes until about 3/16" stickout and inspect the difference.Millermatic 200Hobart Handler 120Victor O/A & Ramco BandsawLincoln 225 ACSnapOn AD HoodMiller XMT304/22AHypertherm Powermax 1650 G3Lincoln Idealarc DC600 w/Extreme 12 VSMiller Digital Elite "Joker"
Reply:mmchugh, I guess your right that fusion and penetration are not two totally separate things but more like components or characteristics of the weld . My example of the test plates that were done in school showed good penetration with both sides of the root fused together and the face of the weld also should good fusion.  These plates were then prepped to be tested and it wasn't until the bend test that the lack of fusion became visible . Looking at the coupons  you could clearly see the line (gap) between the bevel and weld.  It is hard to test for lack of fusion that is why I stated to recreate the weld or what a really ment was to recreate a portion of the weld and subject it to the BFH test.  If he were to be happy with results then he could use those setting to weld up the joints he was working on.  As one's experience grows then the need for testing goes down you just got to put in the time under the hood.
Reply:Originally Posted by Jay Ommchugh,  As one's experience grows then the need for testing goes down you just got to put in the time under the hood.