Hey guys. I am bery new to the whole tig welding thing. Only made a few simple welds so far. I am just running a scratch start setup on my miller engine driven stick welder. I am going to need a lot more practice before i make any attempts at welding a rollcage or suspension components. My question is, is there anything wrong with using scratch start tig for welding chromoly and getting really nice quality welds? I read somewhere (not sure where) that scratch start tig makes a small brittle place that is subject to weld failure on some metals. Is that true? Any input on that is really appreciated.
Jason
- weldin mike 27
-
Weldmonger
-
Posts:
-
Joined:Fri Apr 01, 2011 10:59 pm
-
Location:Australia; Victoria
In my limited knowledge of the subject, it can be managed to very acceptable standards. If you are really worried about it, you can clamp a piece of copper to the job at the end and run off on to it. Also another trick is to start the weld on the tip of the filler touching the job and then twirl it ( a short length) like a drummer flipping sticks to the uncontaminated end.
Unless you are welding titanium do not worry about scratch start.
Thousands of welds are performed every day on site on stainless steels, cro-moly steels, nickel alloys using simple scratch start rigs. Many of these welds are then NDTed and even some DTed without any problems caused by the scratch start method.
There is no brittle area when scratch starting since you are melting over the place you touched to start the arc.
If you want to you can also flick the tungsten with the rod so you do not touch the base metal.
When you finish your weld increase your welding speed and then flick out the torch, then bring it back over the last welded area for a few seconds for the shield gas to protect it while it cools down.
Thousands of welds are performed every day on site on stainless steels, cro-moly steels, nickel alloys using simple scratch start rigs. Many of these welds are then NDTed and even some DTed without any problems caused by the scratch start method.
There is no brittle area when scratch starting since you are melting over the place you touched to start the arc.
If you want to you can also flick the tungsten with the rod so you do not touch the base metal.
When you finish your weld increase your welding speed and then flick out the torch, then bring it back over the last welded area for a few seconds for the shield gas to protect it while it cools down.
Just the kind of answers i was looking for. I did just watch one of jody's videos that has the trick with copper at the end of the weld to run onto like you said. I was unsure if that was acceptable for chromoly but that answers it. Thanks guys