Thread: TIG Welding Cast Hollow Bar (CHB)

Is the Bar Cast Steel or Cast Iron.

Steel. I got it from offcuts galore. Machines like a dream but I wasnt sure if it was suitable for welding or not.

Is it a weld preped surface your attempting to weld too.

Yes, the CHB is straight off the lathe and very clean. The steel is untreated 1020 tube. The CHB is a slug that I machined to a precise fit inside the 1020 DOM tube. If CHB is a weldable material, that can be welded with regular filler rods then i'll look elsewhere for the prob...however it only occurred to me on the weekend that I wasnt even sure if CHB can be welded, which is my question.

I hope you didn't use any cutting fluid when you machined it...

No I didnt. But what difference would that make anyway?

The cutting oil can get impregnated in the material causing impurities.
Do you know the Grade of steel.

Would be partly absorbed into that cast steel. You should soak it in metho or acetone anyway, unlikely that it won't have picked up some impurities and probably where your bubbling is coming from.

Similar stuff that he is selling these days is 1045...I couldnt say for certain but I think this is what it is as it rings a bell.

Cheers for the tips re impurities. I didnt know steel could do that. I'll give it a soak and see what happens.

In non-cast metals any oil etc. remains on the surface and are easy to remove.

HI,
Do You mean Carbon Hollow Bar (CHB) ?, if so it is supposed to be able to be Welded quite readily with all the Standard Welding Processes. I know George does Sell a bit of Carbon Hollow Bar on OZTION (Quicksales). Here is a couple of Weblinks 750 CHB 50 x 25 x 183 mm-Steam-Lathe-Model-Weld-Drill-OG for sale | quicksales.com.au item 11739878 and http://buau.com.au/english/files/CHB.pdf . The last link is a PDF and I found it a bit slow to download.

Yeah thats the stuff...my mistake. I always thought the C stood for cast.

I ended up getting it to weld OK after a very thorough clean. Im not sure why but it was much more fussy than welding mild steel.

Gday
Carbon content in steel affects the weldability ,high carbon steels are harder to weld whereas low carbon steels like mild steel are easier to weld.
thanks caveman

Just a little point that many are unaware of.
Many steels that machine well, (free machining steels) do not weld well. This is due to either Sulphur or Phosphorous in the metal.
Sulphur causes HOT SHORTNESS, (weakness when hot).
Phosphorous causes COLD SHORTNESS, (weakness when cold).
As a further point, many machining steels are not adequately deoxidised as they are not intended to be welded, this becomes most apparent when trying to TIG weld them.
If you look at any welding consumables chart, you will note that TIG welding requires a higher grade of filler, at least ES2 from memory, while gas fusion welding can use mild steel filler wire.
I would nearly stake my life on the fact that what you are trying to weld is a free machining grade, (I hope it is not a critical part!).