oil "oozing" out of ferrous metal while welding
Posted: Fri Nov 05, 2010 12:56 am
I ran into something I thought really strange playing around in my shop the other day, while trying to kill off an argon bottle that was almost dead.
I had broken a harbor freight tailpipe expander tool, (like the one pictured here:)
The end cone shaped piece that rams the multiple pieces outwards had broke into two pieces, and so I tried to TIG weld it for kicks, just to see how it would weld. It fractured in a kind of brittle like manner, not much ductility. So the broken pieces fit together almost perfectly. I thought at first, maybe it was some kind of hardened, heat treated steel. But it didn't really look like it was machined... it had the appearance more of a "cast" part.
To prep for welding, I didn't vee anything out, I just wiped it with a little brake parts cleaner, scrubbed it by hand with a steel wire brush, and went to town with the TIG. Immediately the arc struck it reacted and seemed dirty and "contaminated", the metal was fizzing and popping sparks and smoking, but after a first "heat cleaning" pass, going over the same spot the puddle actually flowed quietly and welded nicely (and I dabbed in some E70S6 filler.)
What was really weird is that after the part heated up, I found it was sitting in a puddle of oil that had leaked out of the ferrous metal! There was quite a bit of oil that leaked out!
What kind of metal is this, that can have so much oil soaked into it? I've heard of things "migrating around grain boundaries" of certain metals, but I was totally surprised about that oil that came flowing out of the part when I heated it up. Might this piece have been made by sintering together steel powder?
I can add that it wasn't tremendously strong in service. I mean, I was kind of abusing it, but I was surprised when it did fracture. I wasn't even using it that far off from how it was intended to be used.
I should also add that I did get a halfway decent weld on it (I welded the nut together with it for more strength) and after dressing the flats with a flat file, I think its actually going to work as good or better than new! I already got a new replacement so it will be interesting to see if the new one works better than the old "repaired" one.
I had broken a harbor freight tailpipe expander tool, (like the one pictured here:)
The end cone shaped piece that rams the multiple pieces outwards had broke into two pieces, and so I tried to TIG weld it for kicks, just to see how it would weld. It fractured in a kind of brittle like manner, not much ductility. So the broken pieces fit together almost perfectly. I thought at first, maybe it was some kind of hardened, heat treated steel. But it didn't really look like it was machined... it had the appearance more of a "cast" part.
To prep for welding, I didn't vee anything out, I just wiped it with a little brake parts cleaner, scrubbed it by hand with a steel wire brush, and went to town with the TIG. Immediately the arc struck it reacted and seemed dirty and "contaminated", the metal was fizzing and popping sparks and smoking, but after a first "heat cleaning" pass, going over the same spot the puddle actually flowed quietly and welded nicely (and I dabbed in some E70S6 filler.)
What was really weird is that after the part heated up, I found it was sitting in a puddle of oil that had leaked out of the ferrous metal! There was quite a bit of oil that leaked out!
What kind of metal is this, that can have so much oil soaked into it? I've heard of things "migrating around grain boundaries" of certain metals, but I was totally surprised about that oil that came flowing out of the part when I heated it up. Might this piece have been made by sintering together steel powder?
I can add that it wasn't tremendously strong in service. I mean, I was kind of abusing it, but I was surprised when it did fracture. I wasn't even using it that far off from how it was intended to be used.
I should also add that I did get a halfway decent weld on it (I welded the nut together with it for more strength) and after dressing the flats with a flat file, I think its actually going to work as good or better than new! I already got a new replacement so it will be interesting to see if the new one works better than the old "repaired" one.