What kind of rod is this?

"Andrew H. Wakefield" wrote in news:865e9$42a617cb$3f138bb6 $ snipped-for-privacy@DIALUPUSA.NET:

Okay, that is really interesting -- but now I have even more questions!
1) According to the .pdf, 505-16 is a stainless steel electrode, "suitable for welding to base metals of similar composition." The composition of the rod is basically 9% chromium and 1% molybdenum -- does that equate to some of the SS types such as 308 or so on? Could I use this on most "generic" stainless, or is it only useful for certain kinds of SS?
2) Could this rod be used to weld mild steel together, or perhaps tool steel? What would the advantages and disadvantages be, if any?
3) The data sheet says that this is an "air hardening steel electrode" -- I think I know what that means, but any further insight would be much appreciated. I'm assuming this is why the data sheet talks about using pre- and post-heat to gain full ductility. Anybody got any guesses about how brittle it might be if one doesn't pre- and post-heat?
4) Anybody know if this rod needs to be kept dry, like 7018 et al.?
Before I saw Ken's answer, I went ahead (of course!) and tried it out -- it ran very nicely indeed at 75 amps on my ancient AC welder. (I was interested to see in the .pdf data sheet that 505-16 uses a flux that allows running with AC, while another variety, 505-15, was DC only). I was welding onto some scrap mild steel, and it laid down what looked like a nice bead. In fact, the rod acted pretty much exactly like 7018 -- same smooth arc; looked like the same kind of slag that chipped pretty easily; nice even bead. I was getting all set to treat it as 7018, but now I don't know quite what to do with it!
I also ran sample beads with the 5/32" 7018 that I picked up in the same lot at the auction. First time I've ever run a rod larger than 1/8" -- I wasn't quite sure what amperage to run it at, but tried 150. It ran pretty well ... left a BIG bead! I still don't know what I would ever do with something this big, since I mostly work with material 1/4" and less. But it was fun to experiment with it. I seemed to have to keep the rod back just a bit more than I'm used to, but interestingly the rod didn't really ever stick--the rod kept getting into the puddle, but the puddle stayed molten and I could just pull the rod back easily and the arc restarted without any effort.
Thanks to Ken, and to any others that can shed further light on this 505-16 rod!
Andy

500 series in not really a stainless in a pure sense. As you suspect it is more like a tool steel, air hardening. I would suspect the bead would be rather hard. I am wondering just how hard the deposit would be on mild steel. Take a cold chisel to it and let us know. I suspect that if you put a bead on heavy one inch thich mild steel plate not heated that the quencing action would make a brittle enough weld that itowuld crack off.
The titania and lime coating gives an idea of the nature of the coating. The 16 is titania or rutile much like a 6031 while 15 is lime which falls in the same category as 7018 low hydrogen flux. Because this alloy is so strong and hard keeping hydrogen under control would be critical. Preheat of the base metal allows the hydrogen to escape as it cools.
My guess is that you could even use this stuff for hardfacing or forming a cutting edge on a mild steel piece. Randy

Thanks for the further info, Randy. Hmmm -- "use this stuff for hardfacing or forming a cutting edge" -- now that's an interesting thought, and something I'll definitely need to try.
I put some water on the bead and on the mild steel to see what the relative rates of rusting might be. I was thinking I would try a file on it to see how hard it was; I'll follow your suggestion and try a chisel as well. I was welding onto some 1/4" plate, so don't know how much it may have been quenched. (But: air hardening ... ?) I don't have any 1" thick steel plate, or I'd try it just to see how brittle it would get.
One other question: if a person did use this to join two pieces of SS together, what would happen to the underside? As I understand it from posts on this newsgroup, TIG welding SS together leaves a nasty underside unless it is purged with argon. Would the same sort of thing apply using SMAW?
Always fun to learn something new!
Andy
Randy Zimmerman wrote:

All welding electrodes produce a bad weld at an open root on a butt joint except 6010 and 6011 which uses cellulose flux producing massive amounts of carbon dioxide for shielding. Even the cellulose root bead needs a really hot pass to fuse it properly. As a general rule you will see most weld procedures on butt joints involve turning the joint over and gouging out the back side of the weld.... Unless of course such things as back shielding for TIG or a backing bar are used to keep the oxygen away. I wouldn't bother using it for joining regular 300 series stainless if you need strength. What I have just written is not quite right. The weld might be very strong and at its edge it may not have enough ductility to withstand shrinking stresses and crack before reaching room temp. I would bet that the electrode would make a great surfacing rod for some sort of hammer. By pre and post heat you could dial in hardness yet have a soft supporting structure to the body of the hammer. Randy

No, there are a lot of open butt pipe welds made with 7010 and 8010, and 7018 is used under some circumstances. And, the hot pass is to burn out wagon tracks on the outside of the bead, if the shoulders aren't burnt off on the bead, you won't catch them with a hot pass.
JTMcC.

I was waiting for that John... :')) I have also done roots with 7018 but only on a test. I leave that one for better men than I. Randy

I think it's more common in the Boilermaker world than anywhere else, in this country. I think it's just stupid, but nobody ask me.
JTMcC.

Hey, John, I'm glad to see you chime in on this. One of the specific applications mentioned in the data sheet for the 505-16 was for welding certain kinds of pipe. Have you ever had occasion to use this stuff?
Randy or John, I can understand using 6010 (or 7010 or 8010, which I'm assuming are stronger versions of 6010?) for the open root on regular steel, but the data sheet for 505-16 implies use on stainless steel. My impression from other posts on this newsgroup was that SS posed special problems on the backside unless purged -- but those posts were always in connection with TIG welding. If you were welding stainless pipe with this 505-16 rod, would you have to worry about the backside of the weld? (For that matter, what do you do when you are TIG welding SS pipe and can't get to the backside to purge??)
John, I have to confess my ignorance -- help me to understand what you mean by "wagon tracks"?
Many thanks, all, for continuing my education!
Andy

No i've never used it. All of the ss piping I've ever worked with, or around was welded with tig bead/hot pass. Then either tig or stick fill/cap. Always with a purge, except for structural applications. I've heard guys talk about running beads on pipe with stick, downhill, but not in critical piping. Wagon tracks are the deep, hard to clean grooves down each side of the bead, they contain slag and the hot pass melts the grooves out, and floats the slag to the top.
JTMcC.

When the radiographic image is developed the lack of fusion between the root and hot pass shows up like little intermittent wagontracks. The highly convex and cold root bead needs a really hot pass to ensure that both edges of the root are melted and fused into each side of the joint. When doing multiple passes it is really important to avoid convex welds because the following weld has to melt out the valley at each side of the weld bead. If one has welded a highly convex bead and has to put another pass on top it is prudent to use a grinder to flatten out the area before putting down the next pass. sometimes this corrective action is not allowed by code or test requirements. It is a lot better to correct a situation before it happens rather than cover it up. Randy

I am no expert, but don't think your rod would be good for welding Stainless. As I understand it, you want a rod with a higher chrome content than the material you are welding. I think your rod is more for hard surfacing than for welding stainless.
Dan

Aha -- that makes perfect sense -- one of those things that is so obvious once it is explained that I wonder how I didn't get it right away!
Thanks again!
Andy