Have not done any hardfacing, but looks like I'll be doing some soon. Any advice on how to run it? Hot? Cold? I've seen some very convex beads indicating running it slow and cold. Is there a similar rod you could compare it to as to how it burns? Slow movement? Short arc? Whipping?
I also hear these are quite expensive. How much more are they than common rods? I want wear resistance. Which number should I get?
This is too big a subject to cover in a short post but here is some KISS thoughts. I am assuming we are talking about stick rod application, (MIG is similar).
IMHO, hard material should not be used for build-up of worn material, (too costly and lacks strength and ductility) use 7018 for build-up. If you have some surplus (low$$) 80,90,100 or11018 it is harder than 7018 and is good for the last pass of build-up.
IMHO the most important thing to consider in application is to prevent dilution of the hard material with base material. Your first pass will always be diluted somewhat, you should run hardsurfacing rod on the cold side but consistent with good fusion and without cold-lapping. Use a short arc, no weaving or whipping, similar to xx18. If you have some surplus
80,90,100 or11018 you can use it for the first pass of hardsurfacing and save some $. The second pass of hardsurface weld will be a lot harder than the first.
If you are trying to limit wear from ground engaging surfaces then let the dirt do the work for you. Apply the hardsurfacing in a pattern that will trap dirt and limit contact and abrasion of the base metal. To do this try to make your hard beads stand as tall as possible. The hard wearing beads can be reapplied as needed before they wear down to the first diluted and softer under bead. Even plain 7018 will help reduce wear if applied in a good pattern that traps dirt, but it will need to be reapplied more often.
The numbers vary by supplier but in general higher numbers are harder and more expensive. Some hard rods are designed for impact and others for abrasive wear. Use what you get the best deal on, there is a lot of surplus hard rods of questionable specification that have also had questionable storage for a long time. Dry it and use it, provided that usually there is a very low consequence of failure.
Hardface is run a bit colder than welding rod. The purpose to to add a layer of hard material, not to melt it into the base metal. Preheating is recommended for most applications. The final surface will often have a hazing of fine cracks, but it doesn't mean anything.
Hardface comes in many different flavors. Some are meant for high wear and some for high impact. High wear alloys will have a high percentage of carbides. Either iron or tungsten carbides.
High impact alloys have hard particles in a softer matrix.
For wear resistance look for something in the mid 50's to lower 60's on the Rockwell C scale.
The high impact alloys run in the 40's to mid 50's.
When I was building anvils I used the softer alloys for the under layers, and the harder alloys for the top surface.
I like Rankin and Stoody products, but McKay is also good. UTP and Bohler also have good hardface alloys.
The specifics on the vibrator I am starting with is 2200 impacts per minute, and 960# striking force. There may be variations in models, 2", 3", 4" pipe, etc. Vibrators for the larger diameters would go up into the 2100 impacts per minute, and 2192# striking force. The largest model I would consider using has 1725 impacts per minute, and striking force of 9085#. Hope that tells you something.
I am considering using 2" pipe, or hitch stock, as the potential for getting this thing stuck in the ground underwater is there, and until tested, I won't know. I could go up to 4" diameter at tops, but that would thoroughly depend on bottom, getting stuck, and what type of support vessel this will be operated from, and what sort of davit/crane/backhoe, whatever, is used to pull it out. As an alternative to pipe, and where I want the extra heavy weight for penetration, I may weld four pieces of 1/2", 5/8", or even 3/4" FB together to make a square tube, but leaving suction openings along the seams by using smaller thicknesses of FB as spacers. Probably use a 6010++ to do the root, then, as suggested by private, 11018, as doing a pipeline weld, only using 11018 instead of 7018, then hardfacing over the welds there.
Anyway, I have one vibrator ordered, and will build a prototype, and do some testing here, and in the local ponds, lakes, and streams, if I don't get into too much trouble. It's going to be loud, and a gas air compressor to boot.