Is it possible to weld powdered (sintered) metal? The other day at work I was trying to weld onto some powedered metal valve seats in order to remove them and they didn't really like the mig. Does anybody have any suggestions on how to weld them?
Im not quite sure as I have never encoutered something like that.
were the metals (base metal, filler metal and object being welded on) all the same or was one even dissimilar? I have seen a coworker try to use a piece of aluminium tie a ground from one pipe section to a section running paralell and the AL did not take kindly to it. There were scorch marks from the current arcing from one piece to the other along with some pitting that was far in excess of what steel would do.
EDIT: brazing would be the method of choice to bond dissimilar metals and is actually quite strong
I was trying to use a mig welder to add a bead of weld to the inside radius of the powdered seat so that a smaller valve could be used as a punch to remove the seat. it works great on steel and cast iron seats. The PM would just pop and burn off before I could get a bead down. The few parts of weld that stayed looked like I had forgoten to turn the gas on. Could it be that because there are still air pockets in the metal they expand rapidly causing the metal to pop and blow chunks off?
The brazing should work, but I was looking for a quick way to get the job done next time. I was wondering if there was a speical rod/wire or technique to use.
did you try to clean the metal with a grinder first, i know with any kind of paint or rust, including powdercoat, that you first need to clead the spot to be welded or you will get too much "trash" in the weld...
did you try to clean the metal with a grinder first, i know with any kind of paint or rust, including powdercoat, that you first need to clead the spot to be welded or you will get too much "trash" in the weld...
The old seats were cleaned up the best that I could get them. I asked the boss about this and he said that the PM seats just plain suck to try to weld to. The only real hope is that you can get enough of the seat to pop away and it will loose its press fit and fall out.
PM is nearly impossible to weld. You might be able to low amp tig it, but even then I see you having problems. The problem is that PM doesn't have the solid and consistant structure that normal steel has. As soon as you arc too it the material is so inconsistant there's no way for the arc to become stable, thus blowing up in your face.
