I recently came across an issue new to me- wood dust impregnation in joints, and primarily lap joints. It wreaks havoc on my welds. Obviously, cleaning it out would solve the problem, but that is easier said than done. Example- repairing cracks in the liner of a loader bucket, I gouge the crack and grind it all clean but there is wood dust in between the liner and bucket bottom (below the crack in the liner). It doesn't take much, but if your puddle touches any of it the whole thing boils and usually cracks right away- im talking amounts that are barely visible. Even worse, in this case the wood is confined and even debris outside the weld zone gets heated and vents smoke out of the joint to be welded greatly increasing chances of hydrogen cracking.
I do not believe my rods/wire were introducing significant hydrogen. I did use new consumables designed specifically for welding buckets and being crack resistant. It has 90KSI tensile but I think it is supposed to have pretty high elongation. After this weld cracked I used 7018 along with more heat to (hopefully) fix it.
Other than usual joint cleaning/prep, I tried using extra preheat to burn out the wood or off-gas it, with limited success. Maybe I need to just hit it longer and hotter?
Preheat/postheat is not the primary issue but maybe extra precautions needed in this case? I could have done a more thorough preheat/postheat/slow cool and that might help but this has never been an issue before on buckets used in dirtwork, so I went with what worked before. Basically just heat up around 250/300F and weld it. I use a temp gun and/or the acetylene soot "trick" for preheat temp. After re-welding one of my cracked "repairs" I did apply postheat same as preheat for about 15 mins. Not sure yet of the results.
How have others dealt with this issue? Thoughts?
I can think of little else that is more fun than welding heavy equipment. All the variables of debris, contamination, grime, oil, grease, wood and every other element on planet earth that stymies welding it up. What fun... 
Grind it, burn it out, whatever it takes. Just don't keep throwing weld at it when you encounter it, that's my advice.
Grind it, burn it out, whatever it takes. Just don't keep throwing weld at it when you encounter it, that's my advice.
I'd hit it with a rosebud for as long as you can. Get it as close as possible to straight carbon. Still not ideal at all, but better than all the organic muck in there otherwise.
I've had success doing that on large mower deck repairs that had muck on the underside in areas that were inaccessible to cleaning. Gives you a fighting chance.
I've had success doing that on large mower deck repairs that had muck on the underside in areas that were inaccessible to cleaning. Gives you a fighting chance.
Thanks for the input, guys.
CJ737- Seems like all I do is weld on dirty metal
I can usually work around it pretty good but this one was humbling. Your advice is a good reminder though, especially when I get frustrated and just try to push through.
Spartan- my hunch was just burn it out even more, good to have a second opinion. Not really much else that can be done. I have considered drilling a vent hole (outside the joint) near the finish end of the weld in case any pressure does build up.
CJ737- Seems like all I do is weld on dirty metal
I can usually work around it pretty good but this one was humbling. Your advice is a good reminder though, especially when I get frustrated and just try to push through.Spartan- my hunch was just burn it out even more, good to have a second opinion. Not really much else that can be done. I have considered drilling a vent hole (outside the joint) near the finish end of the weld in case any pressure does build up.