Just reading the description, the MET Impex looks like a high carbon steel.....very hard, but not very tough. If the bucket is wearing out from abrasion rather than impact it might be a good idea. If the wear out is more bending the other steel could be better choice. Boron tends to add hardness while preserving some toughness.
It is supposed to be a boron steel, which is why I bought it.
Bruxite
When I cut the original PT blade off, I discovered that about two feet of welds were cracked in half, I.e. in the middle of the weld. (Lack of preheat, hydrogen embrittlement, one too many times getting deformed by a rock?)
I finally welded the new blade on last weekend. The specifications for welding Bruxite are to preheat to 50 degrees C, (122F) and do not exceed 225C (437F) 3" from the weld. The other bit of advice I got was that keeping the welds warm (long, slow cooling) and doing repeated passes would help reduce hydrogen embrittlement of the welds. I used a Harbor Freight million BTU propane torch to do the preheat, and I wouldn't advise trying with less than 500,000. I used a silicone rubber treated fiberglass welding blanket from Amazon to keep the blade wrapped and warm wherever I wasn't welding.
Firing up the million BTU torch, we got the blade and bucket up to 70C, which was loud. I used a new can of 1/8" 9018 rods. I stitch welded, with 3" stitches, the back side going the opposite direction to how I was proceeding across the back bucket edge. Using about five or six passes, I laid down enough weld to match the thickness of the new blade to spread the load on the bucket, tying both bucket floor reinforcements into the blade. The top leading edge I stitch welded a continuous seam weld in about five passes of stitches until it was all joined up.
I had two helpers, one grinding the flux off between passes and one keeping a eye on the temperature with a calibrated IR thermometer so I could hop around the blade welding different areas and warming the areas up that were cooling down. We needed about three heat boosts during the welding for edges that cooled off too much (getting close to 50C), but once it was at 70C the blade mostly stayed there. When I was done, I wrapped the blade in the blanket and left it to cool slowing.
It took a bit of adjusting in the beginning to get the current up enough to get a good weld puddle on the new 3/4" thick blade. The other "fiddly" bit was turning the blade over and end for end to enable me to do all of the welding horizontally. It was my first time welding with 9018, I did get get better with time, but learning on a critical job isn't my favorite time to learn. (Not complaining!
@MossRoad has the best learning on the job inches from death story that I know.)
Oh, yeah, and my HF cheapo welding helmet darkened out during the job, which made seeing the welds...challenging. Ordered a new 4C helmet to replace it. No real complaints on the helmet as it has lasted for a decade of hobby use. It just wasn't ideal timing.
Overall: If I were to do it over, I think that I should have gone for the bolt on blade and bought myself an annular cutting magnetic drill to put holes in the blade. It was by far the most complex welding project that I have done because of the once you start, you are committed for the whole job to minimize the chances your welds might crack. Still, I learned lots, and had a chance to practice welding. (Used a Lotos LTPDC2000D welder/plasma cutter)
All the best,
Peter
P.S. four days later, with light use, no cracks on the welds. Yay!
