Zork,
You need to approach this from a quality control standpoint. Your bucket's weld looks like a cold joint and therefore defective from the original factory fabrication which makes this not a warranty issue but a quality control defect.
I have a 6' box scraper that was manufactured here in California that was over a year out of warranty when one of the ripper tines caught a root and bent/ripped the tine
bracket backward and up. I was of the attitude that I would contact the manufacturer and order a new bracket and weld it up myself so I detached box scraper from the tractor and flipped it over to start the grind-off proceedure and saw that practically every tine bracket severely lacked
any welding whatsoever and where there were welds, most looked cold.

I fired off an email to the manufacturer stating my findings along with what dealer I bought it new from and the issue of it being out of warranty and poor quality control during fabrication. That same day my dealer called me to arrange for
them to drive thirty miles to my home, pick it up, repair and re-weld all of the underside tine brackets. Still on the same day I received a reply from the manufacturer that they will make it good and sorry for the incovienence on their behalf.
Two days later it was re-delivered and the driver, this time by the fellow who did the actual welding repair work. He had it loaded upside down on the bed of a small boom truck so I could inspect and approve the new welds and paint which I did. He also insisted that he assist me in re-attaching it to my tractor to make the process complete. No one has ever helped me attach any of my seven implements but this guy wouldn't take "no" for an answer!

Happy ending and a restoration of the selection I made when I originally bought the product.