I built an excavator bucket this winter. Haven't used it yet but i did notice a crack in a joint.
Here is the deal. There is a round pin, diam. about 3", welded into a hole in 1" mild steel. The pin is 4140 tool steel.
Anyway, the machinist who made the pin for me told me to preheat the pin before welding. He was concerned with cracking.
I used .045 solid migwire, preheated the pin and mild steel. The weld went well.
After i was done, i post-heated the weld area to red hot and let it cool slowly in air.
During paint prep some time later, i noticed a crack in the weld area.
What can i do? How do i prevent it from cracking?