Material is a 10 gauge, A572 GR50 TPPO (tempered pass pickled in oil). Process used is GMAW-S, .035 ER80S-D2 wire and 90/10 gas. Problem is, we have had about 6 cracks now on 6 different hydraulic tanks. Some are brand new, never been in service. Cracks are found at the end of the weld. There is a baffle inside the tank that gets 2 fillet welds. You can see where these two fillet welds are on the outside of the tank from where they dimple the steel. The cracks are found in the HAZ just at the end of the dimple.
The crack is so thin and small, that it can barely be seen with the naked eye when no hydraulic fluid is leaking out. The weld on the inside is smaller then an 1/8" fillet. The crack runs almost perpendicular to the weld, just a few degrees off of perpendicular. The crack is about 3/4" long.
So thoughts and opinions are welcome. I'm wondering if the wire might be causing this, but I still think the steel would be durable enough to take the shrinkage. The welder is supposed to be using an ER70S-3 wire, but has apparently been using the ladder shop wire instead of the right wire. I need to go over how to read the wire classifications with him now. ;-)