fatigue curves of different parent materials and different BSI weld classifications developed by Caterpillar over the last 60 years that I used over the 8+ years I did fatigue analysis on buckets, motograder frames, and other components for them. Tensile strength, with a single static load, yes, a proper weld is stronger than parent material. A well done, fully ground and polished class A weld, fatigue strength is nearly the same as parent material....lesser classifications (say a class C with a cold stop & start at the end) will be significantly lower in weld life. back side looks decent, front looks like somewhere between a B & C, with a big booger of weld that will create a stress riser. also,if doing something like this, you would not want to weld right where the cross section transitions from fairly large to very small (right where the weld is), as that's a geometric stress concentrator, I'd want to see it maybe an inch or so down the leg in the more constant cross section area....
and yes, for fatigue analysis, welds are most definitely modeled with different properties to estimate life.
