Looks like aluminum shaft welded to motor housing. I don’t see a crack. I see rust in two spots. Especially black paint which doesn’t run good, is usually thicker, and hates corners… will have a hard time sticking in those areas as there is likely micro crevices that held moisture and didn’t allow the paint to get into them corners.
I would have zero concerns.
Yes, I work everyday with aluminum and steel welders, painting and chrome processes as well as many other similar technologies in my past. Your good! Cover it with sharpie if you don’t like the orange.