Just to echo the others saying to reject the beam..
Those cracks have been open for an unknown (to us on the forum) amount of time- but in any case, there is almost certainly the start of crevice corrosion in those cracks (due to exposure to moisture in the air) and in order to truly, properly repair this beam you would need to grind back all possibly corroded material, in every crack, all the way to the crack root, over the full length.
You're talking about a significant time investment with an uncertain end result; it only takes a tiny area to be missed during grinding to result in an internal inclusion which could cause problems in service.
A real repair to this beam would require a great deal of grinding, a great deal of welding, and then a great deal of x-ray/NDT.
Unless this beam has already been shipped to a jobsite in outer Mongolia where it's hard to get a replacement in time, the easier solution for everyone is to replace the beam and it is not close.
The other benefit of rejecting this beam is that if this is a mill or supplier with whom you expect any future business, it is a good precedent for you to set; accept this reject, and they'll 1) be more comfortable shipping you rejects in the future and 2) will try to use this acceptance as justification to strong arm you into accepting substandard material in the future. I.E. 'why can't you accept this beam, you accepted one like this last year and everything was fine'.
Stand your ground- do your present self/project and your future self/projects a favor and send it to the heap.
