Entry door repair question?

[Charger Fan]

I have a couple of cracks starting on the aluminum above and below the lock bolt area and I am wanting to find out the best way to repair or replace the problem area?

I had a friend suggest welding the cracks, but I don't know if I care for the the idea or not. My thinking is that it will crack again. It appears that everything is riveted together and that there is what looks to be some sort of "Z" type channel around the door connecting everything together and that appears to be the cracked area.

If I replace the framing, my question is where to buy the material. Is it available or something that needs to be made?

Any help would be grateful.