The fork looks ok from the pics. I'm not seeing a lot of "corrosion". I'm seeing a weld (maybe a little rough) that was turned on a lathe to provide a proper spot for mounting your bearing race.
How was your fork "refusing to tighten"? If you had all the parts and spacers and bearings installed and the steerer tube was pulling away from the fork crown due to corrosion, and when you tighten the locknut as far as it will go, and still not getting the bearings loaded,, the the fork is toast. If you are missing a part, or if the threads need to be chased (or alternately, have the rust brushed out with a stiff steel brush), then you need to make sure you get the right parts and clean up the threads.
Could it be that you cross threaded the locknut (that is, screwed it on at an angle and not straight)? If not too bad, this can be fixed by chasing the threads. Your LBS should be able to do this.
Well, 3alarmer beat me to the punch. But I note we are giving almost the same assessment and advice - do with this what you will. Good luck.