My fork stem is rusted - should I replace the forks? This is my first post on here. I will try to be as specific as possible, but I'm also new to bike maintenance, so apologies for any wrong terminology.

I have a Giant ATX 2 from 2017, bought second-hand quite recently:



I'm in the process of servicing the headset, but it turned out the stem was pretty well rusted on. It took quite a lot of whacking (with a rubber mallet) and twisting the lock nut etc. to get it free. I'm now looking at the stem on the forks and wondering whether it's worth trying to sand it down and regrease it etc. or if I'm just better off getting new forks. I know they're not great forks (SR Suntour XTC that come with the bike), but I'm trying not to shell out too much if possible (hence getting the bike second-hand).

This is the state of the stem/forks:





Any advice would be greatly appreciated! 

Thanks in advance, 
Jamie
The corrosion can be removed from the steerer with no problems.

If the corrosion was bad and extended into where the top headset bearing sits, there might be a problem as the steerer would not fit into the inner bearing race properly. I can see that is not the case here. (Interestingly you can see where the stem and spacers are positioned on the steerer from the corrosion patterns.)

Clean the corrosion of with a coarse steel wool or high grit emery cloth. Get some decent assembly grease and put a light coat on the steerer, and the stem bolts, interface between stem and handlebar etc.