Car overheating with occasional pinging - 2006 Hyundai Elantra

I had a slow coolant leak and it ran completely dry while driving, causing the car to overheat to the point of engine rattling. The next morning I replaced the coolant, but the car still overheats. It seems to run at a normal temperature for a while and then suddenly spike up, and there is occasional pinging in the engine.

Thank you in advance for any help you can offer.