That doesn't really sound quite right. I've never seen anyone with an i5 6600k overclock it that 4.7GHz without ever touching the vcore. That is quite impressive though, if it is true, so congrats.
But to make sure the overclock is actually stable, I suggest you open BOTH a CPU stress testing program like Aida64 AND also have a GPU stress test program like furmark or something to stress both at the same time, and run it over a couple of hours. If there is no crashing whatsoever, then congrats! The overclock is stable.
If it doesn't, then its obvious that the vcore is too low, and you would need to raise it. As for the temps, it is good (assuming the temps you stated are during gaming). and I don't think you need to worry about it...