If I super heat a metal and it turns visibly red what is happening? Was it already emitting infrared and as it gets hotter the frequency shifts up? Or is it still emitting infrared but has a wider band of frequencies it is emitting as well (i.e. is it emitting frequencies below infrared as well as visible red)?

I watched it all the way through when it came out, haven’t done a complete rewatch but I keep going back and re-watching specific skits many times over.