I know. You've been sitting there wondering all day how to tell the temperature of steel when it's glowing. Well hold on to your hats guys, I'll go ya one better. With this easy, fun filled lesson, you can find the temperatures of all metals over 500 degrees!!!
Here ya go, based on color, steel (and other metals) glow:
just visible, very dull red at 500C (932F)
deep red at 550 to 600C (1022-1112F)/ 660C aluminum melts (depending on metal content)
deep bright red (dark cherry) at 700 to 750C (1292-1382F)
bright red(medium cherry) at 800 to 850C (1472 to 1562F)
light red (light cherry) at 850 to 900C (1562 to 1652F)
orange at 950 to 1000C (1742 to 1832F)/ 960.5 silver melts, some brasses and bronzes melt, depending on content
yellow at 1000 to 1100C (1832 to 2002F)/ 1083 Copper melts
yellow to white at 1300+ (over 2362F)/ melting points for lots of other things you don't need to worry about, including nickel at 1453, the next lowest is palladium at 1555C
1539C (2802F) Iron melts, Steel varies depending on content. Steel and iron also easily burn as they approach melting temperature.
Why does this amazing phenomenon happen you ask? Remember high school physics? Well, electrons have natural valence shells around the atom, which is a fancy way of saying they orbit the nucleus at a certain approximate distance.
When heated, it adds energy to the equation, which allows the electrons to jump valences, or orbit further out. As this is not the normal state for the electron, it eventually loses the energy and moves back inwards. Some of that energy is given off as light, causing the glow. Simplifying somewhat, as more energy is added, the photons (light particles/waves) speed up (yes I know, the speed of light is a constant, they actually change frequencies), and the color changes.
Don't hesitate, if this article changes your life, be sure to let me know. As always safety first, heating metal to this temperature may cause injuries up to and including death, as may hanging around with that gangbanger on the corner. Really you should know better. Didn't your mamma raise you right? Sheesh.