Popular Heat Treat Colors for Steel Chart is Back

Heat treat colors for steel by temperature.

My “Temper Colors for Steel Chart” post remains very popular, so I thought I'd repost the chart illustrating the heat treat colors for steel.

These days, pyrometers are affordable. But it is the mark of a craftsman to be able to tell temperature by eye, if only to validate the instrumentation (or suspect it).

These colors were obtained from a 0.40 wt. percent carbon, alloy steel, as seen through a furnace peep hole during average daylight conditions.

Originally posted on PMPAspeakingofprecision.com blog.