Introduction: Heat Treating Basics

By Underhill Forge
About: I'm a bladesmith from Lancaster County Pennsylvania. I teach knife making classes, forge custom knives for collectors, build my own machinery and am just a little bit of a science geek.

This is a very basic video on some of the underlying process behind heat treating of carbon steels, including normalizing, hardening and tempering. Keep in mind that this is not a definitive work on the subject, more an explanation of the principles involved and the science behind it. Each alloy and grade of steel has different properties and therefore the procedures, while similar, will be different. Shape, size and mass also need to be calculated into your equations. Be aware that when reading technical specifications for steels online that industry standard typically lists the process assuming a 1" cross section, so while the hardening temperatures are the same, the time for soaking may be just a few minutes vs hours and the tempering times may need to be adjusted or split into multiple cycles for the desired hardness. For more information on heat treating specific carbon steels and alloys I highly recommend the ASM Heat Treaters Guide available on both the Apple App Store and Google Play for free.