Tempering is a heat treatment that uses a tempering furnace to increase the toughness of certain metals. The steel is heated to just below a certain temperature and then air cooled.
The temperature at which the item is tempered depends entirely on the application of the metal and the desired result, drill bits need to be tempered at a lower temperature than mattress springs.
Tempering is only one heat treatment option for metals. Some other options are annealing and normalization. However, each process leads to different results.
Tempering works best on products that are under a lot of stress, not just drills and springs, but also knives, bolts, nuts, screws, washers and many more common products.
