Tempering (metallurgy)

Differentially tempered steel. The various colors produced indicate the temperature the steel was heated to. Light straw indicates 204 °C (399 °F) and light blue indicates 337 °C (639 °F).[1][2]

Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys. Tempering is usually performed after hardening, to reduce some of the excess hardness, and is done by heating the metal to some temperature below the critical point for a certain period of time, then allowing it to cool in still air. The exact temperature determines the amount of hardness removed, and depends on both the specific composition of the alloy and on the desired properties in the finished product. For instance, very hard tools are often tempered at low temperatures, while springs are tempered at much higher temperatures.

  1. ^ Light, its interaction with art and antiquities By Thomas B. Brill - Plenum Publishing 1980 Page 55
  2. ^ Andrews, Jack (1994). New Edge of the Anvil: a resource book for the blacksmith. pp. 98–99