Heat treating and tempering are manufacturing processes used to alter the physical properties of metal and other materials.
Heat treating involves heating the metal up to a very high temperature and then quenching (rapidly cooling) it. This increases the hardness of the metal, but in doing so will also make it more brittle.
Tempering
Tempering is performed after heat treating, and also involves heating the metal, but to a lower temperature than required in heat treating, then letting it cool slowly. Tempering decreases the hardness and brittleness of the metal whilst increasing its toughness.
By controlling the temperature the metal is heated to during tempering, it’s possible to alter the final balance between the hardness and toughness of the metal.
Why is heat treating and tempering important to engineer’s scrapers?
Engineer’s scraper blades are heat treated to harden them. Hardening is necessary to make the blade harder than the workpiece on which it is being used, enabling the blade to remove the high spots from the workpiece.
Scrapers have a greater depth of hardening than most other tools to help them to maintain a sharp cutting edge for longer.
Scrapers are lightly tempered to remove some of the brittleness imparted during the hardening process in order to prevent them breaking during use.