2-362-334 - Worldwide Photography/Heritage-Images

Heat treating hacksaw blades, Slack Sellers & Co Ltd, Sheffield, South Yorkshire, 1963. The process of heat-treating metal involves the heating up and rapid cooling of the metal, which changes the properties of the metal but not the shape. Heat-treating is used to harden, soften or increase the ductility of the metal, depending on its intended use. In the photograph, Hacksaw blades hang ready to be immersed in water as part of the heat treatment process. A transparent screen protects the operator.