Analysis and Description of the Three Stage Heat Treatment Required in the Fabrication of an Adjustable Die (Thread cutting tool) from a High Carbon Spring Steel

Abstract

This work constituted the appropriate heat treatment required in converting high carbon steel (spring steel) to a machine-able sample or tool steel. The study of their mechanical and microstructural properties, to further determine the application of these materials in the manufacturing industry and engineering purposes. The sample for research is a high carbon steel (2.0 percent carbon) cut out of a lorry spring. The sample is hot worked to the required shape and size. It is then annealed from a temperature of about 850°C to room temperature, over a period of six hours in an oven. The mechanical property and microstructural analysis test were carried out after annealing. A hole is drilled at the center of the sample using a 4.5mm drill bit; the hole is threaded using a 0.25mm standard screw tap after which it is cut into two equal halves. The resulting Die (a thread cutting tool) is now heated to a temperature of about 650°C and quenched in red oil austentically to room temperature, to increase its hardness and toughness. Brinnell hardness test was carried out on the resulting tool. The resulting Die (thread cutting tool) was used to thread several samples of steel from low medium carbon steel. The result of our analysis shows that, with proper heat treatment high carbon steel can be converted to sample that is ductile to be machine; also the ductile and machine-able sample can be re-hardened and made rough, thereby acquiring the properties of tool steel.