The assessment of the structure and properties of high-carbon steel wires after the process of patenting with induction heating

Abstract

One of the most important types of heat treatment that high-carbon steel wires are subjected to is the patenting treatment. This process is conducted with the aim of obtaining a fine-grained uniform pearlitic structure which will be susceptible to plastic deformation in drawing processes. Patenting involves two-stage heat treatment that includes heating the wire up to the temperature above Ac3 in a continuous heating furnace (in the temperature range of 850/1050°C) followed by a rapid cooling in a tank with a lead bath down to the temperature range of 450/550°C. The patenting process is most significantly influenced by the chemistry of the steel being treated, as well as by the temperature and the rate of heating and cooling of the wire rod or wire being patented. So far, heating up to the austenitizing temperature has been conducted in several-zone continuous gas-fired or electric furnaces. Recently, attempts have been made in a drawing mill to replace this type of furnace with fast induction heating, which should bring about an energy saving, as well as a reduced quantity of scale on the patented wire. This paper presents the analysis of the structure and mechanical properties of wires of high-carbon steel with a carbon content of 0.76%C after the patenting process using induction heating for different levels of the coil induction power.