The effect of polymeric quenching media on mechanical properties of medium carbon steel

Water and oil are the most commonly used as quenching media in heat treatment processes to harden steel alloy. However, because of the water quenched steel requires to extra treatment (tempering) to yield the preferred properties, and with arising the environmental, disposal, safety and toxicological concerns, there are increased interests in the potential use of alternative quenching technologies. One of the most commonly considered alternatives to quench water or oils are polymer solutions. In this work, a polymer solution of Polyvinyl pyrrolidone (PVP) with different concentrations (15, 20 and 25%) in water was used to quenching samples of medium carbon steel alloy. Also, three bath temperatures (40, 50 and 60°C) were utilized for this investigation. The mechanical properties (tensile, hardness and toughness) in addition to microstructure examination were evaluated for quenched samples and compered to those of water quenched samples. The results show that the best combination of properties can be achieve with 20% PVP quenched samples at 40^oC. This treatment (20% PVP at 40°C) can be used instead of water quenching and tempering treatment for medium carbon steel samples and consequently reduce the overall cost of heat treatment process.