Quench hardening and mechanical characterization of AISI 4140 steel

AISI 4140 steel is the medium carbon low chromium steel used for a variety of structural applications. Generally this type of steel is available commercially in hot/cold rolled or as-cast conditions. This grade of steel has moderate strength and suitably responds almost to all type of heat treatments especially, hardening treatments. The present work is the effort in improving the mechanical properties of AISI 4140 steel by hardening treatment using different quenchants such as tap water, salt water (brine solution), ice water, castor oil, and coconut oil. Properties under consideration are wear, hardness and tensile strength. The change in property obtained by quenching is compared with that of as-bought steel. Ice water, coconut oil and castor oil quenched specimens show good wear resistance properties. Specimens quenched in ice water shows high hardness value (Rc 51.25). Castor oil quenched specimens show a highest percentage displacement (27.33%) and ultimate tensile strength of 1600.3N/mm2. Amongst the different quenchants used castor oil shows good result as a whole.