Indian Journal of Science and Technology

Abstract

Medium carbon steels are high strength steels which include AISI4140 as an important member in low alloy category. These steels show positive response to all variety of heat treatments. The present work aims to experimentally investigate the properties like Tensile, Hardness and Impact Strength on AISI4140 steel. The as-bought properties of AISI4140 steel have good ductility, shock resistance but low wear resistance and shorter service life. However such properties can be further improved through various heat treatment processes. In the present investigation the effect of dual phase heat treatment and mechanical property analysis of AISI 4140 are studied. The effect of normalizing as pretreatments on dual phase structure and property at different inter-ctitical temperatures holding for 2 hours followed by water quenching are investigated in view of improvement in mechanical properties like hardness, impact toughness and tensile. Test specimens are prepared and subjected to preliminary heat treatment. The dual phase structures (Ferrite-Martensite) by heating to three different inter-critical temperatures are obtained by rapid quenching in water medium. The resultant dual phase microstructure is also studied. Then tensile, impact and hardness tests are conducted and compared with asbought condition results. The dual phase steels find applications widely in automobile parts and general constructional applications where wear resistance is of the serious concern.
Keywords: Austempering, Annealing, Dual Phase Ferrite, Martensite, Steels