EFFECT OF QUENCHING MEDIA, SPECIMEN SIZE AND SHAPE ON THE HARDENABILITY OF AISI 4140 STEEL

The purpose of this study is to investigate the influence of different quenching media, size andshape of the specimen on the hardened depth of AISI 4140 steel. The paper demonstrates howthese parameters can affect the hardness from the surface to the core of the samples. This studyrepresents the relationship between hardened depth and geometry. Findings reveal the fact thathigh hardening effect was obtained in water-quenched samples by the virtue of the martensiticstructure and lower hardened depth achieved in the air-quenched samples. Significant improvement achieved by increasing the velocity of air when quenched by compressed air. It was also concluded that the hardness of the quenched samples at certain depths can be estimated on the basis of heat transfer equations.