En esta investigación se evalúo el cambio microestructural que presenta el acero AISI –SAE 4140 al ser sometido a condiciones de enfriamiento continuo con el fin de analizar la transformación bainítica. Se determinó que la microestructura a distancias de 0.2 a 2mm es martensítico y a distancias mayores de 30mm se observó un comportamiento bainítico. El tipo de bainita encontrada fue del tipo nodular o globular.In this research were evaluates the change microestructural that presents the steel AISI - SAE 4140 to the subjected being to conditions of
continuous cooling with the purpose of analyzing the transformation bainítica. It was determined that the microestructura at distances of 0.2
at 2mm is martensítico and at distances bigger than 30mm a behavior bainítico was observed. The type of opposing bainita was of the nodular
or globular type
