Abstract:The softening behavior of a low carbon and high-Nb x80 pipeline steel with different Cr contents under the same deformation conditions has been studied by using a Gleeble-1500D thermomechanical simulator. The static recrystallized fraction was calculated by the offset method,and the influence of temperature and interval time was analyzed. The results show that when the deformation temperature is between 900℃ and 980℃,and when the content of Cr reaches a certain level, there exists a strong effect to solid solubility of NbC of Cr, which can inhibit the static recrystallization of austenite;Futhermore,The addition of Cr can increase the solubility of NbC、decrease the driving force and therefore delay the time of precipitation.