【摘要】 研究了不同Nb含量的20CrMnTiH齿轮钢的奥氏体晶粒长大行为。采用光学显微镜和透射电镜分析了试验钢分别加热到950~1200℃奥氏体化保温1 h后的奥氏体晶粒变化和析出相情况。结果表明,随着Nb含量的增加,晶粒粗化温度不断提高。保温时间为1 h的情况下,每增加0.03%Nb,晶粒粗化温度提高50℃;超过晶粒粗化温度后,含Nb析出相的数量因溶解而大大降低,对晶界的钉扎作用消失,奥氏体晶粒长大。更多还原

【Abstract】 The growth behavior of austenite grain of 20 CrMnTiH gear steels with different Nb content was investigated. The variation of austenite grain and precipitated phase of the tested steels austenitized at 950-1200 ℃ for 1 h were analyzed by means of OM and TEM. The results indicate that the more the Nb content is,the higher the austenite grain coarsening temperature is. When holding for 1 hour,the grain coarsening temperature of the tested steel increases 50 ℃ for each additional of 0. 03% Nb. Exceeding the grain coarsening temperature,the amount of niobian particles are greatly decreased because of dissolution,and the pinning effect of niobian particles on austenite grain disappears,which causes a rapid growth of austenite grains.更多还原