加热温度及保温时间对55CrMo钢相变的影响

Effects of heating temperature and holding time on phase transformation of 55CrMo steel

为了改善精密滚珠丝杠感应淬火后的表层硬度及硬度均匀性,提高耐磨性及寿命,利用Gleeble-1500D热模拟试验机,以50℃/s的加热速度,将55CrMo钢试样分别加热到800、850、900、950、1000、1100和1200℃,并在相应温度分别保温8、16和32 s,然后以50℃/s的冷却速度进行冷却,研究加热温度及保温时间对55CrMo钢相变温度、微观组织、显微硬度的影响。结果表明:在快速加热条件下,55CrMo钢奥氏体化温度升高;升高加热温度和延长保温时间均有利于促进奥氏体化均匀,抑制贝氏体转变,有利于增加均匀细小的马氏体组织,改善丝杠表面淬硬层硬度值的均匀性;55CrMo钢感应淬火时,应将感应加热的温度控制在900~1000℃范围内。

In order to improve the surface hardness and hardness uniformity of the precision ball screw after induction hardening, to increase wear-resistance and prolong work life, 55CrMo steel samples were heated to 800,850,900,950, 1000, 1100 and 1200 ℃ respectively with a heating rate of 50 ℃/s, and holding for 8 s, 16 s and 32 s, respectively, then cooled with the rate of 50 ℃/s by a Gleeble-1500D thermal- mechanical simulator. The effects of heating temperature and holding time on the phase transformation temperature, microstructure, microhardness were researched. The results show that the austenitization temperature of the 55CrMo steel increases during rapid heating. The increase of heating temperature and holding time are both helpful to promote austenitizing uniformity, to restrain bainitic transformation. And it is beneficial to obtain uniform and fine martensite microstructure, and improve the hardness uniformity of the hardening layer in the ball screw. The induction heating temperature of the 55CrMo steel should be controlled in the range of 900-1000 ℃.