硼对60Si2Mn弹簧钢连续冷却相变行为的影响

Effect of Boron on Continuous Cooling Transformation Behavior of 60Si2Mn Spring Steel

以国产的60Si2Mn含硼弹簧钢为研究对象,利用Gleeble 1500热模拟实验机和高温共聚焦显微镜,进行临界相变温度和动态CCT曲线的测试,并进行不同冷却速率下弹簧钢在连续冷却过程中先共析铁素体生长过程的原位观察。结果表明,含硼26 ppm与不含硼弹簧钢发生完全马氏体转变的临界冷却速率分别为10℃/s和13℃/s。硼元素的加入,使临界冷却速率降低,提高了过冷奥氏体的稳定性,抑制了晶界处先共析铁素体的析出,阻碍了奥氏体的共析分解转变。另外,随着冷却速率的增大,晶界处的先共析铁素体明显减少。

Taking the domestic 60Si2Mn spring steel containing boron as the research object,the critical phase transition temperature and dynamic CCT curve were measured by Gleeble 1500 thermal simulator and high temperature confocal microscope,and the growth process of pre-eutectic ferrite during continuous cooling of spring steel under different cooling rates was observed in situ.The results show that,the critical cooling rates of complete martensitic transformation in 26 ppm and non-boron spring steels are 10℃/s and 13℃/s,respectively.The boron element is added so that the critical cooling rate is reduced,the stability of undercooled austenite is improved and the precipitation of pre-eutectic ferrite at grain boundary is inhibited,and the eutectic transformation of austenite is hindered.In addition,with the increase of cooling rate,the pre-eutectic ferrite at the crystal boundary decreases obviously.