球化退火对冷精锻齿轮钢20Cr渗碳晶粒度的影响

Effect of spheroidizing annealing on the carburizing grain size of 20Cr cold precision forged gear steel

通过不同球化退火工艺试验,研究退火温度和时间对球化组织和第二相粒子AlN析出物大小、数量的影响,采用伪渗碳法研究试验所得材料耐晶粒粗化的能力。结果表明,冷精锻齿轮钢20Cr在均热温度780℃保温6h球化退火条件下,获得均匀球化组织且第二相粒子AlN析出数量多、尺寸小,在930℃条件下保温时间10h晶粒开始粗化,有很好的耐晶粒粗化的能力。不添加铌、钒、钛等微合金元素,不正火处理,仅通过球化退火提高材料耐晶粒粗化的能力是行之有效的,为实际生产提供新的方法。

The effects of annealing temperature and time on the size and quantity of the second phase particle AlN and spheroidized structure were studied by different spheroidizing annealing process experiments. The resistance to grain coarsening was studied by pseudo carburizing method. The results show that the uniform spheroidized structure of 20Cr gear steel is obtained under the condition of spheroidizing annealing at 780℃ for 6h,and the amount of the second phase AlN is large and the size is small. The grain begins to coarsen at 930℃ after holding for 10 h, and has good resistance to grain coarsening. It is effective to improve the resistance to grain coarsening by spheroidizing annealing without adding niobium, vanadium and other microalloys and normalizing treatment, and a new method for practical production is provided.