CrWMn钢切纸刀网状碳化物的分析

Analysis of Network Carbides in CrWMn Steel as Paper Cutting Knife

CrWMn钢切纸刀的显微组织容易出现网状碳化物,网状碳化物所引发切纸刀的刃口微观变化会降低刃口锋利度和耐磨性。根据试验和相平衡热力学计算分析了产生网状碳化物的原因,提出了解决的工艺方法。结果表明,在热轧镶钢后的空冷过程中,容易从过饱和的奥氏体中沿晶界析出颗粒状碳化物,继续堆放冷却会形成网状碳化物;在奥氏体加碳化物的相区长时间恒温也会因晶界上扩散速度快,使碳化物聚集长大而形成网状碳化物,形成网状碳化物的温度区在880～800℃。为了防止网状碳化物形成,热轧镶钢后应风冷或喷水冷却躲过这一温度区,在此温度区进行退火处理的加热恒温时间也不应过长。

The network carbides easily appears in the microstructure of CrWMn steel as paper cutting knife,and the cutting edge sharpness and wear resistance of the paper cutting knife will be lowered by network carbides.In this study,theinfluence of network carbides was analysed and the solution of technical method was put forward.The results show that in the air cold process after hot roll-jointing,the carbide particles precipitated easily along crystal boundary from over saturated austenite,and later piled up in cold process,subsequently the network carbides came into being.During long-time holding in phase field of austenite plus carbide,network carbides formed because of the congregation and growth along crystal boundary because of quick diffusion.The temperature region of forming carbide network of CrWMn steel is 880-800 ℃.Therefore rapid cooling by wind colling or water spraying is obligatory in order to avoid this temperature region,and the holding time of annealingin this temperature range cannot be too long.