20Ni3Mo渗碳钢深冷强化研究

Cryogenic treatment of 20Ni3Mo carbonized steel

为提高牙轮钻头的使用寿命,用20Ni3Mo代替20Ni4Mo钢,并采用930±10℃×6h的渗碳淬火工艺预处理后,再用液氮及其蒸发空间温度梯度制冷深冷处理。通过磨损试验和透射电镜观察TEM组织表明,深冷处理后,20Ni3Mo钢硬度提高72HRC,耐磨性提高89%,其组织为均匀马氏体、残余奥氏体和微细碳化物。残余奥氏体转变为马氏体及超微细碳化物的析出是提高20Ni3Mo渗碳钢硬度与耐磨性的重要原因。

To improve the service life of cone bits, 20Ni3Mo steel is used instead of 20Ni4Mo steel, and 930±10℃×6h carburization and hardening technology is adopted and then cryogenic treatment in liquid nitrogen is executed. Wear test and TEM observation of the microstructure show that, after cryogenic treatment, the hardness of 20Ni3Mo steel, with uniform martensite, residual austenite and fine carbide, is improved by 7 2HRC, and its wear resistance is increased by 89%. Precipitation of martensite and ultrafine carbide translated from residual austenite is one of the key reasons of the improvement of hardness and wear resistance of 20Ni3Mo carbonized steel.