一种新型胀断连杆用中碳非调质钢

 采用降低铁素体相韧性、提高铁素体相硬度及适当脆化原奥氏体晶界的方法，开发出一种新型胀断连杆用铁素体-珠光体型中碳非调质钢，从钢种设计、微观组织、力学性能及胀断特征等方面对此钢种进行了介绍。硅和磷元素的铁素体固溶强化作用及钒元素析出强化和组织细化作用，使得开发钢不仅具有较高的强度水平和屈强比，同时具有远高于传统的胀断连杆用高碳钢C70S6的优异高周疲劳性能。此外，模拟胀断试验结果表明，开发钢的断口呈典型脆性解理断裂，胀断前后的变形量很小，具有优于C70S6钢的胀断性能，可采用胀断工艺制造连杆。

Development of New Medium-Carbon Non-Quenched and Tempered Steel for Fracture Splitting Connecting Rod

A new medium-carbon non-quenched and tempered steel for fracture splitting connecting rod was developed through lowering the toughness of soft phase of ferrite,increasing the hardness of ferrite and suitable lowering the grain boundary strength of prior austenite.The alloy designing considerations,microstructure characteristics,mechanical properties and fracture splitting characteristics of the developed steel were introduced.The developed steel not only has considerably higher strength level and yield strength ratio,but also has much higher fatigue strength than that of conventional high carbon pearlite steel C70S6,to which fracture splitting process has been applied,mainly owing to the significant solidification strengthening effect of higher content of Si and P elements and the precipitation strengthening and microstructure refining effects of V element.Moreover,the fracture surface was brittle cleavage fracture of simulated fracture splitting specimen.The distortion is smaller than that of C70S6 steel,which suggests that the developed steel can perform fracture splitting with minimal distortion.