对C70S6非调质钢的过冷奥氏体连续冷却转变曲线进行了合理测定,采用力学性能测试、金相检验、疲劳性能测试等方法对C70S6非调质钢胀断连杆的品质进行了分析。结果表明:轧钢过程中采用高温扩散加热及控轧控冷工艺可得到均匀稳定的轧后组织;控制锻造后冷却速率可使连杆显微组织中的铁素体占比远低于10%,并有效防止出现马氏体等异常组织;最终制作的C70S6非调质钢胀断连杆的各项理化性能指标和疲劳寿命测试结果均能满足使用要求。

The continuous cooling transformation curve of undercooled austenite of C70S6 non-quenched and tempered steel was reasonably measured. The quality of the connecting rod of fracture splitting of C70S6 non-quenched and tempered steel was analyzed by mechanical property test, metallographic examination and fatigue performance test. The results show that uniform and stable microstructure after rolling could be obtained by high-temperature diffusion heating and controlled rolling and controlled cooling in the rolling process. Controlling the cooling rate after forging could make the ferrite proportion in the microstructure of the connecting rod far below 10%, and effectively prevented the occurrence of abnormal microstructure such as martensite. The physical and chemical properties and fatigue life test results of the final C70S6 non-quenched and tempered steel connecting rod of fracture splitting could meet the operation requirement.