无缸套汽油机缸体铜铬锡合金化工艺及基体强化作用的研究

The Cu-Cr-Sn Alloying Process and Its Strengthening Effects on Petrol Engine Cylinder Block Without Cylinder Sleeve

针对提高HFC4GA1无缸套汽油发动机缸体硬度等力学性能指标,借助于光电直读光谱仪炉前在线检测、LeitzMM6金相显微镜观测等测试分析技术,对铜铬锡合金化工艺、高效复合孕育工艺技术以及合金化前后的缸体组织性能开展较系统深入研究。研究结果表明,采用铜铬锡合金化工艺,在出炉铁液中添加并控制铜、铬、锡三种元素含量分别为0.30%～0.50%Cu、0.20%～0.30%Cr、0.04%～0.06%Sn,可在保证抗拉强度等其它性能的同时有效提高缸体硬度;且当Cr约含0.25%、且wCu∶wCr∶wSn约10∶5∶1时,缸体各项力学性能较佳。此外,同时采用高效复合孕育剂(Si75%,Ba2%,稀土元素2%)进行二次孕育,并加强流程控制、加速缸筒冷却,可进一步有效强化基体、达到缸体硬度指标,满足缸体生产各项技术要求。

With the increasing demand of petrol engine, the manufacture of the cylinder block without cylinder sleeve is more urgent at present. Considering the need for raising the matrix hardness of HFC4GA1, Cu-Cr-Sn alloying process, high-efficiency compound inoculation technique, as well as the performance of the alloy before and after alloying were investigated, and some analysis techniques were employed, such as the photoelectric direct-reading spectrometer, on-line monitoring and Leitz MM6 metallographic microscope, etc. Results showed that controlling the Cu, Cr and Sn in the range of 0.30%-0.50%, 0.20%-0.30%, 0.04%-0.06%, respectively, especially when Cr is at about 0.25% and the WCu：WCr：WSn is at about 10：5：1, the HFC4GA1 cylinder block casting with high hardness and high strength can be produced by using high-efficiency fading-resistant inoculant for secondary inoculation treatment, and through taking process control to accelerate the cooling of cylinder block, the hardness of cylinder block can reach more than HB190.