变质处理对高强度灰铸铁钻削加工性能的影响

Effect of Modification on Drilling Performance of High Strength Gray Cast Iron

目前,通常采用加Mo高强度灰铸铁生产本体抗拉强度大于250MPa的大马力发动机缸体,由于Mo-Fe价格一直居高不下,使生产成本提高。因此开发低成本、高强度、易加工的灰铸铁具有重大意义。采用变质处理方法,生产满足大马力发动机缸体性能要求的不含Mo高强度灰铸铁,对比研究了含Mo与变质处理不含Mo高强度灰铸铁在钻削加工过程中的钻削抗力、扭矩、钻头磨损形貌、钻屑特征及两种灰铸铁的石墨形态、尺寸、分布和基体珠光体片间距对钻削加工性能的影响规律。结果表明,变质处理可以获得细小、弯曲、均匀分布的片状石墨,能够改善灰铸铁的钻削加工性能,同时提高抗拉强度。这为灰铸铁大马力发动机缸体毛坯国产化生产奠定了基础。

At present, the big horsepower engine cylinder block casting with more than 250 MPa of the bulk tensile strength is commonly made of the high strength gray cast iron with Mo addition, however, the production costs increase because of the high prices of ferromolybdenum. Then, it is of great significance to develop the low-cost, high strength and easy processing gray cast iron. In the present paper, the high strength gray cast iron without Mo which can meet the performance requirements＇ of the big horsepower engine cylinder is obtained by modification. The drilling resistance, torque, wear morphology of the drill bit and the feature of the drilling chips of the high strength gray cast iron with Mo and the modified high strength gray cast iron without Mo during the drilling process were compared, and the effects of the graphite morphology, size and distribution as well as the pearlite lamellar spacing on the drilling performance were studied. The results indicate that the uniformly distributed fine curved flake graphite can be obtained through the modification, which can improve the drilling performance of the gray cast iron, and moreover, the tensile performance, and it will establish the foundation for the domestic production of the big horsepower engine cylinder.