稀土镁变质对船用气缸套减摩铸铁组织和性能的影响

Effect of RE(Mg) Modification on Microstructure and Properties of Antifriction Cast Iron for Marine Diesel Cylinder Liner

研究了稀土镁变质剂对大型船用低速柴油机气缸套减摩铸铁组织和性能的影响。结果表明,稀土镁变质处理气缸套铸铁的石墨形态为A型石墨+少量团块状和近球形石墨;增加RE用量,石墨更细化,端部钝化明显,短棒状和近球形石墨数量增加。稀土镁变质气缸套铸铁的基体组织为珠光体+断网硬质相,增加稀土则增加组织的硬质相数量。适当增加变质剂中RE含量有利于提高铸铁的强度和硬度,采用0.10%RE2Mg6+0.45%RE10Mg5+0.10%RE24Si Fe处理试块的强度和硬度可达269 MPa和252 HBW,且强度和硬度的均匀性提高。

Effect of REMg modification on microstructure and properties of cylinder liner for heavy marine diesel engine were investigated. The results show that the graphite morphology of cast iron modified by RE（Mg） is composed of A type graphite and a small amount of bulk or near sphere graphite. With the increasing of RE content, the graphite becomes smaller and the tip of graphite becomes obtuse, the amount of rodlike and near spherical graphite increases. The matrix of RE（Mg） modified cast iron is consisted of pearlite and broken network hard phase. The amount of hard phases increases with the content of RE. The tensile strength and Brinell hardness of cast iron are improved by REMg modification. The tensile strength and Brinell hardness of cast iron, modified by0.10% RE2Mg6＋0.45% RE10Mg5＋0.10% RE24 Si Fe, are 269 MPa and 252 HBW, respectively.