铸铁激光表面改性的组织与性能特征的研究

A Study of the Microstructure and Property Characteristics on the Laser Lurface Madification of Cast Iron

论述了激光表面熔融处理后硬化层的显微组织与性能特征，讨论了组织对硬度分布的影响试验结果表明：经激光表面熔融处理后，球墨铸铁熔化层组织为先共晶奥氏体（快冷后转变为Ｍ＋ＡＲ）＋莱氏体，相变层组织为马氏体＋残余奥氏体＋球状石墨；灰口铸铁的熔化层组织为细小树枝（Ｍ＋ＡＲ）＋弥散分布的树枝间层片状变态莱氏体（Ｍ＋ＡＲ＋Ｆｅ３Ｃ）的变态亚共晶白口组织，相变层组织为马氏体＋残余奥氏体＋片状石墨在相变区，球状石墨周围的组织较复杂，靠近熔化层处的石墨球周围出现双壳层组织，由一层马氏体＋残余奥氏体包围。

This paper deals with the microstructure and property characteristics of hardened layers of cast iron by the laser surface melting process The influence of microstructure on the hardness distribution of hardened layer is discussed The experimental results show that:After lasex surface being melted, microstrcture of melting zone of ductife iron is first eutectic austenite (it turns into martensite and retained austenite after being rapidity cooled ) and ledeburite, microstructure of phase transformation hardened layer of ductile iron is martensite, retained austeite and nodular graphite; In gray cast,microstructure of melting zone is a dendritic structure (M+Ar)and interdendritcly lamina transformed ledeburite (M+Ar+Fe 3C),microstructure of phase transformation hardened layer is martensite,retained austenite and Flaka graphite In phase transformation hardened layer,microstructure around nodular graphite is complex A double-layer structure is composed of martensite and retained austenite together with ledeburite or first eutectic austenite and ledeburite in phase transformation hardened layer dasing to melting aone