离心铸造高铬合金铸铁气门座圈的组织及耐磨性能研究

Microstructure and Wear Resistance of Centrifugal Casting High Chromium Cast Iron Marine Valve Seat Ring

采用离心铸造制备两种高铬合金铸铁气门座圈。利用X射线衍射仪(XRD)、金相显微镜、洛氏硬度计和扫描电镜(SEM),对气门座圈铸态及热处理态后的试样物相组成、金相组织、力学性能及拉伸断口形貌进行了观察和分析,同时在销盘式摩擦磨损试验机上对高铬合金铸铁气门座圈的耐磨性能进行了磨损试验。结果表明,热处理前高铬合金铸铁主要为由初生奥氏体、共晶奥氏体和碳化物组成的铸态组织,经淬火及回火处理后转变为马氏体和碳化物组成的组织,明显提高了气门座圈的硬度和强度,由于基体组织和碳化物的形貌及分布改善,高铬铸铁的耐磨性能在热处理后明显提升。

Two kinds of high chromium alloy cast iron marine valve seat were fabricated by centrifugal casting.The microstructures,tensile fracture morphology and mechanical properties were examined using X-ray diffractometer(XRD),scanning electron microscope(SEM),optical microscope and rockwell hardness tester,the wear resistance were also characterized by the pin on disc tribological tester.The results show that the as-cast microstructure of high chromium cast iron is primary austenite,eutectic austenite and eutectic carbide,and the microstructure after heat treatment is martensite and carbides,the hardness and strength are increased obviously.The wear resistance of high chromium cast iron after heat treatment is also improved due to the improvement of matrix structure and carbide morphology and distribution.