显微组织对CADI磨球冲击磨损性能的影响

采用油淬+空气等温热处理工艺制备CADI磨球,利用不同的油淬时间获得组织不同的CADI磨球。使用OM、SEM、XRD和冲击磨料磨损试验机研究了显微组织对CADI冲击磨损性能的影响。结果表明:采用短时油淬时,CADI磨球的基体组织主要为下贝氏体;而长时间油淬时,CADI磨球基体形成了马氏体。在冲击功为1.2 J的冲击磨料磨损试验中,马氏体CADI试样在初始阶段耐磨性较好;随着时间的延长,磨损失重越来越大,超过贝氏体为主的CADI试样。冲击磨损过程中,试样会产生形变层,形变层内石墨球和基体的界面处会产生较大应力集中;当组织韧性不足时,裂纹极易从石墨球和基体的界面处萌生和扩展,导致耐磨性下降。

Effect of Microstructure on Impact Wear Resistance of CADI Grinding Balls

CADI grinding balls were prepared by oil quenching and isothermal treatment in air. The grinding balls with different microstructures were obtained due to the different quenching times in oil medium. The effect of microstructure on impact wear resistance of CADI was investigated using OM, SEM, XRD and impact wear tester. The results showed that the microstructure of CADI grinding balls with a short quenching time mainly consisted of lower bainite, while the matrices of CADI with a long quenching time were mainly composed of martensite. In the impact wear test with the impact energy of 1.2 J, the martensite CADI samples showed the better wear resistance in the early stage of the wear test. As time went on, the wear loss was more and more severe, exceeding CADI samples without martensite. In addition, the samples may form the deformation layers, and the stress concentrators appear at the matrix–graphite nodule interfaces. When the toughness of the materials is insufficient, the cracks easily generate from the matrix–graphite nodule interfaces, resulting in wear performance to be diminished.