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本文用光学金相显微镜在三点弯曲载荷作用下,观察了不同热处理状态的WC-钢复合材料GJW50断裂全过程;用扫描电镜进行了断口分析。结果表明,随着外加载荷增大,试样下表面张应变量ε_θ增大,当达到最大张应力时便产生显微裂纹。其显微裂纹总是在粗大的WC粒子和硬质相WC聚集区的WC粒子间界面以及孔隙处优先萌生。随着应变量增大,已开裂WC粒子中的微裂纹张开粗化,与此同时,尺寸较小的WC粒子开始产生微裂纹;应变量进一步增加,已开裂WC粒子的裂纹进一步张开,向前发生扩展。并对其扩展的可能途径进行了研讨。
In this paper, the whole process of the GJW50 fracture of WC-steel composites under different heat treatment conditions was observed under the three-point bending load with an optical microscope. The fracture analysis was carried out with a scanning electron microscope. The results show that as the applied load increases, the strain ε_θ on the lower surface of the specimen increases, and when the maximum tensile stress is reached, a microcrack is generated. The microcrack always preferentially sprouted at the interface between the WC particles and the pores in the coarse WC particles and the hard-phase WC aggregates. With the increase of strain, the micro-cracks in the cracked WC particles coarsen. At the same time, the smaller size WC particles begin to produce microcracks; the amount of strain increases further and the cracked cracked WC particles further open, Expanding forward. And discussed the possible ways to expand it.