用常规强度试样与粉末冶金零件测定的力学性能的比较

Comparison of mechanical properties obtained from conventional strength specimens and from as-sintered components

由于零件的强度难以试验测定,因此通常都不使用这些数据。这篇论文介绍了一种可直接测定零件强度的新方法。这种方法是采用水射流切割(Water-jet Cutting),从零件上切割小型矩形试棒(尺寸约为40mm×5mm×5mm),经磨加工制备成试棒,用于测定力学性能。这篇论文将由高合金化Fe(Mo)-Ni-Cu粉末冶金钢制造的同步器齿毂作为典型零件,用由其上切割制成的矩形试棒测定了抗拉强度、冲击强度与三点弯曲的横向断裂强度,并将其和用常规拉伸试样(DIN EN ISO 2740)测定的强度与冲击性能进行了比较。由零件试棒和常规试样测定的性能完全一致,都在试验误差范围之内。为证明比较的有效性,还通过全面的化学与显微组织鉴定,对两种试样的相似性进行了核实。采用新方法评定了生产工艺变量对同步器齿毂的力学性能的影响。建立了小拉伸试棒的横向断裂强度与抗拉强度之间的相互关系。

Experimental access to the in-situ strength properties of components is difficult,which explains why such data are not generally available. The present paper introduces a new methodology which permits direct access to the strength properties of components. Such information is retrieved from small rectangular （40mm×5mm×5mm） which are prepared directly from a component by water-jet cutting and subsequent grinding. Using a synchronizer-hub as a typical P/M component, the tensile strength, the impact resistance and the transverse rupture strength in 3-point bending were evaluated from these bars for a high-alloyed Fe （Mo） -Ni-Cu P/M steel, and compared to the strength and impact properties of conventional tensile specimens （ DIN EN ISO 2740）. Within the limits of experimental error,the data sets obtained from components and specimens are fully consistent. To confirm the validity of the comparison,the similarity of both specimen types is verified by a comprehensive chemical and microstructural characterization. The new method is subsequently applied to assess the effects of processing variations on the mechanical properties of synchronizer hubs. Finally, a correlation between the transverse rupture strength and the tehnsile strength of the small tensile specimens is established.