粉末高温合金包套挤压过程中材料的流动行为及应力分析

对异种合金包覆热挤压过程中材料的流动行为进行了模拟研究和工艺试验验证。结果表明，根据模拟分析得到的挤压力-行程曲线，并结合芯料和包覆材料流动特点，可将异种合金包覆挤压过程划分若干阶段；其中，芯料稳态挤出阶段得到的芯料直径和长度决定了包覆挤压时芯料棒材挤压比和成材率；对芯料稳态变形阶段内芯料和包覆材料典型部位进行应力分析，绘制了典型部位的应力状态矢量图，并采用罗德系数对变形区内两材料的应变类型和变形的复杂程度进行了定量表征；提出了异种合金包覆挤压棒材挤压比计算方法；进一步分析讨论了材料屈服应力对材料流动及挤压比的影响规律；与工艺试验结果对比发现，模拟得到的挤压棒材包覆层厚度与试验结果吻合良好。

Flow Behaviors and Stress Analysis of Materials during Canned Hot Extrusion Process of PM Superalloy

Flow behaviors of the core and the canning during canned hot extrusion have been investigated using FEM and validated by industrial test. The results show that several stages of the extrude process could be concluded based on both the extrusion force vs. stroke curve and the features of materials flow behaviors, which were simulated by FEM. The stage of the core steady flow is of more importance, in which the length and the radius of the core directly determine the bar yield and extrusion ratio. The stress analyses were made in typical locations in cross section of the billet and thus vector distribution of stress state were pictured and the strain type and complexity were quantitatively characterized using Lode parameters. Furthermore, the method calculating the extrusion ratio was proposed and the effect of yield stress on flow behaviors and extrusion ratio was illuminated. The comparison result shows that the thickness of the canning obtained by FEM is well agreement with that in industrial test.