【作者】 许辉； 张振军； 崔传勇； 孙晓峰； 金涛； 张哲峰；

【Author】 Xu Hui;Zhang Zhenjun;Cui Chuanyong;Sun Xiaofeng;Jin Tao;Zhang Zhefeng;Shenyang National Laboratory for Materials ScienceInstitute of Metal Research,Chinese Academy of Sciences;Superalloy Division,Institute of Metal Research,Chinese Academy of Sciences;

【机构】 中国科学院金属研究所沈阳材料科学国家(联合)实验室； 中国科学院金属研究所高温合金部；

【摘要】 前期研究表明,在新型涡轮盘用高温合金中增加Co含量能够降低层错能,从而导致合金在650和725℃下的抗拉强度和均匀延伸率同步提高,这是由于降低层错能后变形孪晶密度增加所致。为了更好理解层错能对高温合金变形机制的影响,选取3种不同Co含量的新型涡轮盘用高温合金开展轴向总应变幅控制的650℃低周疲劳实验。应变幅在0.3%-0.8%之间,波形为三角波。利用扫描电镜和透射电镜,系统研究了层错能对疲劳变形机制,微观组织演化,以及变形机制和疲劳性能之间的内在联系。结果表明,3种合金在不同应变幅下均表现出不同程度的循环软化行为。降低层错能后,低周疲劳性能有所提高,与拉伸结果类似,这是由于变形孪晶的强韧化行为所导致。这一结果揭示了变形高温合金可以通过降低层错能来改善其疲劳性能。更多还原

【Abstract】 Our previous studies have showed that the ultimate tensile strength(UTS) and uniform elongation(UE) of new disc superalloys were improved simultaneously when Co content was increased,i.e.decreasing stacking fault energy(SFE) at temperatures of 650 and 725℃,which was attributed to the increase of the density of microtwins introduced by lower SFE of alloys.For the better understanding of SFE on deformation behaviors of superalloys,low cycle fatigue(LCF)tests were performed on three nickel-base disc superalloys with Co content ranging from 5 to 23(wt.%) under a fully reversed axial total strain control mode at 650℃.The strain amplitudes are0.3%to 0.8%,the waveforms are symmetrical triangular wave.The dependence of LCF deformation mechanisms on SFE and the relationship between LCF properties and deformation mechanism were systematically studied using scanning electron microscope and transmission electron microscope respectively.It demonstrated that cyclic softening occurs to varying degrees in all the three alloys under various total strain amplitudes.Deformation microtwins cutting across the γ matrix and γ’ phase is the dominant mechanism for the three alloys.The enhanced LCF properties of the new disc superalloys are attributed to the decease of SFE,which is analogous to the case of tensile tests.This result is a good evidence for the strategy of improving LCF property by decreasing SFE in superalloy.更多还原