摘要
对DD8合金进行了同位相(IP)与反位相(DP)热机械疲劳(TMF)实验.结果表明:当以机械应变幅作为参量时,在高应变幅下,IP疲劳寿命均低于OP的寿命;随着应变幅的降低,IP疲劳寿命有向OP寿命靠近的趋势.扫描电镜观察表明,IP和OP TMF试样的断口形貌有明显的不同.在IP实验中,裂纹萌生于试样内的铸造孔洞,垂直于加载轴方向扩展;而OP裂纹则是萌生于试样的自由表面,沿着{111}晶面扩展.不同的裂纹萌生和扩展机制是导致IP和OP TMF寿命差异的主要原因.
The experiment of thermo-mechanical fatigue (TMF) behavior of superalloy DD8 shows that when the mechanical strain range is taken as the basis, the life of in phase (IP) TMF is less than that of out of phase (OP) TMF at higher strain ranges. However, with decreasing the strain range, the life of IP TMF is approaching to that of the OP TMF. SEM reveals that there is an obvious difference in the crack morphology of IP and OP TMF samples. In IP TMF, cracks initiated at internal pores and propagated vertically to the loading axis. In OP TMF, the crack initiated at the free surface of samples and propagated alone {111} plane. Different behaviors of crack initiated and propagated are main reason causing the different lifes of IP and OP TMF.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2003年第9期903-907,共5页
Acta Metallurgica Sinica
基金
国家重点基础研究发展规划资助项目 G19990650
关键词
单晶镍基高温合金
同位相
反位相
热机械疲劳
single crystal nickel base superalloy
in phase
out of phase
thermo-mechanical fatigue (TMF)
