M.F. Geng(Luoyang Ship Material Research Institute
,
Luoyang 471039
,
China)
金属学报(英文版)
The crack growth behavior and fracture feature of superalloy GH2132 (equivalent to A286) under creep-fatigue conditions have been studied in the present paper. The tests were carried out at 550℃ under various cyclic freqencies (hold time) and load levels,and the fracture surfaces were examined by using a scanning electron microscope. It is shown that the fracture mode of creep-fatigue and the effect of cyclic loading on crack growth change with the growth of crack and the increase of net-section stress,and both are reversed when the net-section stress is up to the yield stress of material.When σn <σ0.2, cracking is predominantly cycle-dependent transgranular and cyclic loading accelerates creep crack growth, whereas when σm>σ0.2, the case is reversed.
关键词:
creep-fatigue
,
null
,
null
,
null
,
null
,
null
N. Tada
,
T. Kitamura
,
R. Ohtani and E. Nakayama (Department of Engineering Physics and Mechanics
,
Graduate School of Engineering
,
Kyoto University
,
Yoshida-hommachi
,
Sakyo-ku
,
Kyoto
,
606-8501
,
Japan)
金属学报(英文版)
Creep-fatigue test was carried out using smooth round bar specimens of Type 304 stainless steel. Cavities and small cracks on the cross-section of the specimen were carefully observed by a scanning laser microscope. Moreover, direct current electrical potential method (DC-EPM) was applied in order to evaluate non-destructively the distribution of internal cracks. The distribution evaluated by DC-EPM agreed well with the actual one.
关键词:
creep-fatigue
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null
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null
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null
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null
田阳
,
赵姿贞
,
陈巍峰
,
陈旭
机械工程材料
doi:10.11973/jxgccl201603001
利用液压疲劳试验机,采用轴向应变控制方法在455℃下对2．25Cr1MoV 钢进行高温低周疲劳试验,通过在峰值应变拉伸时保载0,60,600 s,研究了拉伸保载时间对该钢低周疲劳行为的影响,并用扫描电镜对断口形貌进行了观察.结果表明：2．25Cr1MoV 钢呈明显的循环软化特性,拉伸保载会明显降低循环应力幅,但保载时间对循环应力幅的影响不大；拉伸保载使该钢的疲劳寿命降低,但保载时间超过60 s 后,疲劳寿命基本不受保载时间的影响；拉伸保载没有改变试验钢的疲劳断裂模式.
关键词:
2.25Cr1MoV 钢
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低周疲劳
,
循环软化
,
拉伸保载
,
蠕变-疲劳
