A.Scholz
,
A.Schmidt
,
A.Samir
,
C.Berger
金属学报(英文版)
The thermomechanical fatigue behaviour of different high temperature alloys has been investigated and is under investigation respectively. The creep-fatigue behaviour of heat resistant steels was investigated by long-term service-type strain cycling tests simulating thermomechanical fatigue (TMF-) loading conditions at the heated surface of e.g. turbine rotors. Single-stage as well as three-stage cycles leads to similar results at the application of the damage accumulation rule. Life prediction which simulates typical combinations of cold starts, warm starts and hot starts has been established successfully for isothermal service-type loading and will be exceeded for thermomechanical loading. Long-term thermomechanical fatigue testing of Thermal Barrier Coating systems show typical delamination damage. An advanced TMF cruciform testing system enables complex multiaxial loading.
关键词:
thermomechanical fatigue
,
null
,
null
R.Bardenheier
,
G.Rogers
金属学报(英文版)
Two different types of experimental techniques to perform non-isothermal, uniaxial and biaxial fatigue tests were described. A new miniaturised electrothermalmechanical test rig was presented and discussed. It enables testing of small specimens under complex thermomechanical loading conditions. In order to cope with the simulation of well defined biaxial proportional and non-proportional loadings with in-phase and out-of-phase superposition of thermal loads a cruciform biaxial fatigue testing machine has been developed. Special design features of both machines, and the specimens tested, as well as typical test results were discussed.
关键词:
thermomechanical fatigue
,
null
,
null
肖慧
,
李晓延
,
陈健
,
雷永平
,
史耀武
稀有金属材料与工程
对热循环条件下SnAgCu/Cu焊点的热力疲劳行为进行了研究.基于热循环条件下实际倒装焊点的位移分析,设计了单焊点试样及其热力耦合加载装置.利用电阻应变测量法研究了-40～125℃热循环条件下焊点的变形行为.以电阻变化率为损伤参量,确定了焊点的损伤演变规律以及焊点热疲劳寿命.基于此,采用基于应变的Coffin-Manson模型确定了焊点寿命与非弹性应变之间的关系.结果表明焊点随加载应变范围的增大而出现加速破坏.最后,对热循环过程中SnAgCu/Cu焊点的微观组织演变进行了扫描电镜观察分析,旨在进一步揭示焊点失效的本质.
关键词:
SnAgCu/Cu焊点
,
热力耦合疲劳
,
失效行为
,
热循环
陈继光
,
邓文凯
,
周萍
,
江亮
中国有色金属学报
基于热机械疲劳试验,建立IN718高温合金感应加热过程中电磁场和温度场耦合的数学模型,对试样在循环加热条件下的非稳态温度场进行仿真,采用电子背散射衍射技术对试样上的晶粒尺寸进行检测并对其数据进行统计分析.结果表明:综合传热系数和风机电压呈正相关的关系;试样径向上存在温度梯度且随时间变化,最大温差为5℃左右,符合试验要求;低周疲劳试样径向上不同点的平均晶粒尺寸均有所增长,且增长幅度基本相同;由于温度梯度的影响,热机械疲劳试样径向上的晶粒尺寸分布不均匀,中心位置和表面位置的平均晶粒尺寸增长幅度分别为16.94%和5.3%.
关键词:
高温合金
,
热机械疲劳
,
感应加热
,
温度梯度
,
晶粒尺寸
