Microstructural Aspects of Low Cycle Fatigue of Aged GX12CrMoVNbN9-1 Cast Steel

2013 ◽  
Vol 592-593 ◽  
pp. 708-711
Author(s):  
Stanisław Mroziński ◽  
Grzegorz Golański ◽  
Krzysztof Werner
Keyword(s):  
Low Cycle Fatigue ◽  
Cast Steel ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Fatigue Tests ◽  
Total Strain Amplitude ◽  
Cycle Fatigue ◽  
Transmission Electron Microscopy Study ◽  
Transmission Electron ◽  
The Matrix

The paper presents the results of research on the changes in microstructure of GX12CrMoVNbN9-1 cast steel subject to aging at the temperature of 600°C and holding time of 8000 hours, followed by low-cycle fatigue. The characteristics of the microstructure of the examined cast steel after ageing and low-cycle fatigue was described using transmission electron microscopy (study of the dislocation microstructure) and morphology of precipitations. It has been shown that low cycle fatigue leads to the matrix softening as a result of the processes of recovery, polygonization and repolygonization. Moreover, the processes of precipitation of Laves phase and coagulation of M23C6 carbides were observed in the microstructure. Intensity of these processes depended not only on the temperature of fatigue tests, but also on the level of total strain amplitude εac.

Evolution of Microstructure in Martensitic GX12CrMoVNbN9 – 1 Cast Steel after Low Cycle Fatigue

2013 ◽  
Vol 199 ◽  
pp. 418-423
Author(s):  
Grzegorz Golański ◽  
Joanna Kępa
Keyword(s):  
Low Cycle Fatigue ◽  
Cast Steel ◽  
Total Strain Amplitude ◽  
Cycle Fatigue ◽  
Tempered Martensite ◽  
Transmission Electron ◽  
The Matrix ◽  
The Mean ◽  
Means Of Transmission ◽  
Evolution Of Microstructure

The paper presents the results of microstructural research on GX12CrMoVNbN91 cast steel in the as-received condition (after heat treatment) and after the process of low cycle fatigue at room temperature. The microstructural tests were carried out by means of transmission electron microscope and completed with quantitative study determining: the mean diameter of subgrains, density of dislocations and shape factor. Performed research has proved that in both states: the as-received one, as well as after fatigue, the investigated cast steel is characterized by lath microstructure of tempered martensite with numerous precipitations of the M23C6 and MX type. Fatigue in the low cycle scope leads to the processes of recovery and polygonization of the matrix, as a result of a decrease in the dislocation density and an increase in the subgrain width. Intensity of these processes depends not only on the temperature of testing, but also on the level of total strain amplitude εac. Stability of the substructure of the examined cast steel depends on the morphology of precipitates of M23C6, precipitated on the boundaries of grains/subgrains.

Newly formed phyllosilicates in rock matrices and fractures from CRP-3 core (Antarctica): an electron microscopy study

Clay Minerals ◽  
2007 ◽  
Vol 42 (1) ◽  
pp. 21-43 ◽  
Author(s):  
G. Giorgetti ◽  
F. S. Aghib ◽  
K. J. T. Livi ◽  
A.-C. Gaillot ◽  
T. J. Wilson
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Marine Sediments ◽  
Ross Sea ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Secondary Phases ◽  
Transmission Electron Microscopy Study ◽  
Transmission Electron ◽  
The Matrix

AbstractA scanning and transmission electron microscopy study has been performed on Oligocene glacio-marine sediments, Devonian sandstones, and Jurassic dolerites recovered during CRP-3 drilling in the Ross Sea (Antarctica). Newly formed clay minerals occur in the rock matrices and as fillings in veins and faults which crosscut the whole sequence. Authigenic clays in sediments consist of beidellite-montmorillonite, berthierine/chlorite intergrowths and illite. Al,K-rich smectites and kaolinite occur in the Devonian sandstones. Saponite, berthierine/chlorite intergrowths, and Fe-hydroxides develop in the altered dolerites. Hence, the composition of the secondary phases depends also on the geochemistry of the rock they grow in. Within each sample, the same authigenic minerals form in the matrix and in the vein/fault. Clays precipitated from fluids, with variable fO2 values, which circulated in the system during the contemporaneous diagenetic and faulting events.

Low Cycle Fatigue Behaviour of GX12CrMoVNbN9 -1 Cast Steel at Room Temperature

2011 ◽  
Vol 291-294 ◽  
pp. 1106-1109 ◽  
Author(s):  
Grzegorz Golański ◽  
Krzysztof Werner ◽  
Stanisław Mroziński
Keyword(s):  
Heat Treatment ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Cast Steel ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Total Strain Amplitude ◽  
Cycle Fatigue ◽  
Number Of Cycles ◽  
Stabilization Period

The report treats of the low cycle fatigue (LCF) behaviour of GX12CrMoVNbN9-1 (GP91) cast steel after heat treatment (1040°C/12h/oil + 760°C/12h/air + 750°C/8h/furnace). Fatigue tests were carried out at room temperature for five levels of the controlled total strain amplitude εac = 0.25, 0.30, 0.35, 0.50 and 0.60 %. The research performed within the scope of LCF has shown in general that the investigated cast steel was subject to strong cyclic weakening, revealing no stabilization period at the same time. At the final stage of fatigue there was quick weakening of the material which proceeded till its destruction. The growth of amplitude εac resulted in reducing the number of cycles till the destruction stage.

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