National Repository of Grey Literature 45 records found  beginprevious35 - 44next  jump to record: Search took 0.00 seconds. 
Nízkocyklová únava INCONELu 792-5A při 900 °C
Petrenec, Martin ; Obrtlík, Karel ; Man, Jiří ; Polák, Jaroslav
The aim of the present paper is to investigate the low cycle fatigue characteristics of cast nickel base superalloy INCONEL 792-5A in symmetrical total strain cycling at the temperature 900 °C.
Initial stages of fatigue failure of polycrystalline materials
Man, Jiří ; Petrenec, Martin ; Obrtlík, Karel ; Polák, Jaroslav
Geometry of persistent slip markings (PSMs) formed during cyclic loading of polycrystalline stainless steels and superalloy was studied using atomic force microscopy (AFM) and high-resolution scanning electron microscopy (SEM-FEG). Internal dislocation structure was investigated using transmission electron microscopy (TEM). Persistent slip bands with dislocation structure corresponding to the cyclic strain localization were identified and correlated with PSMs observed on the specimen surface.
Quantitative assessment of the surface relief in fatigue using AFM
Man, Jiří ; Obrtlík, Karel ; Polák, Jaroslav
Atomic force microscopy (AFM) was applied to study the early stages of fatigue damage in polycrystalline copper and stainless 316L steel. The analysis of the image formation using an AFM tip reveals the lateral distortion of the extrusions and intrusions in case of high extrusions and deep intrusions. The true extrusion height can be obtained in direct observation and the depth of intrusions using replica technique. The evolution of the shape and the height of extrusions allowed to judge the activity of the persistent slip bands (PSBs) during fatigue life.
Effect oc surface carburizing on low cycle fatigue of 316L austenitic stainless steel
Obrtlík, Karel ; Polák, Jaroslav
Both surface carburized and untreated 316L stainless steel specimens were cyclically loaded with constant plastic strain amplitude. Characteristics of stress strain response and fatigue life were evaluated and surface relief evolution and crack initiation was studied.
Factors determining lifetime of single crystalline gas turbine blades
Lukáš, Petr ; Kunz, Ludvík ; Obrtlík, Karel ; Čadek, Josef
Creep, low-cycle fatigue and creep/fatigue tests were performed on Nickel base superalloy CMSX-4 at high temperatures. It has been shown that the crystal orientation has a strong influence on creep and low-cycle fatigue resitance. Results of creep/fatigue experiments show that small vibrations exhibit a beneficial effect on creep rate.
Fatigue life and short crack growth in plasma nitrided 316L stainless steel
Obrtlík, Karel ; Polák, Jaroslav
Cylindrical specimens with shallow notch of 316L austenitic stainless steel both with plasma nitrided and untreated surface were cyclically strained with constant plastic strain amplitude. Fatigue life, crack initiation, short crack growth and stress response were studied in both materials.

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