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Low cycle fatigue of ferritic ductile cast iron with alloying nickel
Tesařová, H. ; Petrenec, Martin ; Pacal, B.
Total strain controlled tests have been performed on cylindrical specimens of ductile cast iron with aim to assess of the fatigue resistance. Cyclic hardening, cyclic stress-strain and fatigue life curves were obtained. The microstructure is documented using light microscope. Fracture surface was studied using scanning electron microscopy. Manson-Coffin and Basquin laws can reasonably approximate the fatigue life data. Fatigue crack initiation close to the surface is documented.
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Low cycle fatigue on Inconel 713L and Inconel 792-5A superalloys at 500 A 700 °C
Petrenec, Martin ; Obrtlík, Karel ; Polák, Jaroslav ; Hrbáček, K. ; Kruml, Tomáš
Cylindrical specimens of cast polycrystalline nickel base superalloys Inconel 713LC and 792-5A were cyclically strained under total strain control at500°C and at700°C.Structural characteristics and morphology of gama´ precipitates of both materials are documented. Dislocations structures were studied using transmission electron microscopy using technique of oriented foils in selected specimens cyclically strained up to failure. Cyclic hardening/softening curves, cyclic stress-strain curves, and fatigue life curves were obtained for both temperatures. Cyclic hardening/softening curves depend both on temperature and plastic strain amplitude. The cyclic stress-strain curves can be approximated by power law. Experimental points of fatigue life curves satisfy the Manson-Coffin and Basquin law. Stress-strain response and fatigue life characteristics are compared at both temperatures and discussed in relative to structural parameters and to dislocation structures of superalloys studied.
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Fatigue behaviour of nickel base superalloy Inconel 738LC at room temperature
Juliš, M. ; Obrtlík, Karel ; Petrenec, Martin ; Podrábský, T.
Total strain controlled tests have been performed on cylindrical specimens of Inconel 738LC polycrystals at room temperature (23 °C). Cyclic hardening, cyclic stress-strain and fatigue life curves were obtained. Fracture surface was studied using scanning electron microscopy. High amplitude cycling results in early pronounced hardening followed by secondary hardening. Low amplitude cycling is characterized by the stable stress response. Manson-Coffin and Basquin laws can reasonably approximate the fatigue life data. Fatigue crack initiation close to the surface from casting defects is documented.
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Comparison of low cycle fatigue characteristics of cast nickel base superalloys Inconel 713 LC a Inconel 792-5A
Petrenec, Martin ; Obrtlík, Karel ; Polák, Jaroslav
Cylindrical specimens of cast polycrystalline nickel base superalloys Inconel 713 LC and Inconel 792-5A were cyclically strained under total strain control at room temperature and at 800 °C. Structural characteristics of both materials are documented. Metallographic observations revealed coarse grains with dendrites, shrinkage pores and carbide inclusions. TEM observation shows differences in the morphology of ordered γ´ precipitates in both materials. Cyclic hardening/softening curves, cyclic stress-strain curves, and fatigue life curves were obtained for both temperatures. The cyclic hardening/softening curves depend both on temperature and plastic strain amplitude. The cyclic stress-strain curves can be approximated by power law. Experimental points of fatigue life curves satisfy the Manson-Coffin and Basquin law. Stress-strain response and fatigue life characteristics are compared at both temperatures and discussed in relation to structural parameters of materials studied.
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Fatigue behaviour of nickel base superalloy Inconel 713LC at high temperature
Juliš, M. ; Obrtlík, Karel ; Podrábský, T. ; Petrenec, Martin
Total strain controlled tests have been performed on cylindrical specimens of Inconel 713 LC polycrystals at 800 °C. Cyclic hardening-softening, cyclic stress-strain and fatigue life curves were obtained. Fracture surface was studied using scanning electron microscopy. High amplitude cycling results in early pronounced hardening followed by softening. Low amplitude cycling is characterized by the stable stress response. Manson-Coffin and Basquin laws can reasonably approximate the fatigue life data. Fatigue crack initiation at casting defects is documented.
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Material analysis of magnesium alloy AZ 91 with various amount of lithium
Man, O. ; Petrenec, Martin ; Ptáček, L.
he contribution deals with magnesium alloy of commercial grade AZ 91 with various amount of lithium addition (5.5, 8 and 12 wt.%). The alloy was observed in the as-cast state and after annealing. Various types of analysis were done, such as metallographic one using light microscopy, scanning electron microscopy and transmision electron microscopy, in order to gain knowledge about the phase composition of the alloy and its development. Several phases and morphological features were identified, but the rest was not, due to the properties of lithium-rich areas.
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