Teplotní efekt na cyklické napěťové komponenty superslitiny Inconel 738LC

Effect of Temperature on cyclic stress components of Inconel 738LC superalloy

článek ve sborníku ve WoS nebo Scopus

en

Multiple step tests in strain control havebeen performed on cylindrical specimens of cast polycrastalline Inconel 738LC superalloy at 23, 500 and 800 C in laboratory atmosphere to study the effect of temperature on the internal and effective cyclic stress components. At these temperatures, the evolution of the effective and internal stress components and effective elastic modules were derived from the hysteresis loops which were analysed according to the statistical theory of hysteresis loop. Cyclic hardening/softening curves and shortened cyclic stress-strain curves were obtained at three temperatures. Cyclic hardening/softening behaviour depends both on temperature and strain amplitude. Low amplitude straining was characterized by saturation of the stress amplitude. In high amplitude straining a pronounced hardening was found at room temperature and at 500 C. Saturated behaviour was found at temperature 800 C. The shortened cyclic stress-strain curves can be fitted by power law at three temperatures. They are shifted to lower stresses with increasing temperature. Observation of the surface revealed cyclic strain localization into persistent slip bands at all three temperatures. Cyclic stress-strain response is compared at all temperatures and discussed in relation to changes if internal and effective stress components and microstructural parameters of the material.

Zkouška se stupňovitým nárůstem amplitudy celkové deformace byla provedena na válcových zkušebních tyčích z lité polykrystalické slitiny Inconel 738LC při teplotách 23, 500, 800 C na vzduchu za účelem studia efektu teploty na interní a efektivní komponenty cyklického napětí. Při těchto teplotách byl vývoj efektivních a interních napěťových komponentů a efektivních elastických modulů zjištěn z derivací hysterezních smyček. Také byly naměřeny křivky cyklickéhé zpevnění/ změkčení a zkrácené cyklické deformační křivky.

Multiple step tests in strain control havebeen performed on cylindrical specimens of cast polycrastalline Inconel 738LC superalloy at 23, 500 and 800 C in laboratory atmosphere to study the effect of temperature on the internal and effective cyclic stress components. At these temperatures, the evolution of the effective and internal stress components and effective elastic modules were derived from the hysteresis loops which were analysed according to the statistical theory of hysteresis loop. Cyclic hardening/softening curves and shortened cyclic stress-strain curves were obtained at three temperatures. Cyclic hardening/softening behaviour depends both on temperature and strain amplitude. Low amplitude straining was characterized by saturation of the stress amplitude. In high amplitude straining a pronounced hardening was found at room temperature and at 500 C. Saturated behaviour was found at temperature 800 C. The shortened cyclic stress-strain curves can be fitted by power law at three temperatures. They are shifted to lower stresses with increasing temperature. Observation of the surface revealed cyclic strain localization into persistent slip bands at all three temperatures. Cyclic stress-strain response is compared at all temperatures and discussed in relation to changes if internal and effective stress components and microstructural parameters of the material.

Nizko-cyklová únava; superslitina; vysoké teploty; hysterezní smyčka; efektivní a interní napětí

Low cycle fatigue; superalloy; high temperatures; hysteresis loop; effective and internal stresses

2008

02.09.2008

VUTIUM

Brno

9781617823190

Proceedings of 17th European Conference on Fracture

1358–1365

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