Posouzení náchylnosti vybraných materiálů k vodíkovému křehnutí
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Date
2025-06-10
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Abstract
Tato diplomová práce je zaměřena na výběr materiálů vhodných pro použití v rotačních částech turbostrojů, konkrétně rotorů elektromotorů, které musí vykazovat vysokou mechanickou pevnost a dostatečnou houževnatost za provozních podmínek. Specifickým požadavkem je zároveň odolnost vůči působení vodíku, který se může v reálném provozu vyskytovat. Z tohoto důvodu byla hlavní pozornost věnována problematice vodíkové křehkosti u vysokopevnostních ocelí 31CrMoV9, 42CrMo4 a Imacro M.
Součástí práce bylo navržení, realizace a ověření dvou metod sycení vodíkem - v tlakové plynné atmosféře a elektrochemickém prostředí. Tyto metody byly zvoleny s cílem simulovat jak reálné provozní podmínky, tak zrychlené laboratorní stárnutí materiálu. Vzhledem k nemožnosti přesného stanovení koncentrace vodíku v materiálu byly mechanické vlastnosti hodnoceny porovnáním sycených a nesycených vzorků. Pro tento účel byly provedeny tahové a rázové zkoušky, doplněné fraktografickou analýzou.
Získané výsledky umožnily posoudit náchylnost jednotlivých materiálů k vodíkové křehkosti a posloužily k výběru nejvhodnějšího materiálu pro danou aplikaci. Zároveň byla ověřena použitelnost navržené metodiky pro budoucí hodnocení podobných konstrukčních materiálů.
This thesis investigates the selection of materials suitable for use in rotating components of turbomachinery, specifically the rotors of electric motors, which are required to exhibit high mechanical strength and sufficient toughness under operational conditions. An additional critical requirement is resistance to hydrogen exposure, which may occur during real-life service. Therefore, the work focuses specifically on hydrogen embrittlement in high-strength steels 31CrMoV9, 42CrMo4, and Imacro M. The experimental part of the thesis was primarily aimed at developing, implementing, and validating two distinct hydrogen charging methodologies - high-pressure gaseous exposure and electrochemical charging - under controlled conditions. These approaches were chosen to simulate both real operational environments and accelerated laboratory-induced material aging. Since the exact amount of absorbed hydrogen could not be reliably quantified, the impact of hydrogen exposure was evaluated through comparative testing of charged and uncharged specimens. To this end, tensile and impact tests were conducted, and the resulting fracture surfaces were examined using fractographic analysis. The results enabled a comparative assessment of the susceptibility of the tested materials to hydrogen embrittlement and provided a basis for identifying the most suitable candidate for the intended application. Furthermore, the developed experimental methodology was confirmed to be applicable for future evaluation of similar structural materials in hydrogen-related environments.
This thesis investigates the selection of materials suitable for use in rotating components of turbomachinery, specifically the rotors of electric motors, which are required to exhibit high mechanical strength and sufficient toughness under operational conditions. An additional critical requirement is resistance to hydrogen exposure, which may occur during real-life service. Therefore, the work focuses specifically on hydrogen embrittlement in high-strength steels 31CrMoV9, 42CrMo4, and Imacro M. The experimental part of the thesis was primarily aimed at developing, implementing, and validating two distinct hydrogen charging methodologies - high-pressure gaseous exposure and electrochemical charging - under controlled conditions. These approaches were chosen to simulate both real operational environments and accelerated laboratory-induced material aging. Since the exact amount of absorbed hydrogen could not be reliably quantified, the impact of hydrogen exposure was evaluated through comparative testing of charged and uncharged specimens. To this end, tensile and impact tests were conducted, and the resulting fracture surfaces were examined using fractographic analysis. The results enabled a comparative assessment of the susceptibility of the tested materials to hydrogen embrittlement and provided a basis for identifying the most suitable candidate for the intended application. Furthermore, the developed experimental methodology was confirmed to be applicable for future evaluation of similar structural materials in hydrogen-related environments.
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Vodíková křehkost, sycení plynným vodíkem, elektrochemické nabíjení vodíkem, degradace mechanických vlastností, DEMO mechanických vlastností, tlaková komora