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1

Prevention methods against hydrogen degradation of steel

Ćwiek J.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 43, nr 1

214-221

EN

Purpose: of this paper is presentation of mechanisms and forms of hydrogen degradation in steel along with pointing out methods for hydrogen degradation prevention. Design/methodology/approach: Hydrogen degradation of steel is a form of environmentally assisted failure which is caused by the action of hydrogen often in combination with residual or applied stress resulting in reduction of plasticity, load bearing capacity of a component, and cracking. Findings: The sources of hydrogen in steel were presented. Forms of hydrogen presence in metals, mechanisms of hydrogen degradation, and types of hydrogen induced damage were discussed in details. Five specific types of hydrogen induced damage to metals and alloys could be distinguished: hydrogen embrittlement, hydrogen-induced blistering, cracking from precipitation of internal hydrogen, hydrogen attack, cracking from hydride formation. Practical implications: Methods for hydrogen degradation prevention include: selection of suitable material, modifying environment to reduce hydrogen charging, and use of surface coatings and effective inhibitors. Originality/value: Originality the paper outlines the problem of hydrogen degradation of steel and other alloys, delivering knowledge to undertake preventive or remedial actions in order to avoid hydrogen induced degradation.

2

Evaluation of hydrogen degradation of high-strength weldable steels

Ćwiek J., Michalska-Ćwiek J.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 42, nr 1-2

103-110

EN

Purpose: of this paper is evaluation of susceptibility of a high-strength steel and welded joints to hydrogen degradation and establishing of applicable mechanism of their hydrogen embrittlement and hydrogen delayed cracking. Design/methodology/approach: High-strength quenched and tempered steel grade S690Q and its welded joints have been used. Susceptibility to hydrogen embrittlement of steel and welded joints has been evaluated using monotonically increasing load. Slow strain rate test (SSRT) was carried out in hydrogen generating environment, i.e. artificial sea water under cathodic polarization. Susceptibility to hydrogen delayed cracking has been evaluated under constant load in artificial sea water under cathodic polarization. Fractographic examinations with the use of scanning electron microscope (SEM) were performed to establish suitable mechanism of hydrogen-enhanced cracking. Findings: Tested high-strength steels and its welded joints are susceptible to hydrogen embrittlement when evaluated with the use of SSRT. The loss of plasticity is higher for welded joints then for the base metal. Tested steels and welded joints reveal high resistance to hydrogen degradation under constant load. Research limitations/implications: Further research should be taken to reveal the exact mechanism of crack initiation. Practical implications: Tested steel and its welded joints could be safely utilized in marine constructions under cathodic protection provided that overprotection does not take place. Tested steel could be safely utilized within elastic range of stress in hydrogen generating environments. Originality/value: Hydrogen-enhanced localized plasticity (HELP) model is more applicable mechanism of hydrogen degradation for tested steel and its welded joints under monotonically increasing load in seawater environment. Under the critical load and hydrogen concentration notched samples premature failed and hydrogen-enhanced localised plasticity (HELP) model is a viable degradation mechanism.

3

Hydrogen degradation of high-strength steels

Ćwiek J.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 37, nr 2

193-212

EN

Purpose: of this paper is to evaluate susceptibility of high-strength steels and welded joints to hydrogen degradation and to establish applicable mechanism of their hydrogen embrittlement and hydrogen delayed cracking. Design/methodology/approach: High-strength quenched and tempered steel grade S690Q and its welded joints have been used. Structural low-alloy steel 34CrAlNi7-10 with various plasma nitrided layers was evaluated. Susceptibility to hydrogen embrittlement of steel, welded joints, and nitrided layers was evaluated using monotonically increasing load. Slow strain rate test (SSRT) was carried out in hydrogen generating environments. Susceptibility to hydrogen delayed cracking was evaluated under constant load in artificial sea water. Fractographic examinations with the use of a scanning electron microscope (SEM) were performed to establish suitable mechanism of hydrogen-enhanced cracking. Findings: Tested high-strength steel and its welded joints are susceptible to hydrogen embrittlement when evaluated with the use of SSRT. The loss of plasticity is higher for welded joints then for the base metal. Tested steel and welded joints reveal high resistance to hydrogen degradation under constant load. Plasma nitrided layers are effective barriers for hydrogen entry into structural steel. Research limitations/implications: There has been no possibility to perform direct observations of exact mechanism of hydrogen-assisted cracking so far. Further research should be taken to reveal the exact mechanism of increased plasticity of a nitrided layer with absorbed hydrogen. Practical implications: Tested steel and its welded joints could be safely utilized within elastic range of stress in hydrogen generating environments, and constructions under cathodic protection provided that overprotection does not take place. Originality/value: Hydrogen-Enhanced Localized Plasticity (HELP) model is a more applicable mechanism of hydrogen degradation than the others for high-strength steels in hydrogen generating environments. Evidences of likely increased plasticity of nitrided layers with absorbed hydrogen were observed.

4

Effect of Al alloys microstructure on hydrogen permeation.

Łunarska E., Czerniajewa O., Zieliński A.

Inżynieria Materiałowa

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2001

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R. XXII, nr 4

568-571

EN

The distribution of hydrogen between the different states was estimated from hydrogen permeation and hydrogen extraction measurements and was correlated with the microstructure features of Al, Al-Cu-Mg-Mn (Dural), Al-Mg-Mn (Alustar) Al-Mg-Mn-Fe (PA13) and Al-Zn-Mg-Mn-Fe (PA47) alloys. Hydrogen lattice diffusivity was found to depend on the mean free paths between the main phase precipitate complexes. The content of reversibly trapped hydrogen correlated with the surface fraction of the main phase precipitates.

PL

Rozkład wodoru pomiędzy różnymi jego stanami w metalu oszacowano na podstawie pomiarów jego przenikania i ekstrakcji, oraz skorelowano z czynnikami mikrostruktury Al i stopów Al-Cu-Mg-Mn (Dural), Al-Mg-Mn (Alustar), Al-Mg-Mn-Fe (PA13) i Al-Zn-Mg-Mn-Fe (PA47). Stwierdzono, że szybkość dyfuzji sieciowej wodoru zależy od drogi swobodnego przebiegu pomiędzy konglomeratami cząstek głównej fazy wydzieleniowej. Stężenie wodoru, odwracalnie związanego z pułapkami koreluje ze stosunkową powierzchnią głównych wydzieleń fazowych.