Effects of MnS Inclusion Dissolution on Environmentally Assisted Cracking in Low-Alloy and Carbon Steels

Hänninen, Hannu; Cullen, W.H.; Kemppainen, M.

doi:10.5006/1.3585150

Cited by 33 publications

(13 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, typical fan-like or quasi-cleavage patterns were frequently observed around or near the sulfide inclusions (Figs. 11e and 11f), which were very similar to the hydrogen-induced cracking features observed in hydrogencharged steels [22,23] or in stress corrosion cracking (SCC) tests [24,25]. The above results suggested that sulfide inclusions, combined with hydrogen-induced cracking, may play a key role in the EAC in high temperature water.…”

Section: Fatigue Cracking/fractographic Morphologiessupporting

confidence: 70%

Inclusion‐involved fatigue cracking in high temperature water

Katada

2005

Materials & Corrosion

View full text Add to dashboard Cite

The nonmetallic inclusions in low-alloy pressure vessel steel A533B were carefully examined and the low cycle fatigue (LCF) behavior of the steel was investigated in 288 8C air and water. Much attention was paid to the roles of inclusions on fatigue crack initiation and propagation in high temperature water. Three types of inclusions were observed in the steel, consisting of isolated or clustered sulfide inclusions, duplex oxide-sulfide inclusions and isolated oxide inclusions. In high temperature air, fatigue cracks initiated predominantly from subsurface inclusions. In high temperature water, however, fatigue cracks initiated primarily at corrosion pits on the specimen surfaces resulted mainly from the dissolution of large or clustered sulfide inclusions. The subsurface and bulk inclusions also contributed to the fatigue cracking in high temperature water. Possible influence of the above three types of inclusions on environmentally assisted cracking (EAC) was evaluated. The fatigue fractographic features suggested a synergism between sulfide inclusions and hydrogen-induced cracking dominate the present EAC in high temperature water.

show abstract

Section: Fatigue Cracking/fractographic Morphologiessupporting

confidence: 70%

Inclusion‐involved fatigue cracking in high temperature water

Katada

2005

Materials & Corrosion

View full text Add to dashboard Cite

show abstract

“…[1][2][3][4][5] Broomfield's calculated result has shown that up to 2 ppm of hydrogen can be easily absorbed in pressure vessel steels from corrosion reactions, [4] while the analysis of Westinghouse predicted the hydrogen concentration to be three times this value in a reactor vessel steel after prolonged shutdown. [5] In addition, according to the measurements of Hänninen et al, [6] about 3.5 to 4.9 ppm hydrogen still remained in gage length of the prefatigued A533B low-alloy steel specimens after slow strain rate testing in the PWR water (under 0.0 V SHE applied potential), even though the measurements were carried out more than half a year after the actual testing and there was plenty of time for hydrogen to diffuse out of the specimens. Another possible hydrogen source may be hydrogen water chemistry (HWC), which has been used as a remedial measure to protect the BWR structural components against intergranular stress corrosion cracking.…”

Section: Introductionmentioning

confidence: 97%

Hydrogen-involved tensile and cyclic deformation behavior of low-alloy pressure vessel steel

Katada

Kim

et al. 2004

Metall Mater Trans A

View full text Add to dashboard Cite

The temperature-and strain-rate-dependent tensile behavior of hydrogen-charged low-alloy pressure vessel steel ASTM A508 C1.3 has been investigated. The fatigue crack initiation and propagation behavior of the steel in high-temperature water environments has also been evaluated. It was found that hydrogen played significant roles in both tensile and cyclic deformation processes, especially in the temperature and strain-rate region of dynamic strain aging (DSA). The presence of hydrogen resulted in a distinct softening in tensile strength and a certain loss in tensile ductility in the DSA region. Remarkable degradation in fatigue crack initiation and propagation resistance in high-temperature water environments was observed in the DSA strain-rate region. Typical hydrogen-induced cracking features also appeared on the corresponding fatigue fracture surfaces. The interactions between hydrogen and DSA in tensile and cyclic deformation processes are discussed as well as their combined effects on the environmentally assisted cracking (EAC) mechanism of pressure vessel steels in high-temperature water environments.

show abstract

“…For this set of experiments the detectors were positioned to measure 32 observed using tritium autoradiography in cathodically charged samples, [36][37][38] our data provide direct evidence that these inclusions trap hydrogen in gaseous environments as well. Further longer term exposure studies would be required on higher S content alloys to observe if the idea proposed by Hanninen 9,10 postulating that MnS inclusions act as hydrogen trap sites in low alloy steels and their subsequent dissolution in aqueous environments (as was recently directly observed through in situ TEM/EDS examination) 39 changes crack tip electrochemistry and enhances hydrogen absorption also holds in gaseous environments.…”

Section: Resultsmentioning

confidence: 99%

“…[1][2][3][4] In particular, the contribution of hydrogen to the acceleration of fatigue failure is well-documented. [5][6][7][8][9][10] Several mechanisms of hydrogen-assisted cracking (HAC) of steels have been postulated, including the longstanding decohesion theory introduced by Troiano 11,12 and Oriani, 3,13 and the hydrogen-assisted deformation mechanism first proposed by Beachem 14 and verified by Birnbaum et al [15][16][17] using in situ transmission electron microscopy (TEM) straining experiments in H 2 . Birnbaum and Sofronis 18 further developed these concepts into the hydrogen-enhanced localized plasticity (HELP) mechanism.…”

Section: Introductionmentioning

confidence: 99%

High resolution NanoSIMS imaging of deuterium distributions in 316 stainless steel specimens after fatigue testing in high pressure deuterium environment

2018

View full text Add to dashboard Cite

It is irrefutable that the presence of hydrogen reduces the mechanical performance of many metals and alloys used for structural components. Several mechanisms of hydrogen-assisted cracking (HAC) of steels have been postulated. The direct evidence of the mechanisms by which hydrogen embrittles these materials has remained elusive. This is by virtue of our difficulty to directly observe the hydrogen distribution at spatial resolutions less than 100 nm and analysis volumes greater than 1 × 10 9 atoms at microstructural features such as grain boundaries, dislocations, twins, stacking faults and sub-micron inclusions that are all potential hydrogen trapping sites postulated to be responsible for the degradation of mechanical performance. Here, we report on an experimental methodology combining an elaborate fatigue testing protocol in an enriched gaseous deuterium environment with NanoSIMS (secondary ion mass spectrometry) imaging for detection of deuterium at spatial resolutions as low as 100 nm and accompanying TEM analysis. Type 316 stainless steel compact tension specimens were precharged in deuterium followed by fatigue testing at high stress ratio (0.7), low delta K (~11 MPa √m), and a frequency of 1 cycle per minute using a sawtooth waveform with a rise time of 30 s in high pressure (68.9 MPa) gaseous deuterium (99.999% purity) environment at room temperature. High resolution NanoSIMS imaging was then used to measure the deuterium distribution at the tip of and in the wake of secondary and tertiary fatigue cracks as well as at MnS inclusions. The use of deuterium eliminates the difficulties of interpreting hydrogen measurements by SIMS relating to the ubiquitous presence of hydrogen in all high vacuum systems and guarantees that deuterium measured by the NanoSIMS must be attributed to the fatigue testing protocol. This methodology has allowed us to directly observe the distribution of hydrogen in dislocation tangles ahead and in the wake of fatigue crack tips and at the interface of MnS inclusions. The protocol provides an avenue by which the path and speed with which hydrogen proceeds along its embrittling course of action may be directly followed through modifications of the fatigue testing parameters and/or alloy type and allows a means to validate at least qualitatively recently published models of enhanced hydrogen transport by dislocations.npj Materials Degradation (2018) 2:2 ;

show abstract

Effects of MnS Inclusion Dissolution on Environmentally Assisted Cracking in Low-Alloy and Carbon Steels

Cited by 33 publications

References 0 publications

Inclusion‐involved fatigue cracking in high temperature water

Inclusion‐involved fatigue cracking in high temperature water

Hydrogen-involved tensile and cyclic deformation behavior of low-alloy pressure vessel steel

High resolution NanoSIMS imaging of deuterium distributions in 316 stainless steel specimens after fatigue testing in high pressure deuterium environment

Contact Info

Product

Resources

About