Hydrogen Assisted Fatigue Crack Growth in a Precipitation-Hardened Martensitic Stainless Steel Under Gaseous Hydrogen

Abstract

In this study, the effect of gaseous hydrogen on the fatigue crack growth behavior in a precipitation-hardened martensitic stainless steel is investigated. It is known that the degradation in fatigue crack growth behavior derives from a complex interaction between the fatigue damage and the amount of hydrogen enriching the crack tip, which is dependent on the hydrogen pressure, loading frequency, and stress intensity factor amplitude. Therefore, fatigue crack growth tests were performed in a range of 0.09 to 40 MPa under gaseous hydrogen at a frequency of 20 and 0.2 Hz. The fatigue data as well as fracture morphologies obtained so far indicate a sharp increase in crack growth rates in a narrow range of stress intensity factor amplitudes. Also, it is shown that by decreasing the loading frequency to 0.2 Hz at a given pressure of hydrogen the transition occurs at lower values of stress intensity factor amplitudes accompanied by a change in fracture mode. Scanning electron microscope (SEM) observations of the fracture surfaces are used to support the explanations proposed to account for the observed phenomena.

Reliability Estimation of Transport Means Elements Under the Action of Cyclic Loads and Corrosive Environment

“…Nowadays, up to 65% of the mechanisms of transport means elements are known to get out of order under the influence of aggressive (corrosive) environment and mechanical stresses; up to 25% of these mechanisms are broken down due to the overloads caused by strength losses because of corrosion damages [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. According to the data on agrarian production development in Ukraine, the growth of the transportation volumes of chemical and mineral fertilizers [15] is about 2% of all cargoes.…”

“…The percentage of failures ranges from 50% to 80% [1][2][3]. The most characteristic failures of the undercarriages are the cracks in frames, spar and cross bars [1][2][3]. The analysis of the reasons due to which steel structures enter the failure state became it possible to draw a conclusion on the causal complex of events that lead to failure.…”

“…Delayed spontaneous fracture of structural elements under the action of variable in time (cyclic) loads and corrosive-aggressive environments is relatively continuous but dangerous process because of the low degree of its predictability and diagnosis. Corrosive environments increase the failure probability of metal materials [1][2][3][4][5] during cyclic loading and cause the propagation of corrosion-fatigue cracks. To determine the service life of vehicles constructions elements under the influence of cyclic loads and corrosive environments, the appropriate analytical models should be applied.…”

Controlling factors and mechanisms of fatigue crack growth influenced by high pressure of gaseous hydrogen in a commercially pure iron

“…Fatigue Crack Growth (FCG) tests were conducted under high pressure of hydrogen gas at various frequencies in order to make the exposure of the crack tip to hydrogen gas vary and evaluate the impact on crack growth resistance. The experimental details, the test results and observations are reported in [25][26][27] and will be only briefly summarized here. The main purpose of the present paper is to provide a detailed discussion of these findings by integrating the different facts and associated insights.…”

“…The dislocation structure observed within this very limited area is typically related to a single grain with a given orientation, grain size, and so on. Ogawa et al [24,25] additionally provide the Grain Reference Orientation Deviation (GROD) mapping near the crack path by means of the EBSD analysis so as to analyze the plastic strain distribution in the scale of hundred microns. The results indicate that the extent of plastic strain distribution near the intergranular crack path in hydrogen is almost the same as in air, and in any case not clearly greater.…”