On Factors Influencing Fatigue Process in Steel 316L Used in Hydrogen Energy Technologies (original) (raw)

Analysis of fatigue behaviour of stainless steels under hydrogen influence.PDF

Three stainless steels -ASTM 304, 316 and 316L -used in hydrogen utilization equipment are under investigation at conditions of tension-compression, rotating-bending and fretting fatigue. Fatigue tests are carried out with hydrogen charged and uncharged specimens. Hydrogen charging includes cathodic type of charging and exposure to high pressure hydrogen gas. The experiments under rotating bending and tensioncompression fatigue are conducted under different frequencies in three different laboratories: at . The fretting fatigue tests are presented by The HYDROGENIUS Institute at Kyushu University, Japan. The obtained results are presented in Wöhler curves complemented by plots "Short fatigue crack length-Number of cycles" and "Tangential force coefficient-Stress amplitude". The found fatigue characteristics are analyzed and compared at different loading conditions, showing the best performance of Steel 316L.

Analysis of fatigue behaviour of stainless steels under hydrogen influence

Fracture and Structural Integrity, 2016

Three stainless steels – ASTM 304, 316 and 316L - used in hydrogen utilization equipment are under investigation at conditions of tension-compression, rotating-bending and fretting fatigue. Fatigue tests are carried out with hydrogen charged and uncharged specimens. Hydrogen charging includes cathodic type of charging and exposure to high pressure hydrogen gas. The experiments under rotating bending and tensioncompression fatigue are conducted under different frequencies in three different laboratories: at The University of Chemical Technology and Metallurgy, Sofia, Bulgaria; at Sandia National Laboratory, California and The University of Tufts, Medford, Massachusetts, USA; The HYDROGENIUS Institute at Kyushu University, Japan. The fretting fatigue tests are presented by The HYDROGENIUS Institute at Kyushu University, Japan. The obtained results are presented in Wohler curves complemented by plots "Short fatigue crack length– Number of cycles" and “Tangential force coeffic...

Mathematical Analyses of Effect of Hydrogen on Fatigue Behaviour of Four Stainless Steels

2014

Fatigue in stainless steel-candidates for hydrogen storage and infrastructure is described mathematically at different loading conditions. The investigated steels are: EN10095 1.4301, EN10095 1.4401, EN10095 1.4404 and EN10095 1.4002. All the tests are carried out under tension-compression fatigue at different loads and a stress ratio R = −1. Specimens are machined in hour-glass shape with artificial hole from which initial cracks start their propagation. For finding the effect of hydrogen on fatigue behaviour of investigated steels, the specimens are divided into two groups: of hydrogen charged and uncharged ones. The obtained fatigue data of each steel are presented in plots “Crack length Number of cycles” and “Fatigue crack growth rate – Crack length”. A mathematical model is found for the data in the presentation “Fatigue crack growth rate – Crack length”. The model consists of double-parabolic-linear-curve for all steels, which makes it possible to prognosticate their fatigue b...

Hydrogen effects on low cycle fatigue of high strength steels

Materials Science and Technology, 2013

Hydrogen absorption occurs during steelmaking processes and causes detriment on mechanical properties, such as plasticity, fatigue strength and tensile strength, among others. The main purpose of the present paper is to study the hydrogen effects on the low cycle fatigue behaviour of a high strength steel, resulphurised and microalloyed. Before the cyclic tests, samples are cathodically charged using a H 2 SO 4 acid solution. In some samples, poisons are added. The flow stress evolution during cycling was studied by analysing the so called 'back' and 'friction' stresses derived from the hysteresis loops. Fatigued specimens were observed through scanning electron microscopy and transmission electron microscopy. Additionally, the metallographic technique known as 'silver decoration' allows evaluation of the hydrogen distribution in the structure by applying energy dispersive analysis. The higher stress levels and cyclic softening rates exhibited by hydrogen charged samples in comparison with uncharged ones are related with the friction stress behaviour. The hydrogen is found mainly associated with MnS inclusions.

Anomalies in hydrogen enhanced fatigue of a high strength steel

International Journal of Fatigue, 2014

Fatigue crack growth for an HSLA steel was studied with in situ hydrogen charging. The hydrogen effect was highest at low DK values. The anomalies in hydrogen effect were found in the relative insensitivity of the crack growth rates to DK in a decreasing DK test protocol, and in the distinct differences of the crack growth rates for different loading protocols. These anomalies are explained by the hydrogen availability at the crack tip as a function of the test parameters. A ''t'' and ''DK'' based parameter was found to be universally applicable for hydrogen enhanced fatigue irrespective of loading protocol.

A microstructural based understanding of hydrogen-enhanced fatigue of stainless steels

The microstructure immediately beneath the fracture surface produced during fully-reversed fatigue loading of uncharged and hydrogen-charged 304 and 316 stainless steels has been investigated by using focused ion beam machining in conjunction with transmission electron microscopy. The microstructure beneath striations on the fracture surface is dependent on the presence/absence of hydrogen and varies as a function of distance from the surface. The underlying microstructure also is dependent on the morphology of the fracture surface and is distinctly different beneath striations and flat regions. The differences in evolved microstructure are considered in terms of mechanisms by which hydrogen modifies deformation processes.

The effect of overload on the fatigue crack growth behaviour of 304 stainless steel in hydrogen

Fatigue <html_ent glyph="@amp;" ascii="&"/> Fracture of Engineering Materials and Structures, 2001

A B S T R A C T Fatigue crack growth (FCG) behaviour and its characteristics following tensile overloads were investigated for AISI 304 stainless steel in three different atmospheres; namely dry argon, moist air and hydrogen. The FCG tests were performed by MTS 810 servohydraulic machine. CT specimens were used for the tests and crack closure measurements were made using an extensometer. FCG rates of 304 stainless steel at both dry argon and moist air atmospheres have shown almost the same behaviour. In other words, the effect of moisture on FCG of this material is very small. However, in a hydrogen atmosphere, the material showed considerably higher crack growth rate in all regimes. In general, for all environments, the initial effect of overloads was to accelerate the FCG rate for a short distance (less than a mm) after which retardation occurred for a considerable amount of time. The main causes for retardation were found as crack blunting and a long reinitiation period for the fatigue crack. Regarding the environmental effect, the overload retardation was lowest in a hydrogen atmosphere. This low degree of retardation was explained by a hydrogen embrittlement mechanism. In a general sense, hydrogen may cause a different crack closure mechanism and hydrogen induced crack closure has come in to the picture. Scanning electron microscope and light microscope examinations agreed well with the above results.

Hydrogen Embrittlement Mechanism in Fatigue Behavior of Austenitic and Martensitic Stainless Steels

Metals

In the present study, the influence of hydrogen on the fatigue behavior of the high strength martensitic stainless steel X3CrNiMo13-4 and the metastable austenitic stainless steels X2Crni19-11 with various nickel contents was examined in the low and high cycle fatigue regime. The focus of the investigations were the changes in the mechanisms of short crack propagation. Experiments in laboratory air with uncharged and precharged specimen and uncharged specimen in pressurized hydrogen were carried out. The aim of the ongoing investigation was to determine and quantitatively describe the predominant processes of hydrogen embrittlement and their influence on the short fatigue crack morphology and crack growth rate. In addition, simulations were carried out on the short fatigue crack growth, in order to develop a detailed insight into the hydrogen embrittlement mechanisms relevant for cyclic loading conditions. It was found that a lower nickel content and a higher martensite content of the samples led to a higher susceptibility to hydrogen embrittlement. In addition, crack propagation and crack path could be simulated well with the simulation model.