Hydrogen-induced Cracking Research Articles

Effects of heterogeneous plastic strain on hydrogen-induced cracking of twinning-induced plasticity steel: A quantitative approach

Heterogeneous plastic strain is essential for understanding hydrogen-induced crack (HIC) initiation in twining-induced plasticity (TWIP) steel with relatively no microtexture. In this study, electron backscattered diffraction technology was used to quantitatively characterize the heterogeneous plastic strain after a slow strain rate test with hydrogen charging, and the deformation mode and HIC initiation mechanism were clarified. From a statistical analysis of more than 100 grain boundaries, the cracked grain boundary and its vicinity have high heterogeneous strain; that is, the geometrically necessary dislocation density is high, and vice versa. Therefore, high strain incompatibility is the key factor for HIC initiation.

Hydrogen Trapping in Laser Powder Bed Fusion 316L Stainless Steel

In this study, the hydrogen embrittlement (HE) of 316L stainless steel produced by laser powder bed fusion (L-PBF) was investigated by means of hydrogen trapping. The susceptibility of the material to HE is strongly connected to the interaction of hydrogen atoms with volumetric defects in the material. Trapping hydrogen in those defects affects its availability to critical locations where a hydrogen-induced crack can nucleate. Therefore, it is important to study the characteristics of hydrogen traps to better understand the behavior of the material in the hydrogen environment. The hydrogen was introduced into the material via electrochemical charging, and its interactions with various trapping sites were studied through thermal desorption spectroscopy (TDS). The obtained results were compared to conventionally produced 316L stainless steel, and the correlation between microstructure, characteristics of hydrogen traps, and susceptibility to HE is discussed.

Application of Molecular Dynamics Calculations to Elucidation of the Mechanism of Hydrogen-Induced Crack Initiation in Fracture Toughness Tests Using Tempered Martensitic Steels

Application of Molecular Dynamics Calculations to Elucidation of the Mechanism of Hydrogen-Induced Crack Initiation in Fracture Toughness Tests Using Tempered Martensitic Steels

In Situ Investigation of Hydrogen-Induced Cracking Behavior in Linepipe Steel Under Different Environments

NACE MR0175/ISO 15156 provides the severity of a sour environment defined as a function of pH and H2S partial pressure for sulfide stress cracking. Although hydrogen-induced cracking (HIC) is also a major issue of linepipes exposed to a sour environment, the severity diagram does not necessarily correspond to the HIC susceptibility. Recently, from the viewpoint of fitness-of-purpose, the severity diagrams for HIC have been proposed based on the concept of equal hydrogen concentration. From this concept, HIC susceptibility corresponds well to the steady-state hydrogen permeability obtained from the hydrogen permeation test method. In this study, in order to clarify the relationship between HIC susceptibility and hydrogen diffusion behavior, in situ crack inspection during the HIC test and finite element method analysis of hydrogen diffusion were performed. The in situ inspection technique using phased-array ultrasonic testing which can capture the time dependence of crack distribution, and HIC initiation and propagation behaviors were clearly visualized and investigated. It was found that crack initiation and propagation stabilize as hydrogen concentration reaches a steady-state value throughout the specimen and the result was considered evidence that the HIC susceptibility corresponded with the steady value of hydrogen permeability.

Mesoeffect of the Dual Mechanism of Hydrogen-Induced Cracking

Mesoeffect of the Dual Mechanism of Hydrogen-Induced Cracking

Hydrogen-Induced Cracking of Welded Truss Gusset Plates

Hydrogen-Induced Cracking of Welded Truss Gusset Plates

Study on hydrogen-induced stress corrosion of 7N01-T4 aluminum alloy for railway vehicles

Abstract 7N01-T4 aluminum alloy is widely applied to high speed train body material attributed to its excellent comprehensive mechanical properties; however, its high sensitivity to hydrogen stress corrosion would seriously restrict its further application. In this study, the hydrogen-induced stress corrosion of the base metal and the joint was investigated under slow strain rate test to ascertain the characteristics and mechanism of hydrogen-induced stress corrosion cracking of aluminum alloy. By applying the cathode potential, the morphology of tensile port was studied. Results show that under the action of tensile stress, the free atomic hydrogen produced in the corrosion process or absorbed hydrogen diffuses along the grain boundary into the crack tip region, weakens the grain boundary and causes hydrogen embrittlement, thus accelerating the crack propagation and fracture. These properties provide a broader prospect for the application of 7N01-T4 aluminum alloy in high-speed train body.

Insight into efficient inhibitory of La3+ adsorbate on hydrogen permeation into steel

Addition of trace lanthanum salt in acid solution was found to be enhanced inhibitory effect on hydrogen permeation to X70 pipeline steel. The hydrogen permeation curves were performed to show that the addition of La 3+ inhibits hydrogen permeation by accelerating the recombination of the adsorbed hydrogen atoms and the desorption of hydrogen molecule, which decrease the subsurface hydrogen concentration. The inhibitory effect of La 3+ involves the film formation process. Moreover, electrochemical impedance spectroscopy analysis (EIS) depict that the inhibitive effect is caused by the catalysis of the recombination-desorption-evolution of adsorbed hydrogen atoms by La(OH) 3 /La 2 O 3 . This provides a novel solution for the prevention of hydrogen-induced cracking of high-strength steel, which often causes catastrophic accidents.

Investigation of the hydrogen-induced cracking of E690 steel welded joint in simulated seawater

Hydrogen-induced cracking (HIC) behavior and mechanism of E690 welded joint in simulated seawater were studied via microstructure observations, electrochemical hydrogen charging, slow strain rate tension (SSRT) tests and hydrogen content measurement. The results show that the welded joint of E690 steel has a higher HIC susceptibility than that of base metal, in which the inter-critical heat affected zone (ICHAZ) is composed of polygonal ferrite and granular bainite is the final fracture location in the joint. ICHAZ with the lowest yield strength deformed preferentially under the tensile stress, and subsequently, the proliferating dislocations with the deformation strengthening and the continuously charged hydrogen led to the HIC and brittle fracture at the ICHAZ of the welded joint. Moreover, the HIC susceptibility was linearly dependent on the logarithm of total hydrogen concentration in the steel, and the hydrogen concentration had a more obvious effect on the welded joint than the base metal. The higher density of piled dislocations adjoining the M/A islands in the welded joint exhibited a significant effect on the hydrogen agglomeration and diffusion, which enhanced the HIC susceptibility.

Key role of plastic strain gradient in hydrogen transport in polycrystalline materials

Hydrogen transport by moving dislocations is one of the key mechanisms for hydrogen embrittlement, which is considered responsible for local hydrogen accumulation at preferential crack initiation sites. Although numerous experiments corroborate this mechanism, there are few theoretical models for it available. In the present work, a novel hydrogen transport model is developed within the coupled framework of crystal plasticity and hydrogen balance. The hydrogen transport flux in the present model is divided into two parts: the first-order hydrogen transport flux driven by plastic strain and the second-order hydrogen transport flux driven by plastic strain gradient. With the calibrated parameters by fitting experimental results, the first-order hydrogen transport flux is negligible even for nickel with a low hydrogen diffusivity. In polycrystals, due to the intrinsic plastic heterogeneity induced by grain orientation mismatch, the second-order hydrogen transport flux results in significant dynamic hydrogen segregation at grain boundaries during deformation, which is expected to drive the hydrogen-induced intergranular cracking as observed in experiments. This dynamic segregation behavior is related to the evolution rate of geometrically necessary dislocations, depending on the grain boundary characters. The roles of grain refinement in hydrogen transport are clarified with the present model. This study shows the vital role of plastic strain gradient induced by grain boundary constraint in hydrogen transport, which is essential in understanding hydrogen migration and accumulation in deformed polycrystalline metals.

Sour corrosion performance and sensitivity to hydrogen induced cracking in the X70 pipeline steel: Effect of microstructural variation and pearlite percentage

In this study, the effect of the amount of pearlite and microstructural evolution on sour corrosion performance as well as sensitivity to hydrogen induced cracking (HIC) of an X70 steel was assessed. Heat treatment was performed at 875, 950, 1025 and 1100 °C on an API X70 steel that contained various amounts of pearlite (4.61%, 8.94%, 14.46%, and 17.18%). Optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and ImageJ software were employed to assess the effect of pearlite percentage and microstructural development on the mentioned properties. For the sour corrosion performance, open circuit potential (OCP), potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) in the H2S containing environment were employed. Also, HIC sensitivity of the X70 steel was measured using hydrogen charging of the cathode followed by tensile testing. Eventually, the damage caused due to the sensitivity to HIC was assessed using FE-SEM technique. Microstructural observations and phase analysis showed that a combination of ferrite, pearlite and (Ti, Nb) carbonitrides were developed in this steel, in which ferrite was considered as the main phase. Increasing the heat treatment temperature increased ferrite grain size as well as its stability, and reduced the amount of pearlite in the structure. Sour corrosion results showed that no active layer was formed on the surface of this pipeline steel. These latest results also showed that increasing the amount of pearlite reduced resistance against corrosion and increased sensitivity to corrosion of microgalvanic localization. As well, increasing the pearlite percentage and reduction of ferrite considerably raised the sensitivity to HIC of the API X70 steel. Finally, the increased sensitivity to HIC was observed in the form of surface initiated cracks in the charged samples.

Benzothiazolylhydrazine azomethine derivatives for efficient corrosion inhibition of mild steel in acidic environment: Integrated experimental and density functional theory cum molecular dynamics simulation approach

Synthesis of challenging corrosion inhibitors is of prime importance to inhibit hydrogen-induced and localised metallic corrosion occur in the corrosive acidic solution. In this regard, the present research has been focused on the development of functionalised Schiff bases, namely, 1-(benzo[d]thiazol-2-yl)-2-((furan-2-yl)methylene)hydrazine (BTFMH), 1-(benzo[d]thiazol-2-yl)-2-((thiophen-2-yl)methylene)hydrazine (BTTMH), 1-(benzo[d]thiazol-2-yl)-2-((5-methylthiophen-2-yl)methylene)hydrazine (BTMMH) with an aim of effectively curtailing the issues associated to hydrogen-induced cracking and subsequent inhibition of metallic corrosion taking place in the corrosive acidic solution. The corrosion inhibiting performances of the synthesized inhibitors have been assessed for mild steel surfaces exposed in 1 M HCl medium using gravimetric measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Potentiodynamic polarization study revealed that the synthesized inhibitor molecules retarded the cathodic hydrogen evolution reaction at cathodic site and subsequently minimized the oxidation of metals at anode; thereby, these Schiff bases acted as the mixed type inhibitors. The EIS study revealed that the corrosion inhibition phenomenon is being controlled through charge transfer processes. All of these three synthesized inhibitor molecules showed approximately 96–98 % corrosion inhibiting efficiency at exceedingly low concentration (0.5 mM). The inhibition efficacy obtained for these synthesized inhibitor molecules follows the order: BTMMH > BTTMH > BTFMH. The adsorption nature of these inhibitor molecules on mild steel surfaces have been revealed through surface morphology, topography and water contact angle studies. Thereafter, the insight of corrosion inhibition mechanism at atomic level have been explored by density functional theory (DFT). The optimized geometrical structure, electron density distribution of frontier molecular orbitals and their corresponding energy parameters obtained from DFT as well as Fukui indices analysis have been explored to unveil the plausible modes of adsorption or the reactive sites present within the inhibitor molecules which facilitate their interactions with surface atoms of metals. The non-covalent interaction based on reduced density gradient have been explored to study intrinsic feeble interaction acting with the molecules. Afterwards, molecular dynamics simulation has been employed to validate the spontaneity along with the nature of interaction at the metal inhibitor interface. Furthermore, the equilibrium adsorption configuration of the synthesized inhibitor molecules on the targeted metal surface atoms have been envisaged and the interfacial phenomenon has been explained.

Role of vanadium content in hydrogen diffusion behavior in X80 pipeline steel

ABSTRACT The role of vanadium content in hydrogen diffusion behaviour in X80 pipeline steel has been investigated. The results show that the hydrogen diffusion coefficient decreases from 1.54 × 10−6 cm2 s−1 in 1# steel with 0.03 wt-% vanadium to 9.97 × 10−7 cm2 s−1 in 3# steel with 0.14 wt-% vanadium due to the increase in irreversible and reversible traps. With the increase in vanadium content, more vanadium carbides precipitate in tested steels. The length (or number) of the low angle grain boundaries and special grain boundaries increase because of grain refinement, making the number of reversible traps increase. The dynamic condition of diffusible hydrogen in 3# tested steel with the largest number of hydrogen traps is the weakest. To weaken hydrogen-induced cracking dynamic condition, it is recommended to add 0.14 wt-% vanadium to X80 pipeline steel.

The influence of phosphorus on the temper embrittlement and hydrogen embrittlement of some dual-phase steels

The temper embrittlement (TE) and hydrogen embrittlement (HE) of some dual-phase (DP) steels were investigated, focusing on the influence of the phosphorus (P) content. An increased P content of 0.02 wt% caused little TE and enhancement of HE susceptibility in DP steels. Hydrogen had little influence on strength, but caused a significant decrease in ductility. For the DP steels with the different microstructures, the hydrogen-induced cracks initiated at the specimen surface, and hydrogen-induced micro-crack initiation was mainly martensite related. The increased martensite related cracking and the tendency of interface cracking was attributed by the enhanced element segregation (by both increased tendency of P segregation and promoted by other element segregation like Mn). The increased P content can enhance HE susceptibility through both interface weakening related HE mechanisms (HESIV, HEDE, or defactant) and ferrite ductility loss related HELP mechanism.

Investigation for enhancing the resistance of H-induced delayed cracking for martensitic steel by quenching tempering and quenching partitioning: Influence of microstructure on hydrogen embrittlement and cracking behavior

The objective of the present study is to enhance the hydrogen embrittlement (HE) of the commercial martensitic steel (QT220). For this purpose, the heat treatments of quenching tempering and quenching partitioning are conducted, labeled as QT400 and Q&QP400, respectively. Compared to QT220, the mechanical properties of the both heat-treated specimens are reduced, nevertheless, the HE resistance is extremely promoted, resulting from the lesser dislocations, the more MoyCx, and the existence of the strained interface of cementite. Besides the above favorable factors, the presence of the ferrite is another important factor which contributes to the lowest HE susceptibility in Q&QP400, resulting from the propagation's inhibition of hydrogen induced cracks (HICs) by ferrite. The HICs behavior of QT220, QT400 and Q&QP400 are mainly influenced by the dislocation glide, the cementite at the high angle boundaries and ferrite, respectively, mainly resulting in the fractographs of quasi-cleavage, intergranular and finely fragmented quasi-cleavage, respectively. In addition, HICs always deflect when propagating to the RD//<112∼114> orientations, providing a valuable direction for research to enhance the HE resistance in the future.

A Review on Cold Cracking Phenomenon in High Strength Steel Welded Joints (Causes and Cures)

Welding engineering becomes essentially important in all fabricating branches, such as; oil pipelines, ship industry, oil platforms, vehicle industry, oil tanks, and more applications. Hydrogen-induced cracking related to welding could be a source of genuine harm to welded structures. In this manner, it may be a common topic in such areas and its avoidance is an imperative issue. Steel weldability, with respect to cold cracking, is relative to steel hardenability, which indicates the forming of hard and fragile martensitic microstructure. The most perfect way to dodge martensite is by abating the cooling rate of the parent metal and warming the heat-affected zone. There are numerous arrangements to avoid the over issue, two of them are: preheating and the utilization of fewer hydrogen consumables. The current paper surveys a few of past and later inquiries that are coordinated towards getting a more coherent understanding of the impact of welding parameters on cold breaking shirking, centering especially on the impact of preheating technique and diffusible hydrogen levels on cold cracks of different steel types. However, one of the foremost vital discoveries of this ponder is that resistance to hydrogen-induced cracks has for the most part progressed in numerous steel types, and the required ways to dodge cold cracks by control of the welding conditions are well set up.

Comparative Analysis of Ultrasonic NDT Techniques for the Detection and Characterisation of Hydrogen-Induced Cracking.

The article is devoted to the investigation of ultrasonic inspection techniques suitable for detecting hydrogen-induced cracking (HIC) and a high-temperature hydrogen attack (HTHA), which are of great importance in petrochemical and refinery industries. Four techniques were investigated: total focusing method (TFM), advanced velocity ratio (AVR) measurement, advanced ultrasonic backscatter technique (AUBT) and time of flight diffraction method using ultra low angle ultrasonic transducers (TULA). The experimental investigation has been carried out on two carbon steel samples cut off from a heat exchanger of an oil refinery and potentially affected by HIC. It was shown that the AVR technique did not reveal any damage and was not effective in the case of the investigated samples due to a thin damage zone with respect to the total thickness of the samples. The AUBT method enabled us to indicate and classify the presence of the hydrogen-induced damage; however, it is complicated to use in practise due to the need perform measurements exactly at the same position using two transducers of different frequencies. The method is more suitable for the verification of damage at a particular position, rather than for scanning. Both other methods—TFM and TULA—enabled us to identify the presence of HIC in large areas of samples. The obtained results have been verified using a metallographic analysis of the section cut from the side of the sample. The results of metallographic examinations have been compared with indications observed using above mentioned techniques and a good correspondence was obtained. It was demonstrated, that the TFM method can detect cracks with dimensions close to 200 µm, while larger cracks of 2 mm were observed very evidently using a 7.5 MHz phased array. Overall, the results suggested that the TULA method is the most suitable method for the primary detection of hydrogen-induced cracking, while the TFM is recommended for the precise assessment of the extent of the detected cracking.

Suppressed hydrogen embrittlement of high-strength Al alloys by Mn-rich intermetallic compound particles

The pursuit of strong and ductile Al alloys with superior resistance to hydrogen embrittlement (HE) is practically significant across the aerospace and transportation industries among others. Unfortunately, effective ways to progress on the strength-HE trade-off for Al-alloys remain elusive. A strategy of suppressing HE by introducing intermetallic compound (IMC) particles to achieve hydrogen redistribution in various trapping sites was proposed. Here, we systematically induce the precipitation of a constant volume fraction of intermetallic compound (IMC) particles by adding one of 14 elements in a ternary Al-Zn-Mg high-strength alloy. We show a strong correlation between hydrogen trapping energies of the IMC obtained from ab initio calculations with the resistance to HE. Mn-rich Al11Mn3Zn2 particles exhibit the highest hydrogen trapping energy (0.859 eV/atom), leading to a decrease by approximately 5 orders of magnitude in the hydrogen occupancy in η2 (MgZn2) phase interfaces and grain boundaries, where HE cracks initiate. The Mn-addition did not deteriorate the ductility and most Al11Mn3Zn2 particles remained intact during plastic deformation which was revealed by in-situ 3D X-ray tomography. Hydrogen-induced strain localization at η2 phase interfaces and grain boundaries were inhibited due to strong hydrogen trapping capacity of Al11Mn3Zn2, hence preventing HE cracks initiation. Our approach effectively suppresses hydrogen-induced cracks without sacrificing the ductility, and our strategy can help the design roadmap of HE-tolerant high-strength metallic alloys.

Preferential Locations of Hydrogen Accumulation and Damage in 1.2 GPa and 1.8 GPa Grade Hot-Stamped Steels: A Comparative Study

In this work, hydrogen segregation and damage sites in 1.2 GPa and 1.8 GPa grade hot-stamped steels were comparatively investigated by hydrogen permeation experiments and the hydrogen microprint technique (HMT). Compared with 1.2 GPa steel, 1.8 GPa steel exhibited a lower hydrogen diffusion coefficient (Deff) and a higher number of hydrogen trapping sites (Nt) due to its finer microstructure and richer nano-sized precipitates. The results of HMT showed that the grain boundaries in both steels played a role in initial hydrogen segregation, and then the martensitic laths became the locations of hydrogen accumulation. For 1.2 GPa and 1.8 GPa steels, however, hydrogen accumulation appeared preferentially on martensitic laths and grain boundaries, respectively, resulting in various damage behaviors. The introduced nano-sized carbides as “good hydrogen traps” played an important role in hydrogen diffusion, accumulation, and damage, which greatly alleviated hydrogen-induced cracking for the 1.8 GPa steel. Moreover, electron backscatter diffraction (EBSD) analysis further revealed that the damage behavior was also controlled by the low-angle grain boundary, stress distribution, and recrystallization fraction of the samples.

Effects of inclusions on the fatigue life of SNCM439 steel in high-pressure hydrogen gas

Four heats of commercially available JIS SNCM439 steel are prepared, and fatigue tests are conducted in air and hydrogen gas. The materials evaluated are all martensitic steel with a tensile strength of 900 MPa or less and contain nonmetallic inclusions of different sizes. A decrease in the fatigue limit is observed in the specimens with large nonmetallic inclusions, but the fatigue limit in air is approximately equal to the fatigue strength at 300,000 cycles in hydrogen. However, in the finite life region, the fatigue life in hydrogen significantly decreases owing to the presence of large nonmetallic inclusions. It was observed that hydrogen considerably affects the fatigue life even at low stress amplitudes close to the fatigue limit. This effect is considered to be dependent on the size of the initial crack originating from the nonmetallic inclusions; large nonmetallic inclusions accelerate the hydrogen-induced fatigue crack growth rate.