Hydrogen Induced Cracking Resistance Research Articles

Improving HIC resistance of pipe-steel by Ti/Mg treatment with insights into hydrogen migration

The presence of inclusions in steels is responsible for hydrogen-induced cracking (HIC), which necessitates control over their size and distribution. The aims of this study are to investigate the effects of different inclusion-modifying elements on steels, as well as reveal the impact of inclusions on hydrogen migration. Various methods, including HIC evaluation, electrochemical hydrogen permeation, silver microprint, and in-situ hydrogen escape observation, are utilized. The results indicate that steel with a Ti/Mg content ratio of 4:1 exhibits favorable comprehensive resistance against HIC. Moreover, the observation of in-situ hydrogen escape observations reveals that steels with a higher number of hydrogen bubbles and a higher ratio of bubbles related to the inclusions demonstrate better HIC resistance. The refined, dispersed, and multi-compounded inclusions facilitate the formation of more complex trapping sites, ultimately improving the dispersion and pinning of dissociative hydrogen atoms. Consequently, employing a multicomponent inclusion modification strategy holds promise for the development of hydrogen-resistant pipeline steel.

Synergistic addition of Cu and Ce enhanced sulfate reducing bacteria-assisted corrosion cracking resistance of 2205 duplex stainless steel

The corrosion behaviors of 2205, 2205-Cu, and 2205-Cu-Ce duplex stainless steels (DSSs) were studied under static load in the presence of sulfate-reducing bacteria (SRB). The results demonstrated that the addition of Cu and Ce effectively enhanced the resistance of 2205 DSS to SRB-assisted cracking, and 2205-Cu-Ce DSS exhibited the best corrosion resistance and mechanical properties. The Synergistic addition of Cu and Ce not only inhibited the formation of SRB biofilm but also enhanced the hydrogen-induced cracking resistance of DSSs due to the hydrogen trapping by Cu-rich precipitates.

Research on hydrogen induced cracking (HIC) performance of vessel steels

Hydrogen-induced cracking performance is quite important for vessel steels. But for this type of medium carbon steel, studies on the effect of the dislocation density and distribution condition of carbides on hydrogen-induced cracking performance were insufficient. In this study, the tested steel was treated with three different heat-treatment processes: scanning electron microscopy (SEM), hydrogen-induced cracking tests (HIC), and transmission electron microscope (TEM), which were used to reveal the mechanism of affecting hydrogen-induced cracking performance. The results showed that microstructure, dislocation density, and distribution condition of carbides were the significant key to the hydrogen-induced cracking performance of tested steels. As the tempering temperature grew from 450°C to 650°C, the density of dislocation gradually went down from 9.71/1010 cm-1 to 2.97/1010 cm-1. And the shape of carbides transformed from bar into fine particles, and the area fraction increased from 37% to 44%. More uniformly distributed carbides can enhance hydrogen-induced cracking resistance because it can promote trapped hydrogen atoms uniformly distribute, reduce the local hydrogen pressure and prohibit crack initiation and propagation. In other words, a tempering temperature above 550°C would be beneficial for the hydrogen-induced cracking performance of vessel steels.

The effect of non-metallic inclusion morphology on the hydrogen induced cracking (HIC) resistance of L80 steel

The hydrogen induced cracking (HIC) resistance of four (4) L80 casing steels, with different nominal compositions and processing conditions, was determined using the NACE TM0284 HIC test. Microstructural and inclusion characterization of each steel was undertaken using optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The morphology (equivalent diameter, aspect ratio and major length) of inclusions over identical analysis regions were measured for each steel. In total, >15,000 inclusions were characterized. Non-linear models correlating inclusion morphology with the measured values of CLR (crack length ratio) and CTR (crack thickness ratio) were developed. The models show that both CLR and CTR are complex functions of the diameter (equivalent) of oxide-based inclusions and the major length of the manganese sulfide (MnS) stringers. The models show that oxides <10 μm in diameter were found to have negligible effect on HIC resistance (CLR) while oxides >20 μm exhibited a significant and escalating negative impact on HIC resistance comparable to long (>50 μm) MnS stringers.

Effect of Oxide Metallurgy Technology on Mechanical Properties and Hydrogen‐Induced Cracking Susceptibility of High‐Strength Low‐Alloy Steel

The oxide metallurgy is used in the fabrication of X80 pipeline steel. The mechanical properties of X80 steel at different tempering temperatures are studied by offline heat treatment process. The hydrogen‐induced cracking (HIC) susceptibility of X80 steel with optimal mechanical properties is studied. The results show that the optimal combinations of mechanical properties are obtained for the X80 pipeline steel under the heat treatment conditions of water quenched at 900 °C and tempered at 630 °C. The yield strength of the X80 steel is 569 MPa and the impact energy is higher than 300 J at −40 °C. After deoxidation by Ti and Zr, the average size of inclusions in X80 steel is 0.23 μm. Among them, the typical spherical composite inclusions are TiOX–Al2O3–ZrO2–MnS, combined with the fine (Nb, V, Ti)C and the formation of Cu2S and Cr2O3 protective layers. X80 steel has excellent HIC resistance.

Improving hydrogen induced cracking resistance of high strength acid-resistant submarine pipeline steels via trace-Mg treatment

Hydrogen induced cracking (HIC) is one of the biggest service risks faced by high-strength acid-resistant submarine pipeline steel. In this work, we reported a low-carbon, low-cost and high-efficient method for remarkably improving HIC resistance of the high-strength acid-resistant submarine pipeline steels by trace-Mg treatment. The results showed that the non-metallic inclusions steels were obviously refined, softened, spheroidized and dispersed by trace-Mg treatment, the modified “core-shell” or like “core-shell” structure inclusions had a larger critical size for HIC initiation and a higher saturated hydrogen concentration, and then effectively trapping more hydrogen, dispersing hydrogen pressure and reducing the diffused hydrogen content, thus effectively improving the HIC resistance. With the further increasing of Mg contents, the inclusion modification would be weakened, the hydrogen trapping efficiency decreased, and the HIC susceptibility of the tested steel increased again. In the research range, the tested steels treated with 4 ppm Mg present the lowest HIC susceptibility.

Review of Current Developments on High Strength Pipeline Steels for HIC Inducing Service

Nowadays, an increasing number of oil and gas transmission pipes are constructed with high-strength low alloy steels (HSLA); however, many of these pipelines suffer from different types of hydrogen damages, such as hydrogen-induced cracking (HIC). So many research efforts are being carried out to reduce the detrimental effects of hydrogen damage in HSLA steel pipes. The thermomechanical control process (TMCP) is a microstructural control technique that is able to eliminate the conventional heat treatment after hot rolling. Recent research demonstrated that TMCP provides high HIC resistance without adding high amounts of alloying elements or expensive heat treatments. However, once these HSLA steel pipes are put into service, they experience HIC damage, and the prediction of its kinetics is a necessary condition to perform Fitness-For-Service assessments. To develop a reliable predictive model for the kinetics of HIC, the relations among the microstructural features, environmental parameters, and mechanical properties have to be fully understood. This paper presents a review of the key metallurgical and processing factors to develop HSLA steel pipes, as well as a review of the phenomenological and empirical models of HIC kinetics in order to identify specific research directions for further investigations aimed to establish a reliable and sound model of HIC kinetics.

Process Stability and Application of 1900 MPa Grade Press Hardening Steel with reduced Hydrogen Susceptibility

While 22MnB5 with aluminium silicon (AS) coating was established as the quasi-standard in press hardening many years ago, the need for steels that offer even higher strength is growing. These needs include corrosion protection of the automotive component and scale prevention during processing in hot forming lines. However, the processing of AS coated ultra-high strength steels involves demands for the furnace atmosphere. Reducing the hydrogen susceptibility and increasing the material strength at the same time was the driving force for the development of MBW 1900 + AS Pro. The paper focuses on the process stability of this steel concerning furnace and stamping parameters as well as the hydrogen induced cracking resistance under different dew points in the furnace atmosphere. In addition, the potential by means of different partial press hardening processes is presented. With tailored tempering, locally heated tools can be used to achieve soft areas in the part. Furthermore, the application potential of MBW 1900 + AS Pro in tailor welded blanks is shown.

Effects of different cooling rates on the microstructure, crystallographic features, and hydrogen induced cracking of API X80 pipeline steel

Hydrogen-Induced Cracking (HIC) is a primary failure mechanism of pipeline-welded joints in the absence of external loading in the oil and gas exploration industries. Three different cooling rates after austenitization were used to simulate in the laboratory different regions of the heat-affected zone (HAZ) formed when welding an API X80 pipeline steel specially designed to enhance the HIC resistance. The samples were characterized with regard to microstructure and crystallography as well as HIC resistance. The HIC resistance test used NACE TM0284-2011 methodology. The microstructure and its homogeneity varied as a function of cooling rates. Samples containing inclusions and segregation zone from the segregation bands of specimens showed reduced HIC resistance, while specimens containing only acicular ferrite and granular bainite coupled with the absence of segregation zone showed significant improvement in HIC resistance. The best HIC resistance results came from samples presenting fine acicular ferrite consisting of fine interlocking plates, with divergent crystallographic orientations, preventing the formation of localized strain distribution inside the grain and at grain boundaries. It was also found that a large proportion of medium-angle boundaries prevent microcrack initiation and the transgranular mode of crack propagation.

Effect of nanosized NbC precipitates on hydrogen-induced cracking of high-strength low-alloy steel

We investigated the effect of nanosized NbC precipitates on hydrogen-induced cracking (HIC) of high-strength low-alloy steel by conducting slow-strain-rate tensile tests (SSRT) and performing continuous hydrogen charging and fracture analysis. The results reveal that the HIC resistance of Nb-bearing steel is obviously superior to that of Nb-free steel, with the fractured Nb-bearing steel in the SSRT exhibiting a smaller ratio of elongation reduction (Iδ). However, as the hydrogen traps induced by NbC precipitates approach hydrogen saturation, the effect of the precipitates on the HIC resistance attenuate. We speculate that the highly dispersed nanosized NbC precipitates act as irreversible hydrogen traps that hinder the accumulation of hydrogen at potential crack nucleation sites. In addition, much like Nb-free steel, the Nb-bearing steel exhibits both H-solution strengthening and the resistance to HIC.

Comprehensive study on hydrogen induced cracking of electrical resistance welded API X52 pipeline steel

Different heat treatment cycles were designed in order to investigate the effect of microstructural changes on hydrogen induced cracking resistance (HIC) and mechanical properties of the electric resistance welded steel. The heat treating of the as-welded specimen improved the ductility and impact toughness. After heat treatment, the uniform hardness profile was obtained for the welded specimens. The removal of local hard zones reduced the risk of HIC. The chemical composition and clustering of inclusions have a deleterious effect on cracking resistance in the H2S environment. Aluminosilicate compounds and MnS inclusions were favorite sites for HIC. The most promising post weld heat treatment for improving mechanical properties and the resistance to HIC was the application of two-cycle quenching followed by tempering.

Effects of thermal spray aluminium coating on SSC and HIC resistance of high strength steel in a sour environment

Flexible risers are critical equipment for the production of oil and gas in offshore fields around the world. The annulus region may condense acidic water containing H2S exposing the tensile armour steel wires to a sour environment, which may promote sulphide stress cracking (SSC) and/or hydrogen-induced cracking (HIC). This work aims to evaluate through electrochemical and constant displacement tests the effectiveness of thermal spray aluminium (TSA) coating to mitigate SSC and HIC in high strength steel used to manufacture the tensile armour of a flexible riser. Electrochemical tests confirmed the anodic behaviour of the coating against the steel and estimated a service life of 2.5 years. The constant displacement test indicated that the non-coated samples failed by SSC although some cracks were also found in the samples mid-section due to HIC. For Al-coated samples, no signs of SSC and HIC were observed. The TSA coating showed a dual barrier effect, hindering either corrosion of steel or hydrogen up-taking, and neither SSC nor HIC was observed. Samples with a coating defect were cathodically protected and no HIC was observed.

Comparative study of non-metallic inclusions on the critical size for HIC initiation and its influence on hydrogen trapping

In the present work, the critical crack nucleation size and the hydrogen trapping capability of inclusion were discussed with a numerical simulation considering the factors of inclusion/matrix heterojunction. The results showed that the inclusion composition had a significant effect on hydrogen capacity and its critical nucleation size of hydrogen-induced cracking (HIC). The MnS inclusions exhibited a larger critical size tolerance of HIC nucleation (approximately 2.5 μm), but for some typical oxide inclusions, it ranged between 0.1 and 0.4 μm. In addition, two sheets of steel containing different composition, morphology, and distribution of inclusions were studied by the standard-based test and thermal desorption spectroscopy (TDS) to evaluate the HIC susceptibility and hydrogen trapping behaviour. The results complementarily demonstrated that when controlling the non-metallic inclusions into the proper size and compound with MnS into the sphere, the HIC resistance of steel could be efficiently improved.

A Comparative Investigation of the Corrosion Resistance and HIC Suceptibility of API 5L X65 and API 5L X80 Steels

High strength low alloy (HSLA) steels are used for the construction of pipelines for oil and natural gas transportation. For such applications pipelines must exhibit mechanical resistance and resistance to corrosion and hydrogen induced cracking (HIC). API 5L X65 steels are the main materials used for this purpose. However, for economic reasons, the use of steels of superior grades would be of interest. This work presents a comparative study of the corrosion and HIC resistances of an API 5L X65 and an API 5L X80 steel in deaerated solution A of NACE TM0284 standard. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization experiments were performed in non-sour and sour (H2S-saturated) media, and HIC resistance tests were carried out in the sour medium. Scanning electron microscopy (SEM) and optical microscopy (OM) characterizations of polished and corroded samples were also done. Electrochemical tests showed that the API 5L X80 steel is slightly more susceptible to surface corrosion, which can be probably linked to its higher inclusion content and smaller grain sizes, it was also susceptible to HIC. Mn and S-rich inclusions found in the crack path indicate that this microstructural feature may play a key role in crack propagation and HIC susceptibility

X-COR

Abstract This alloy is a special steel grade for pressure vessels with HIC (hydrogen-induced cracking) resistance. This datasheet provides information on composition. It also includes information on corrosion resistance as well as forming and joining. Filing Code: SA-825. Producer or source: ThyssenKrupp Steel Europe AG.

Hydrogen induced cracking susceptibility of API 5L X70 pipeline steel in relation to microstructure and crystallographic texture developed after different thermomechanical treatments

Thermomechanical treatments offer an innovative means of controlling microstructure development and improving resistance to hydrogen induced cracking (HIC) in pipeline steel. This study was conducted on two X70 pipeline steels (labelled WG and WH) of the same chemical composition, but processed with different thermomechanical parameters. Specimen WG was hot rolled at a higher temperature range of 880–820 °C, while specimen WH was hot rolled between 830 and 760 °C before cooling at a rate of 25 °C/s. Early onset of HIC was observed in specimen WH after electrochemical hydrogen charging for 12 h in a solution of 0.2 M H2SO4 and 3 g/l NH4SCN, without any applied stress. Also, test pieces from the surface and mid-thickness layers of each pipeline steel were subjected to slow strain rate tensile (SSRT) test with in-situ hydrogen charging. Characterization techniques such as Optical Microscopy, Scanning Electron Microscopy, Electron Backscattered Diffraction and X-ray Diffraction were used to investigate the structure pipeline steel specimens. The role of inclusions on HIC was studied by Energy Dispersive X-ray Spectroscopy. Although the microstructure of both specimens were predominantly ferritic, more martensite/retained austenite (M/A) constituents featured in WG. Further crystallographic texture analysis indicates that grain orientation at the surfaces of both test specimens were similar with deviations towards 〈111〉 on the inverse pole figure (IPF); whereas, pole intensity at the mid-thickness deviated towards the 〈001〉 direction. Considering the increased fraction of banded-deformed grains with high stored energy, the lower HIC resistance of specimen WH in comparison to specimen WG was justified.

Effects of vanadium precipitates on hydrogen trapping efficiency and hydrogen induced cracking resistance in X80 pipeline steel

In this study, the number and size distribution of vanadium precipitates and their effects on hydrogen trapping efficiency and hydrogen-induced cracking (HIC) susceptibility were investigated in X80 pipeline steel. The results showed that as the vanadium content increased, the number of nanoscale vanadium precipitates clearly increased. Furthermore, the amount of hydrogen atoms trapped by vanadium precipitates gradually increased and the hydrogen diffusion coefficient decreased from 4.74 × 10−6 cm2 s−1 in the vanadium-free V0 steel to 8.48 × 10−7 cm2 s−1 in the V4 steel with 0.16% V, according to hydrogen permeation results. It also reduced the possibility of hydrogen atoms diffusing into the sites of harmful defects such as large-size oxides and elongated MnS inclusions, where cracks were caused more easily. In addition, the V3 steel with 0.12% V, containing the largest number of vanadium carbide particles of less than 60 nm, had the lowest HIC susceptibility.

Hydrogen-Induced Cracking Resistance of Novel Cu-Bearing Pipeline Steels

Hydrogen-Induced Cracking Resistance of Novel Cu-Bearing Pipeline Steels

Strengthening mechanism and hydrogen-induced crack resistance of AISI 316L stainless steel subjected to laser peening at different power densities

Microstructural response of AISI 316L stainless steel to laser peening (LP) was examined by means of optical microscopy (OM) and transmission electron microscopy (TEM) in order to analyze the effects of LP on hydrogen-induced cracking (HIC) resistance. Depth profiles of near-surface microhardness and surface compressive residual stress (CRS) of LP treated specimens were presented respectively. Slow strain rate tensile tests were performed on the hydrogen-charged samples and their corresponding stress-strain curves as well as fracture morphologies were finally investigated in detail. The results demonstrated that LP induced a grain refinement effect on the treated surface while a maximum refining rate of 56.18% was achieved at the laser power density of 10 GW/cm2. The near-surface microhardness also exhibited an attenuation trend with the increasing depth. The surface CRS positively correlated with power density before it reached a threshold value. A special U-shaped dislocation tangle band was observed in the LP treated specimen which served as hydrogen trapping sites. The LP treated samples exhibited better toughness after hydrogen charging from both macro mechanical properties and micro fracture morphologies. LP-induced grain refinement and CRS are believed to be the main contributing factors towards inhibiting the diffusion of hydrogen atoms which ultimately leads to the reduction of the hydrogen embrittlement sensitivity of AISI 316L stainless steel.

Effect of Nb on the hydrogen-induced cracking of high-strength low-alloy steel

Hydrogen-induced cracking (HIC) susceptibility tests, hydrogen permeation tests and the electron backscatter diffraction (EBSD) measurements were used to study the effect of Nb on the HIC resistance of the high-strength low-alloy (HSLA) steel. The Nb microalloying significantly improved the HIC resistance and decreased the proportion of intergranular cracks through the hydrogen trapping effect and microstructure optimization. Dispersed nanometer-sized NbC precipitates effectively increased the number of irreversible traps, hindered hydrogen aggregation, and enhanced the resistance to crack initiation and propagation. Moreover, Nb optimized the microstructure by increasing the proportion of the low-angle grain boundaries (LAGBs), refining the prior austenite grain size, decreasing the dislocation density, and changing the distribution of Σ3 boundaries.