In this investigation, the effect of microstructural changes and phase equilibria on corrosion behavior and hydrogen induced cracking (HIC) sensitivity of an API X65 pipeline steel was studied. For this purpose, heat treatment was performed at 850 °C, 950 °C, 1050 °C and 1150 °C to engineer the desired microstructure of this pipeline steel. Then, the microstructural evolution was performed by optical microscopy, and Field Emission Scanning Electron Microscopy (FE-SEM) equipped with Energy Dispersive X-Ray Spectroscopy (EDS). Corrosion properties were evaluated in H2S environment by open circuit potential (OCP), Potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS). As well, HIC sensitivity of the API X65 pipeline steel was assessed by hydrogen charging of the cathode and immediately conducting the tensile test. Microscopy analyses showed that the microstructure of the steel is ferritic-pearlitic together with the islands of martensite/austenite constituents. Increasing the heat treatment temperature reduced the amount of pearlite and increased ferrite grain size. It also stabilized the ferrite content. Corrosion results indicated that no active layer was formed on the surface of this pipeline steel. Also, increasing the heat treatment temperature increased the corrosion resistance and reduced sensitivity to micro-galvanic localized corrosion. As well, results suggested that the sensitivity to HIC in the API X65 pipeline was substantially increased with increasing the amount of pearlite and reducing the amount of ferrite; i.e. at lower heat treatment temperature.

Sensitivity to hydrogen induced cracking, and corrosion performance of an API X65 pipeline steel in H2S containing environment: influence of heat treatment and its subsequent microstructural changes

• Hydrogen embrittlement (HE) of multi-principal element alloys is reviewed. • HE behavior between traditional alloys and high-entropy alloys is compared. • Further research directions on HE of high-entropy alloys are identified. • Strategy for the improvement of strength and HE-resistance are suggested. Multi-principal element alloys exhibit excellent physical, chemical and mechanical properties, and they are used as novel structural materials for potential applications in nuclear energy, hydrogen energy, and petrochemical fields. However, exposing components made of the alloys to service conditions related to the mentioned applications may induce hydrogen embrittlement (HE) as one of the typical failure mechanisms. In this review, we report and summarize the progress in understanding HE in multi-principal element alloys, with a particular focus on high-entropy alloys (HEAs). The review focuses on four aspects: (1) hydrogen migration behavior (hydrogen dissolution, hydrogen diffusion, and hydrogen traps); (2) factors affecting HE (hydrogen concentration, alloy elements and microstructure); (3) tensile mechanical properties in the presence of hydrogen and micro-damage HE mechanisms; (4) the design concept for preventing hydrogen-induced mechanical degradation. The differences in the HE behavior and failure mechanisms between HEAs and traditional alloys are compared and discussed. Moreover, specific research directions for further investigation of fundamental HE issues and a strategy for a simultaneous improvement in strength and HE resistance are identified. 

Hydrogen embrittlement and failure mechanisms of multi-principal element alloys: A review

http://manuscript.elsevier.com/S1875510022001378/pdf/S1875510022001378.pdf

Hydrogen-induced cracking and blistering in steels: A review

Biotic enhancement of Desulfovibrio desulfuricans on multi-factor influenced corrosion of X80 steel in saline soil

Influence of electrochemical hydrogenation parameters on microstructures prone to hydrogen-induced cracking

Effect of hydrogen charging time on hydrogen blister and hydrogen-induced cracking of pure iron

The effect of surface roughness on hydrogen-induced blister behavior in pure iron was explored using optical microscopy and microcomputerized tomography. Hydrogen was introduced into the samples by electrochemical precharging methods with various hydrogen charging times. It is found that grinded surface exhibits higher roughness and compressive residual stress compared to those of polished surface. With increasing hydrogen charging time, hydrogen-induced blister height, blister width and blister area fraction increase, regardless of the grinded surface and polished surface. Further, hydrogen blister height and width of grinded surface are comparative to polished surface under the same hydrogen charging time. However, the blister area fraction and the number of blister on polished surface are considerably higher than the grinded surface, indicating that polished surface is more susceptible to the formation of blisters than that of grinded surface, both of surface and interior of the samples. This is dominantly rationalized in terms of the suppression effect of hydrogen invasion in grinded surfaces due to their higher residual compressive stress and higher dislocation density.

Xubin Wu

Papers

Effect of hydrogen charging time on hydrogen blister and hydrogen-induced cracking of pure iron

Effect of Surface Roughness on Hydrogen-Induced Blister Behavior in Pure Iron