Effect of Surface Roughness on Hydrogen-Induced Blister Behavior in 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.

The Hydrogen Blistering Formed on the Surface of A333Gr6 Pipeline Steel Exposed to Wet H2S Solution

After Hydrogen-induced cracking (HIC) test, many hydrogen blisters appeared on the surface of A333Gr6 pipeline steel. The amount of hydrogen blistering depends on the sample location. The amount and area rate of the hydrogen blistering on the surface of A333Gr6 sample near the internal wall are more than those of the sample near the external wall. After the upper part of the hydrogen blisters were torn off, the fracture surfaces of the upper and lower parts of the blister were analyzed by scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS). The cell segregation inclusion of alloying elements which contain Ca and Al sulfides and oxides were observed in most of the nucleation sites of hydrogen blisters. The result shows that the dislocations and the increasing vacancy concentration are the main reasons to form hydrogen cavities in the nucleation sites. The hydrogen pressure which exceeds the strength of the materials will cause the formation of hydrogen blister.

Use of Phased Array Ultrasonic Testing For Sizing of Hydrogen Blisters In LPG Wash Water Vessel In INDMAX Unit

Equipments operating in sour environment containing H2S are prone to deterioration by wet H2S damage mechanism. INDMAX unit (patented FCCU) produces LPG which contains H2S, cyanide as impurities. To remove these impurities LPG is treated with caustic wash and subsequently water wash in series operation. Due to presence of wet H2S environment in the water wash vessel, nascent hydrogen is produced which diffuses in to the wall of the vessel. Due to presence of laminations in the CS shell these hydrogen atoms combined to form hydrogen molecule which exerts severe internal pressure greater than the yield strength of the CS wall inside the laminations resulting in formation of hydrogen blister. This paper describes the use of phased array UT (PAUT) technique for detection of lamination and sizing of hydrogen blisters in the LPG wash water vessel. Fitness for purpose study was carried out for safe operation of this vessel.

Activation Energy and Blistering Rate in Hydrogen-implanted Semiconductors

ABSTRACTHydrogen blister rates in Si (100), Si (111) and Ge (100) substrates are compared as a function of annealing temperature and time, for a range of implant energies and fluences. For each material, the rate of blister formation was found to exhibit Arrhenius behavior and to be characterised by a single activation energy over the temperature range examined. The extracted activation energies were 2.28±0.03 eV, 2.17±0.06 eV and 1.4±0.03 eV for (100) Si; (111) Si and (100) Ge, respectively. These results are compared with reported measurements and discussed in relation to proposed models of hydrogen blistering.

Failure Analysis of Hydrogen Corrosion of the Lens Gasket

The 10MoWVNb steel lens gaskets are widely used for the flange linking of high pressure tube in the synthetic ammonia system in chemical fertilizer plant. The gasket worked in H2-N2-NH3 environment at the temperature of 300°C. It often fails because of hydrogen corrosion. The microstructure and corrosion characteristic of the lens gasket were studied by optical microscope. The results showed that the hydrogen blister appeared preferentially at the interface of inclusions. The corrosion depth was 0.65 millimeter. There were little intergranular crack on inner surface.