scholarly journals Hydrogen-Assisted Crack Growth in the Heat-Affected Zone of X80 Steels during in Situ Hydrogen Charging

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2575 ◽  
Author(s):  
Qu ◽  
Feng ◽  
An ◽  
Bi ◽  
Du ◽  
...  
Keyword(s):  
Hydrogen Embrittlement ◽  
Base Metal ◽  
Current Density ◽  
Heat Affected Zone ◽  
Tensile Tests ◽  
Electron Back Scatter Diffraction ◽  
Propagation Path ◽  
Hydrogen Charging ◽  
X80 Steels

Herein, the hydrogen embrittlement of a heat-affected zone (HAZ) was examined using slow strain rate tension in situ hydrogen charging. The influence of hydrogen on the crack path of the HAZ sample surfaces was determined using electron back scatter diffraction analysis. The hydrogen embrittlement susceptibility of the base metal and the HAZ samples increased with increasing current density. The HAZ samples have lower resistance to hydrogen embrittlement than the base metal samples in the same current density. Brittle circumferential cracks located at the HAZ sample surfaces were perpendicular to the loading direction, and the crack propagation path indicated that five or more cracks may join together to form a longer crack. The fracture morphologies were found to be a mixture of intergranular and transgranular fractures. Hydrogen blisters were observed on the HAZ sample surfaces after conducting tensile tests at a current density of 40 mA/cm2, leading to a fracture in the elastic deformation stage.

scholarly journals Hydrogen Embrittlement Behavior of 18Ni 300 Maraging Steel Produced by Selective Laser Melting

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2360 ◽  
Author(s):  
Young Jin Kwon ◽  
Riccardo Casati ◽  
Mauro Coduri ◽  
Maurizio Vedani ◽  
Chong Soo Lee
Keyword(s):  
Hydrogen Embrittlement ◽  
Maraging Steel ◽  
Selective Laser Melting ◽  
Solution Treatment ◽  
Tensile Tests ◽  
Constant Current ◽  
Hydrogen Atoms ◽  
Laser Melting ◽  
Constant Current Density ◽  
Hydrogen Charging

A study was performed to investigate the hydrogen embrittlement behavior of 18-Ni 300 maraging steel produced by selective laser melting and subjected to different heat treatment strategies. Hydrogen was pre-charged into the tensile samples by an electro-chemical method at the constant current density of 1 A m−2 and 50 A m−2 for 48 h at room temperature. Charged and uncharged specimens were subjected to tensile tests and the hydrogen concentration was eventually analysed using quadrupole mass spectroscopy. After tensile tests, uncharged maraging samples showed fracture surfaces with dimples. Conversely, in H-charged alloys, quasi-cleavage mode fractures occurred. A lower concentration of trapped hydrogen atoms and higher elongation at fracture were measured in the H-charged samples that were subjected to solution treatment prior to hydrogen charging, compared to the as-built counterparts. Isothermal aging treatment performed at 460 °C for 8 h before hydrogen charging increased the concentration of trapped hydrogen, giving rise to higher hydrogen embrittlement susceptibility.

FE Simulation of Cold Cracking Susceptibility in X70 Structural Steel Welded Joints

2011 ◽  
Author(s):  
Vigdis Olden ◽  
Odd Magne Akselsen
Keyword(s):  
Hydrogen Embrittlement ◽  
Yield Strength ◽  
Structural Steel ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Fe Simulation ◽  
Coarse Grained ◽  
Best Fitting ◽  
Low Sensitivity

Fracture mechanics SENT testing and FE simulation to establish hydrogen influenced cohesive parameters for X70 structural steel welded joints have been performed. Base metal and weld simulated coarse grained heat affected zone have been included in the study. The base metal did not fail at net section stresses lower than 1.29 times the yield strength and reveals low sensitivity to hydrogen embrittlement. The weld simulated coarse grained heat affected zone was prone to fracture at stresses above 64% of the yield strength, which indicates hydrogen embrittlement susceptibility. The cohesive parameters best fitting the experiments are δc = 0.3 mm and σc = 1700 MPa (3.5·σy) for the base metal and δc = 0.3 mm and σc = 2100 MPa (2.6·σy) for the coarse grained heat affected zone.

Hydrogen Embrittlement of PH 13-8 Mo Stainless Steel—The Effect of Surface Condition

CORROSION ◽  
1984 ◽  
Vol 40 (4) ◽  
pp. 146-151 ◽  
Author(s):  
G. T. Murray ◽  
H. H. Honegger ◽  
T. Mousel
Keyword(s):  
Stainless Steel ◽  
Hydrogen Embrittlement ◽  
Precipitation Hardening ◽  
Surface Condition ◽  
Tensile Tests ◽  
Time To Failure ◽  
Hydrogen Charging ◽  
Charging Time ◽  
Cold Worked ◽  
Effect Of Surface

Abstract The susceptibility of precipitation hardening 13-8 Mo stainless steel to hydrogen embrittlement (HE) was measured by both post hydrogen charging tensile tests and by time to failure tests while being subjected to hydrogen charging and a static stress below the yield stress. In the former, it was found that the ductility was decreased substantially after only 30 min charging time. The strength was markedly reduced after 2 h charging time. In the delayed failure tests, it was found that a localized cold worked surface condition promoted crack formation.

Evaluation of Welding Metal Zones in the Case Welded with 0.5 Mo Filler Metal to Forged Steel for Piston Crown Material

2014 ◽  
Vol 887-888 ◽  
pp. 1294-1300
Author(s):  
Kyung Man Moon ◽  
Jong Pil Won ◽  
Dong Hyun Park ◽  
Sung Yul Lee ◽  
Yun Hae Kim ◽  
...  
Keyword(s):  
Weld Metal ◽  
Combustion Chamber ◽  
Base Metal ◽  
Current Density ◽  
Heavy Oil ◽  
Heat Affected Zone ◽  
Corrosion Current Density ◽  
Filler Metal ◽  
Corrosion Current ◽  
Piston Crown

Since the oil price has been significantly jumped for recent some years, the diesel engine of the merchant ship has been mainly used the heavy oil of low quality. Thus, it has been often exposed to severely corrosive environment more and more because temperature of the exhaust gas of a combustion chamber is getting higher and higher with increasing of using the heavy oil of low quality. As a result, wear and corrosion of the most parts surrounded with combustion chamber is more serious compared to the other parts of the engine. Therefore, an optimum repair welding for these parts is very important to prolong their lifetime in a economical point of view. In this study, 0.5Mo filler metal was welded with SMAW method in the forged steel which would be generally used with piston crown material. And the corrosion properties of weld metal zone, heat affected zone and base metal zone were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% H2SO4 solution. The heat affected and base metal zones exhibited the highest and lowest values of hardness respectively. And, the corrosion current density of the heat affected zone indicated the lowest value, having the highest value of hardness. It appeared that the corrosive products with red color was wholly covered on the surface of the base metal zone, while its products was not observed in the heat affected zone. The microstructure of the pearlite with black color was more or less observed in the base metal zone with patterns such as crystal and needle, in particular, the crystal pattern of ferrite microstructure with white color was considerably included in the base metal and heat affected zone, and the ferrite microstructure was significantly observed in the weld metal zone. In particular, the polarization characteristics such as impedance, polarization curve associated with corrosion resistance property were well in good agreement with each other. Keywords: Forged steel, Microstructure, 0.5Mo filler metal, SMAW, Weld metal zone, Electrochemical method, Corrosion current density, Hardness.

Comparison of Behaviour of Different Variants of Hydrogenated TRIP Steels at Slow Strain Rate Tests

2019 ◽  
Vol 810 ◽  
pp. 70-75
Author(s):  
Petra Váňová ◽  
Jaroslav Sojka ◽  
Kateřina Konečná ◽  
Taťána Radkovská
Keyword(s):  
Hydrogen Embrittlement ◽  
Hydrogen Absorption ◽  
Potassium Thiocyanate ◽  
Tensile Tests ◽  
Fracture Characteristics ◽  
Trip Steels ◽  
Hydrogen Charging ◽  
Metallic Inclusions ◽  
Significant Difference ◽  
Fracture Micromechanism

The paper describes effect of hydrogen on mechanical properties and fracture characteristics of two types of C-Mn-Si TRIP steel; laboratory prepared steel TRIP 800 and commercially manufactured steel TRIP 780. TRIP steels are very promising materials thanks to their combination of a very good strength and toughness. However, these steels can be embrittled by hydrogen during technological operations related to galvanizing. That is why the knowledge of effects of hydrogen on the properties and fracture characteristics of the TRIP steels is of particular importance. In the presented study, effects of hydrogen were studied by tensile tests after electrolytical hydrogen charging. Electrolytical hydrogen charging was performed in 0.05 M solution of sulfuric acid with addition of potassium thiocyanate to promote hydrogen absorption. Hydrogen provoked embrittlement in both steel variants and changed their fracture micromechanism. Hydrogen embrittlement manifested itself mainly by a loss of plasticity. Index of hydrogen embrittlement, expressed on the basic of a relative drop of elongation to fracture, reached values about 77 % for the steel variant TRIP 800, resp. 83 % for the steel variant TRIP 780. No significant difference was observed between two steel variants studied. Concerning fractographic characteristics, steels containing hydrogen displayed quasi-cleavage fracture mostly on the edges of the sample and around elongated non-metallic inclusions.

scholarly journals Generic failure mechanisms in adhesive bonds

Holzforschung ◽  
2013 ◽  
Vol 67 (2) ◽  
pp. 207-215 ◽  
Author(s):  
Philipp Hass ◽  
Falk K. Wittel ◽  
Peter Niemz
Keyword(s):  
Crack Propagation ◽  
Urea Formaldehyde ◽  
Failure Mechanisms ◽  
Tensile Tests ◽  
Propagation Path ◽  
Adhesive Properties ◽  
Adhesive Bonds ◽  
Stable Crack Propagation ◽  
Order Of Magnitude

Abstract The failure of adhesive bondlines has been studied at the microscopic level via tensile tests. Stable crack propagation could be generated by means of samples with improved geometry, which made in situ observations possible. The interaction of cracks with adhesive bondlines under various angles to the crack propagation was the focus of this study, as well as the respective loading situations for the adhesives urea formaldehyde (UF), polyurethane (PUR), and polyvinyl acetate (PVAc), which have distinctly different mechanical behaviors. It has been shown how adhesive properties influence the occurrence of certain failure mechanisms and determine their appearance and order of magnitude. With the observed failure mechanisms, it becomes possible to predict the propagation path of a crack through the specimen.

scholarly journals In situ small-scale hydrogen embrittlement testing made easy: An electrolyte for preserving surface integrity at nano-scale during hydrogen charging

2018 ◽  
Vol 43 (27) ◽  
pp. 12516-12529 ◽  
Author(s):  
Tarlan Hajilou ◽  
Malin S.B. Hope ◽  
Amin H. Zavieh ◽  
Nousha Kheradmand ◽  
Roy Johnsen ◽  
...  
Keyword(s):  
Hydrogen Embrittlement ◽  
Surface Integrity ◽  
Small Scale ◽  
Hydrogen Charging ◽  
Nano Scale

Susceptibility Study to Hydrogen Embrittlement of Welded Joints of API 5L X52 Steel in Sulphide Media

2020 ◽  
Vol 1158 ◽  
pp. 27-42
Author(s):  
Daniel Kohls ◽  
Enori Gemelli ◽  
Laercio da Silva Filho ◽  
Majorie Anacleto Bernardo
Keyword(s):  
Hydrogen Embrittlement ◽  
Base Metal ◽  
Welded Joints ◽  
Oil And Gas ◽  
Welded Joint ◽  
Welding Process ◽  
High Strength ◽  
Tensile Tests ◽  
Low Alloy Steels ◽  
X52 Steel

Pipelines for oil and gas, manufactured in high-strength low-alloy steels (HSLA), such API pipes, promote high levels of strength and fracture toughness. Therefore, it is important to ensure this high level of toughness in the welded joint. When the pipelines are exposed for many years to wet H2S environments, they can fail due to hydrogen embrittlement. Thus, it is important to evaluate the influence of different weld specifications in the susceptibility to hydrogen embrittlement. In this case, the aim of this work was to study the susceptibility to hydrogen embrittlement of API 5L X52 steel and in the welded region in wet environments. The welding was performed in the circumferential direction by GMAW process in two different specifications (with lower and higher thermal input). The susceptibility to hydrogen embrittlement was carried out according to NACE TM0177 and SSRT (slow strain rate tensile tests) test, performed according to ASTM G 129 standard. All welded joints and base metal did not show any signal of cracks and susceptibility to hydrogen embrittlement, according to the requirements of the NACE TM0177 test. According to SSRT tensile test, the results showed that the welded joints and base metal are susceptible to hydrogen embrittlement. The tensile tests exhibited a drop in the strain and necking, and higher values of yield stress. The welded joint with the lowest heat inputs employed in the welding process presented the highest susceptibility to hydrogen embrittlement.

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