Improved hydrogen embrittlement resistance after quenching–tempering treatment for a Cr-Mo-V high strength steel

Hao

et al. 2022

J. Phys.: Conf. Ser.

Hydrogen-induced delayed cracking is an important factor leading to the failure of ultra-high strength steels during service, thus in this study, the mechanical properties and hydrogen trapping of hot formed 22MnB5 steel considering different content of V (0, 0.05, 0.09 wt.%) and corresponding microstructure were investigated. Slow strain rate tensile tests (SSRT) were applied to obtain the tensile strength and elongation of samples under different medium conditions (air, HCl immersion and electrolytic hydrogen charging). Besides, microstructure and atomic distribution morphology of the samples were detected and analyzed by transmission electron microscope (TEM) and atomic probe tomography (APT) technique. Results showed that both resistances of hydrogen-induced delayed cracking in MnB-V5 and MnB-V9 samples were obviously better than that in MnB-V0 sample, besides, the delayed cracking resistances of MnB-V9 and MnB-V5 samples did not improve with the increase of V content, but basically remained the same. Lamellar residual austenite was found in all samples, but no hydrogen was grasped in the same area according to APT result. There was intragranular cementite in all samples, and it has grasped H in the same position. The carbides formed by V, Ti and other alloying elements were found in MnB-V5 and MnB-V9 and were considered to be an important factor in improving the anti-hydrogen delayed cracking performance of the steel.

Section: Resultsmentioning

confidence: 99%

Microstructure characteristic of hot formed 22MnB5 steel and its relationship with delayed hydride cracking property

Hao

et al. 2022

J. Phys.: Conf. Ser.

Materials Science and Technology

“…Post-heat treatment usually requires heating the specimens to 200-300 °C and holding for 1-2 h, which can achieve a better dehydrogenation effect [18,19]. Wang et al [23] pointed out that dehydrogenation by post-heat treatment had no significant influence on the microstructures and mechanical properties. There are few studies on the effect of dehydrogenation by post-heat treatment on microstructures and mechanical properties, and the mechanism of post-heat treatment affecting them has not reached a unified consensus.…”

Section: Introductionmentioning

confidence: 99%

Effect of post-heat treatment on microstructure and properties of EH47 steel CGHAZ

Yang

et al. 2023

To clarify the effect of post-heat treatment on the microstructure and mechanical properties of the coarse-grained heat-affected zone (CGHAZ) for EH47 steel, simulated CGHAZ specimens were subjected to post-heat treatment at 250°C for 1.0 h. The results showed that the microstructure of CGHAZ was composed of granular bainite (GB) and lath bainite (LB), and a large number of iron-carbon particles (∼81 nm) were precipitated after post-heat treatment. The relationship between dislocations, low-angle grain boundaries and iron-carbon particles was revealed by KAM values. The iron-carbon particles hindered the movement of sub-grain boundaries and dislocations, thereby increased the yield strength (∼120 MPa). The precipitation of iron-carbon particles caused the cracking of bainite ferrite and reducing the fracture toughness of CGHAZ.

“…Their results demonstrated that there is an extra-peak below 200 °C , which was attributed to the hydrogen trapping of vanadium carbide. Wang et al [22] studied effect of quenching-tempering treatment on the hydrogen embrittlement resistance of a reactor pressure vessel steel and found that two hydrogen states were identified in the hydrogen desorption profiles and the high temperature peak is the irreversible hydrogen. Although the TDS method has been used to study the mechanism of hydrogen embrittlement, due to the dissimilarities in the microstructure and chemical compositions of various materials, hydrogen absorption properties, including the hydrogen solubility and hydrogen permeability of each steel, are not the same [23,24].…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation on the hydrogen embrittlement characteristics and mechanism of natural gas-hydrogen transportation pipeline steels

Cai

Bai

Gao

et al. 2022

Mater. Res. Express

Self Cite

Hydrogen blended with natural gas is one of the best ways for large-scale hydrogen transportation; however, pipeline steels exploited for transferring natural gas have the risk of hydrogen embrittlement. Therefore, the hydrogen damage mechanism and resistance property of different steel pipelines should be carefully examined to select suitable materials for the task mentioned above. The common X42, X52, X70, and AISI 1020 are taken into account as research objects. Their mechanical properties and hydrogen absorption properties in a hydrogen environment are investigated to explore further factors affecting the hydrogen embrittlement of material. Dynamic slow strain rate tensile test results show that these materials exhibit varying hydrogen embrittlement sensitivity in a hydrogen environment. AISI 1020 has the highest hydrogen embrittlement susceptibility, then X70, and X42 presents the lowest one. Generally, hydrogen embrittlement behaviours are strengthened by increasing the current density. As the current density grows, the fracture mode of pipeline steels transforms from the ductile fracture to the quasi-cleavage fracture and finally turns into the cleavage fracture. The hydrogen embrittlement fracture of the tensile specimen results from the action of the HEDE and HELP in various zones. TDS test results indicates that the content of C and Mn significantly influence on the hydrogen solubility in metal materials.