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Materials 2018, 11(5), 788; https://doi.org/10.3390/ma11050788

Effect of Cementite on the Hydrogen Diffusion/Trap Characteristics of 2.25Cr-1Mo-0.25V Steel with and without Annealing

1
School of Chemical Engineering and Technology, Xi’an Jiaotong University, Xi’an 710049, China
2
School of Aerospace, Xi’an Jiaotong University, Xi’an 710049, China
*
Authors to whom correspondence should be addressed.
Received: 26 March 2018 / Revised: 26 April 2018 / Accepted: 2 May 2018 / Published: 12 May 2018
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Abstract

Hydrogen embrittlement (HE) is a critical issue that affects the reliability of hydrogenation reactors. The hydrogen diffusivity/trap characteristics of 2.25Cr-1Mo-0.25V steel are important parameters mainly used to study the HE mechanism of steel alloys. In this work, the hydrogen diffusivity/trap characteristics of heat-treated (annealed) and untreated 2.25Cr-1Mo-0.25V steel were studied using an electrochemical permeation method. The microstructures of both 2.25Cr-1Mo-0.25V steels were investigated by metallurgical microscopy. The effect of cementite on the hydrogen diffusivity/trap mechanisms was studied using thermodynamics-based and Lennard–Jones potential theories. The results revealed that the cementite located at the grain boundaries and at the interfaces of lath ferrite served as a kind of hydrogen trap (i.e., an irreversible hydrogen trap). In addition, hydrogen was transported from ferrite to cementite via up-hill diffusion, thereby supporting the hypothesis of cementite acting as a hydrogen trap. View Full-Text
Keywords: hydrogen embrittlement; 2.25Cr-1Mo-0.25V; hydrogen diffusion; hydrogen trap; electrochemical permeation method hydrogen embrittlement; 2.25Cr-1Mo-0.25V; hydrogen diffusion; hydrogen trap; electrochemical permeation method
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Song, Y.; Han, Z.; Chai, M.; Yang, B.; Liu, Y.; Cheng, G.; Li, Y.; Ai, S. Effect of Cementite on the Hydrogen Diffusion/Trap Characteristics of 2.25Cr-1Mo-0.25V Steel with and without Annealing. Materials 2018, 11, 788.

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