AUTHOR=Wang Zhen , Liu Jing , Huang Feng , Bi Yun-jie , Zhang Shi-qi 

TITLE=Hydrogen Diffusion and Its Effect on Hydrogen Embrittlement in DP Steels With Different Martensite Content

JOURNAL=Frontiers in Materials

VOLUME=7

YEAR=2020

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2020.620000

DOI=10.3389/fmats.2020.620000

ISSN=2296-8016

ABSTRACT=<p>The hydrogen diffusion behavior and hydrogen embrittlement susceptibility of dual phase (DP) steels with different martensite content were investigated using the slow strain-rate tensile test and hydrogen permeation measurement. Results showed that a logarithmic relationship was established between the hydrogen embrittlement index (<italic>I</italic><sub>HE</sub>) and the effective hydrogen diffusion coefficient (<italic>D</italic><sub>eff</sub>). When the martensite content is low, ferrite/martensite interface behaves as the main trap that captures the hydrogen atoms. Also, when the <italic>D</italic><sub>eff</sub> decreases, <italic>I</italic><sub>HE</sub> increases with increasing martensite content. However, when the martensite content reaches approximately 68.3%, the martensite grains start to form a continuous network, <italic>D</italic><sub>eff</sub> reaches a plateau and <italic>I</italic><sub>HE</sub> continues to increase. This is mainly related to the reduction of carbon content in martensite and the length of ferrite/martensite interface, which promotes the diffusion of hydrogen atoms in martensite and the aggregation of hydrogen atoms at the ferrite/martensite interface. Finally, a model describing the mechanism of microstructure-driven hydrogen diffusion with different martensite distribution was established.</p>