Effect of Specimen Geometry on the Thermal Desorption Spectroscopy Evaluated by Two-Dimensional Diffusion-Trapping...

Area of Science:

• Materials Science
• Metallurgical Engineering
• Physical Chemistry

Background:

• Hydrogen embrittlement is a critical concern in ferritic steels.
• Accurate characterization of hydrogen diffusion and trapping is essential for material integrity.
• Thermal Desorption Spectroscopy (TDS) is a key technique for studying hydrogen behavior.

Purpose of the Study:

• To investigate the influence of specimen geometry on hydrogen diffusion simulations in ferritic steel.
• To analyze the impact of specimen size on Thermal Desorption Spectroscopy (TDS) data.
• To improve the interpretation of TDS results by accounting for geometric effects.

Main Methods:

• Finite element method (FEM) simulation of hydrogen diffusion and trapping.
• Development and verification of a two-dimensional diffusion-trapping coupled model.
• Systematic variation of cylindrical specimen height to assess geometric effects.

Main Results:

• Hydrogen concentration measurements are unaffected by geometry in ideal simulations due to mass conservation.
• Hydrogen escape during experimental procedures (transfer, evacuation) makes measured TDS curves highly geometry-dependent.
• Smaller specimen sizes lead to reduced peak flux and increased errors in determining trap deactivation energy using the Kissinger method.

Conclusions:

• Specimen geometry is a critical factor influencing the reliability of TDS analysis for hydrogen in ferritic steel.
• The 'size effect' must be considered for accurate interpretation of TDS data, particularly for smaller samples.
• This study provides insights for optimizing experimental design and data analysis in hydrogen embrittlement research.