Crystallographic characterization of steel microstructure using neutron diffraction

Area of Science:

• Materials Science
• Metallurgy
• Analytical Chemistry

Background:

• Steel microstructure evaluation is critical for advanced material applications.
• Traditional methods like EBSD and X-ray diffraction have limitations in accurately measuring austenite volume fraction and texture simultaneously.
• Neutron diffraction presents a promising alternative for comprehensive microstructure analysis.

Purpose of the Study:

• To summarize applications of neutron diffraction for steel microstructure evaluation.
• To compare neutron diffraction with other techniques for measuring austenite (γ) volume fraction and texture.
• To investigate phase transformations and their effects on steel properties using neutron diffraction.

Main Methods:

• Neutron diffraction for simultaneous measurement of volume fraction and texture.
• In situ monitoring of austenite reverse transformation using dilatometry, EBSD, X-ray diffraction, and neutron diffraction.
• Convolutional multiple whole profile fitting for dislocation density determination.

Main Results:

• Neutron diffraction recommended for simultaneous austenite volume fraction and texture measurement.
• Excellent agreement in γ reversion kinetics between dilatometry and neutron diffraction.
• Discrepancies observed with EBSD and X-ray diffraction attributed to surface chemical changes.
• Phase transformations upon cooling elucidated changes in ferrite (α) and γ lattice parameters.
• Martensitic transformation monitored, revealing insights into internal stresses and martensite axial ratio.

Conclusions:

• Neutron diffraction is a powerful tool for accurate steel microstructure evaluation.
• It provides reliable data on phase transformations and material properties.
• This technique offers new insights into internal stresses and lattice parameter changes in steels.