Investigation of idiomorphic ferrite and allotriomorphic ferrite using electron backscatter diffraction technique

Abstract

A heat treatment for a vanadium-containing steel involving high-temperature austenitisation followed by two-stage isothermal holding was deliberately conducted to produce allotriomorphic ferrite (ALF), idiomorphic ferrite (IDF) and martensite. The resulting microstructures and crystallographic relationships with respect to the parent austenite grains were examined using the electron backscatter diffraction technique. Results indicated that IDF grains did not possess a specific orientation relationship (OR) with respect to the surrounding austenite matrix. The detailed substructures of IDF were also examined. In contrast, the ALF grains had an approximate Kurdjumov–Sachs OR with respect to one or both of the adjacent austenite grains; the latter case was termed a dual OR and was analysed in detail.

Keywords:

• Vanadium-containing steel
• Idiomorphic ferrite
• Allotriomorphic ferrite
• Electron backscatter diffraction
• Pole figure
• Orientation relationship
• Coordinate matrix

Acknowledgements

This work was carried out with the financial support from Ministry of Science and Technology, Taiwan, under the Contract No. NSC 102-2221-E-002-058-MY3. The authors are grateful to Tung Ho Steel Enterprise Corporation, Taiwan, for providing the experimental steel bars.

ORCiD

Y. T. Tsai http://orcid.org/0000-0003-4897-5459

J. R. Yang http://orcid.org/0000-0001-7897-7039