Top Result for FY2022
Multiscale 3D analysis of the intergranular fracture mechanism in high-strength steel
Akinobu Shibata
Distinguished Group Leader, Steel Research Group, Materials Evaluation Field, Research Center for Structural Materials
Multiscale 3D analysis has revealed that brittle intergranular cracks propagate discontinuously, and a low-angle boundary segment can act as a strong obstacle to crack propagation in high-strength martensitic steel.
A novel technique for analyzing fracture phenomena, multiscale 3D analysis using X-ray CT and FIB-SEM serial sectioning (3D EBSD), has been established.
Based on the results of this research, we proposed a material design concept for the development of high-strength steels with high resistance to brittle fracture.
Q＆A
Q：Why do you conduct research on steel materials?
A：Steel research may sound old-fashioned, but we are surrounded by various steels in our daily lives, such as in automobiles and tools. We are conducting steel research because the development of innovative and novel steels can make our lives more comfortable, including through the creation of safe and secure infrastructures.
Q：How does this research lead to real-life improvements?
A：Developing materials twice as strong as those currently used could cut materials usage in half. Consequently, there is strong demand for the development of high-strength steels for energy-conservation measures and to realize a decarbonized society. Nonetheless, increasing the strength of steels results in issues of brittle fracture. This research has elucidated the mechanism of brittle intergranular fracture in high-strength steels, aiming to suppress brittle fractures. This work is expected to pave the way for developing high-strength steels resistant to brittle fracture, enabling the creation of automobiles and earthquake-resistant buildings that remain intact even after collisions.
Q：What are the key points of this achievement?
A：Since the fracture of materials is complicated, we considered it necessary to investigate the fracture process in three dimensions in order to clarify the mechanism. In this research, we have elucidated the fracture mechanism of high-strength steels using a novel research method, a three-dimensional analysis of fracture behavior on multiple scales ranging from nanometer (10-9m) to millimeter (10-3m).
Q：How does your personality seem to match with your research?
A：I like to think things through thoroughly and deeply, and I am a person who never gives up until I am satisfied with my work. In this research, I have been able to clarify the fracture mechanism of high-strength steel materials as a result of my thorough day-and-night thinking about the vast amount of data obtained by state-of-the-art technology, and also as a result of the great support of my co-authors.