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Multilayered steel

Performance of DP590

DP steel is widely applied to the components in automobile to absorb energy during accident. The exceptional deformability of DP steel is the key to the passenger's safety.

Performance of multilayered steel

By replacing DP590 with multilayered steel, even better energy absorption is expected. The experiment was conducted with the exactly the same condition as DP590, such as sheet thickness, column width and length, and applied impact energy.

Phase transformation of low-carbon steels observed by laser microscope

Formation of ferrite side plates

Ferrite side plate is one of the microstructures of low-carbon steel develops during continuous cooling process. Understanding of the formation kinetics is important for controlling performance of low-carbon steels, especially in heat affected zone of weld joint. In-situ observation has been conducted to clarify the formation mechanism.

  1. 奥信明, 朝倉健太郎, 井上純哉, 小関敏彦. "低炭素鋼の連続冷却過程におけるフェライトプレート形成その場観察." 鉄と鋼, 94 (2008) 363-368.

Formation of martensite blocks

Martensite in low-carbon steel has a unique characteristics with respect to the crystal orientation relationship, which affects the mechanical properties of low-carbon steels, such as strength and toughness. Thus, numerous investigations have been conducted to clarify the crystallographic features of the martensite microstructure. In-situ observation has been conducted to clarify the formation mechanism.

  1. S. Nambu, N. Shibuta, M. Ojima, J. Inoue, T. Koseki, and H. K. D. H. Bhadeshia. "In situ observations and crystallographic analysis of martensitic transformation in steel." Acta materialia, 61 (2013) 4831-4839.

Surface relief effects induced by phase transformation of low-carbon steels measured by DHM

Formatin of ferrite side plate

Bra bra bra ...

  1. S. Komine, K. Sekido, and J. Inoue. "In-situ measurement of surface relief induced by Widmanstätten and bainitic ferrites in low carbon steel by digital holographic microscopy." Scripta Materialia, 162 (2019) 241-245.

Formatin of ferrite side plate

Bra bra bra ...

  1. S. Komine, K. Sekido, and J. Inoue. "In-situ measurement of surface relief induced by Widmanstätten and bainitic ferrites in low carbon steel by digital holographic microscopy." Scripta Materialia, 162 (2019) 241-245.

Dislocation movement and boundary sliding during plastic deformation of low-carbon steels observed by ECCI

Dislocation movement 

Dislocations were observed to move under relatively low stress levels. Two distinct types of features were observed after loading to 387 MPa. One is a noticeable alteration in the dislocation line shape, the other is the sharp linear patterns. The observed line patterns align with the trace of the slip plane, suggesting that these line patterns are slip lines on the surface created by dislocation motion.

  1. S. Gong, M. Zhang, J. Inoue, "In-situ electron channeling contrast imaging of local deformation behavior of lath martensite in low-carbon-steel", Acta Materialia, 280 (2024) 120337 https://doi.org/10.1016/j.actamat.2024.120337

Block boundary sliding

Significant boundary sliding was observed on the block boundary, which is considered responsible for the primary plastic deformation. 

  1. S. Gong, M. Zhang, J. Inoue, "In-situ electron channeling contrast imaging of local deformation behavior of lath martensite in low-carbon-steel", Acta Materialia, 280 (2024) 120337 https://doi.org/10.1016/j.actamat.2024.120337

Slip band formation during plastic deformation of low-carbon steels observed by DHM

In preparation...