Modification of grain boundary microstructure by controlling dissolution behavior of θ particles in Cr-containing hypereutectoid steel

Yamamoto, Koji; Takayama, Takemori; Minamino, Yoritoshi; Tokunaga, Toko; Hagihara, Koji

doi:10.1016/j.matchar.2023.113241

Cited by 4 publications

(1 citation statement)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In SUJ2 at around 780 ℃, the substitutional atoms such as Cr atoms diffuse slowly inside grains by the lattice diffusion mechanism with high activation energy 20) . On the other hand, the substitutional atoms diffuse extremely rapidly along grain boundaries by the grain boundary diffusion mechanism with low activation energy.…”

Section: Gba Treatmentmentioning

confidence: 99%

Effect of Rolling and Alloying Elements on the Impact Properties of Hypereutectoid Steels

Tokunaga,

Minamino,

Yamamoto

et al. 2024

ISIJ Int.

Self Cite

View full text Add to dashboard Cite

In this study, to develop steel with high strength and ductility, steels are designed based on JIS-SUJ2 hypereutectoid steel by controlling the contents of the alloying elements Cr and Mn. The steels are subjected to two types of specially designed heat treatment, i.e., "grain boundary amelioration (GBA)" treatment, with and without rolling. The effects of the alloy type and rolling on the microstructure and impact properties are investigated. High impact values over 50 J/cm 2 were achieved compared to those of conventional steels by the significant refinement of γ grains with GBA treatment. All the steels exhibit transgranular fracture, and no intergranular fracture was observed. This indicates that the proposed heat treatment achieved the suppression of intergranular fracture by inhibiting the formation of θ particles on the grain boundaries and by refining the prior γ grains. Moreover, it has been suggested that the impact values were strongly affected by the C content in the matrix which is controlled by the alloying element and by the heat treatment. As the C content increases, hardness and fraction of the retained γ phase increase, which leads to the decrease in impact value. In samples where prior γ grains were extremely fine and θ particles were fine, area fraction and circularity of the θ particles did not have a significant effect on the impact values.

show abstract

Section: Gba Treatmentmentioning

confidence: 99%